20131211-2013.12Reports

Annex A to UK AIRPROX BOARD: MONTHLY REPORT – DECEMBER 2013 

Table 1 

Assessment Summary Sheet for UKAB Meeting on 11 th December 2013 

Total Risk A Risk B Risk C Risk D Risk E 

15 2 3 4 2 4 

Airprox 

Reporting 

(Type) 

Reported 

(Type) 

Airspace 

(Class) 

Cause 

ICAO 

Risk 

ERC 

Score 

2013075 Sea King 

(RN) 

Pegasus 

Quantum 

(Civ Pte) 

LFA 3 

Culdrose AIAA 

(G) 

A late sighting by the Sea 

King pilot. 

B. 101. 

2013082 A319 

(CAT) 

Paramotor 

(Unknown) 

Lon FIR 

(G) 

Effectively, a non-sighting 

by the A319 pilot. 

Recommendation: The CAA 

reviews the regulation and 

licensing of para-motor 

glider pilots. 

A. 2500. 

2013083 Vigilant 

(HQ Air Trg) 

PA28 

(Civ Club) 

Lon FIR 

(G) 

The PA28 pilot flew close 

enough to the Vigilant to 

cause its pilot concern. 

C. 20. 

2013084 Vigilant 

(HQ Air Trg) 

Hurricane 

(Unknown) 

Lon FIR 

(G) 

The Hurricane pilot flew 

close enough to the Vigilant 

to cause its pilot concern. 

C. 4. 

2013085 A320 

(CAT) 

DH8D 

(CAT) 

Daventry CTA 

(A/C) 

The Welin controller allowed 

the DH8D to come into 

conflict with the A320. 

C. 50. 

2013088 LS8 Glider 

(Civ Pte) 

Light Aircraft 

(Unknown) 

Lon FIR 

(G) 

Confliction in Class G. D. N/S. 

2013089 PA18 

(Civ Trg) 

R44 Helicopter 

(Civ Trg) 

Wellesbourne ATZ 

(G) 

The R44 crew flew into 

conflict with the PA18, 

which they did not see. 

Contributory: The 

Wellesbourne Mountford 

Aerodrome, FISO manuals 

and AIP entry did not 

include information wrt 

grass runway operations. 

Recommendation: 

Wellesbourne Mountford 

review their AIP entry wrt 


A. 20. 

2013091 A330 

(CAT) 

Unknown 

Lon CTA 

(C) 

Sighting report. D. N/S. 

2013092 EV-97 

(Civ Trg) 

Mooney M20J 

(Civ Pte) 

Lon FIR 

(G) 

The M20 pilot flew close 

enough to the EV97 to 

cause its pilot concern. 

B. 20. 

2013095 RJ1H 

(CAT) 

Robin DR400 

(Civ Pte) 

London/City CTA 

(D/G) 

TCAS sighting report. 


reviews VFR/SVFR traffic 

procedures within CAS wrt 

RA occurrences in TCAS 

equipped aircraft. 

E. 1.

Airprox 

Reporting 

(Type) 

Reported 

(Type) 

Airspace 

(Class) 

Cause 

ICAO 

Risk 

ERC 

Score 

2013097 ASH 26 

(Civ Pte) 

C182 

(Civ Pte) 

Lon FIR 

(G) 

A late sighting by both 

pilots. 

B. 4. 

2013099 RJ1H 

(CAT) 

R44 

(Civ Pte) 

London City CTR 

(D) 







E. 1. 

2013101 Tucano T1 

(HQ Air Trg) 

Glider 

(Unknown) 

Vale of York AIAA 

(G) 

A conflict in Class G 

airspace. 

C. 4. 

2013103 Tornado GR4 

(HQ Air Ops) 

AS350 

(Civ Comm) 

Scotland FIR 

(G) 

Sighting report. E. 1. 

2013121 RJ1H 

(CAT) 

A109 

(Civ Exec) 

London City CTR 

(D) 







E. 1.

AIRPROX REPORT No 2013075 

Date/Time: 26 Jun 2013 1122Z 

Position: 

5015N 00519W 

(1.5nm North of Camborne) 

Airspace: LFA 3 (Class: G) 

Culdrose AIAA 

Reporting Ac 

Reported Ac 

Type: Sea King Pegasus 

Quantum 

Operator: RN Civ Pte 

Alt/FL: 1200ft 1500ft 

RPS (1029hPa) QNH (NK) 

Weather: VMC HAZE VMC 

Visibility: 15km NK 

Reported Separation: 

50ft V/50m H 

Recorded Separation: 

NK 

0ft V/400ft H 

Diagram based on pilot reports 

and GPS log 

CPA 1122 

Culdrose MATZ 

1120 

Perranporth ATZ 

1118 

Quantum 

Camborne 

Sea King 

PART A: SUMMARY OF INFORMATION REPORTED TO UKAB 

THE SEA KING PILOT reports conducting a post-maintenance flight test, seated in the RH seat with 

an Observer in the LH seat. The grey camouflaged aircraft had navigation lights and HISL selected 

on, as was the SSR transponder with Modes A and C. The aircraft was not fitted with an ACAS. The 

handling pilot was operating under VFR in VMC, in receipt of a Basic Service from Culdrose APR. 

Whilst flying a NE-SW race track pattern, in a right hand turn at 90kt with 15° angle of bank, the 

handling pilot saw a high-wing microlight through the left chin window at a range of 100m. It appeared 

to be climbing and was converging from below. He called the confliction to the crew and increased 

bank angle to about 35° to avoid the microlight. He noted that, prior to entering the turn, the observer 

had been 'eyes in', conducting part of the flight test procedure. The microlight passed astern at a 

range of about 50m and slightly below; it was not observed to manoeuvre at any point. The pilot 

stated that it was believed the microlight was ‘underneath the nose’ of the Sea King at the point of 

commencing the right turn and was therefore obscured by the instrument panel. The microlight only 

became visible as it climbed towards the left chin window. Equipment on board the Sea King was set 

to interrogate ‘IFF Modes 3/A and C’; no returns were observed within 5nm of the helicopter for the 

duration of the flight. 

He assessed the risk of collision as ‘Medium’. 

THE QUANTUM PILOT reports conducting a pleasure flight. The yellow and blue aircraft was not 

fitted with lighting, an SSR transponder or an ACAS. The pilot was operating under VFR in VMC with 

a Basic Service from Newquay APR. In straight-and-level cruise at 50kt, heading 225°, at 1500ft on 

the QNH, he and his passenger saw a grey Sea King helicopter in the left 10.30 position at a range of 

3km. The Sea King appeared to be on a heading of about 315°, at the same altitude, before it then 

turned 90° right and flew past them, going in the opposite direction, at a distance of approximately 

2km. Just after passing them, the helicopter turned 90° to the right again to assume a heading of 

135°, before turning 90° right again to fly parallel with them. Due to the higher speed of the helicopter, 

it overtook them. It then turned right 90° back to its original heading of about 315°. At this point, 

because the helicopter was now on a constant relative bearing, the Quantum pilot grew anxious that 

the Sea King pilot was not aware of their location. At around 400ft away to his left, the helicopter 

turned sharply right to avoid them, at which point the Quantum pilot descended to avoid any possible 

1

otor wash. Shorty afterwards, Newquay APR requested that he switch frequency to his destination. 

The Quantum pilot stated that, having checked NOTAMS before the flight, it appeared that Culdrose 

was not ‘offering a service’ that day. Therefore, he felt Newquay was his only option for a Basic 

Service. On his return to home base that day, he spoke to a flying instructor, who checked the 

NOTAMS and confirmed that Culdrose were not ‘offering a service’. 


CULDROSE ATC reports that on the day of the Airprox, the Culdrose ATC radar was operating SSR 

only. Culdrose APR was only aware that the Airprox had taken place when the Sea King pilot 

reported it on frequency at 1123. The Culdrose SUP was informed and, because the microlight pilot 

was not on frequency, and was non-squawking (and therefore not on the radar display), immediate 

action was taken to identify who was working the microlight. Newquay International reported that they 

had just sent a microlight en route to Lands End but could not see his primary return. Lands End 

reported that they had a microlight from Perranporth, inbound to them. Lands End rang back to state 

that they had spoken to the pilot of the microlight who reported that a Sea King had orbited and 

passed him twice, but that no traffic information had been passed by Newquay ATC. 

NEWQUAY ATC report that the Quantum pilot was in receipt of a Basic Service. The Quantum pilot 

did not declare an Airprox whilst on frequency and the controller did not recall any event of note. 

Analysis of the radar recording established that the microlight did not paint on radar at any time whilst 

in receipt of the ATS. 

Factual Background 

The weather at RNAS Culdrose was recorded as follows: 

METAR EGDR 261127Z 25005KT 9999 FEW012 FEW020TCU SCT024 BKN220 16/13 Q1032 WHT TEMPO 

SCT012 GRN 

Analysis and Investigation 

UKAB Secretariat 

Both pilots were operating under VFR in Class G airspace and had equal responsibility for 

collision avoidance 1 ; the Sea King pilot was required to give way 2 . Both pilots were in receipt of a 

Basic Service, defined as follows 3 : 

‘A Basic Service is an ATS provided for the purpose of giving advice and information useful for the 

safe and efficient conduct of flights. This may include weather information, changes of 

serviceability of facilities, conditions at aerodromes, general airspace activity information, and any 

other information likely to affect safety. The avoidance of other traffic is solely the pilot’s 

responsibility. 

Basic Service relies on the pilot avoiding other traffic, unaided by controllers/FISOs. It is 

essential that a pilot receiving this service remains alert to the fact that, unlike a Traffic Service 

and a Deconfliction Service, the provider of a Basic Service is not required to monitor the 

flight.’ 

It was established that neither Eurocontrol nor the RAF Low Flying Operations Squadron had 

issued a NOTAM for RNAS Culdrose for the date of the incident. There was no record of the 

reported NOTAM and therefore any content could not be established. It was ascertained in 

subsequent conversation with RNAS Culdrose that the station often rang round ‘local airfields’ on 

a daily basis to pass on operating information that was deemed important to other airspace users. 

1 Rules of the Air 2007 (as amended), Rule 8 (Avoiding aerial collisions). 

2 ibid., Rule 9 (Converging). 

3 CAP774 (UK Flight Information Services), Chapter 2 (Basic Service), paragraph 1 (Definition). 

2

Although the microlight aircraft’s registration and home airfield was identified by Culdrose ATC on 

the day of the Airprox, this information was not conveyed to the Airprox Board until 23 rd October, 

some 4 months after the event. The microlight pilot provided a full report but his recollection of 

events was not assisted by the avoidable delay in notifying him. The RNAS Culdrose Occurrence 

Investigation did not retain a copy of the reported NOTAM. The Airprox occurred within the 

boundary of a notified hang/para-gliding winch-launch site with a maximum cable altitude of 

2300ft. The CAA 1:500,000 4 and 1:250,000 5 charts recommend that ‘aircraft should avoid 

overflying these sites below the indicated altitude’. The Military 1:500,000 low-flying chart displays 

symbology denoting winch-launched hang-gliding in the same area but without a promulgated 

maximum cable altitude. The UK Military Low Flying Handbook entry for LFA3 does not 

promulgate hang/para-gliding activity in that area. 

RN Occurrence Investigation 

The RN Occurrence Investigation concluded that the Sea King pilot was operating in VMC under 

a Basic Service and came into conflict with a microlight, the pilot of which elected not to obtain a 

TS from Culdrose [UKAB Note 1: in fact Culdrose could not have offered a TS given that it was 

SSR-only and the Quantum had no SSR]. While it is understood he was visual with [Sea King 

C/S], had he called Culdrose, then this might have delivered greater SA to all, and resulted in 

cued and more effective lookout from the [Sea King C/S] crew. Such a call might also have been 

advisable given that Culdrose was operating SSR only (which had been promulgated by NOTAM) 

and therefore would not have been aware of the microlight’s presence by radar. [UKAB Note 2: 

the relevant authority had no record of a NOTAM being issued]. 

Comments 

Navy HQ 

The Sea King was operating VMC under a BS and came into conflict with a microlight that had 

elected not to call Culdrose during its transit. Whilst it is accepted that in hindsight the microlight 

pilot was visual with the Sea King, had he called Culdrose on his radio greater SA would have 

been available, especially considering that Culdrose were NOTAM’d [see UKAB Note 2 above] as 

operating SSR-only and would therefore not be able to see the microlight on PSR. 

Summary 

A Sea King and a Pegasus Quantum microlight aircraft flew into close proximity at a position 1.5nm 

North of Camborne, at about 1122 on 26 th June 2013. The Sea King pilot was conducting a postmaintenance 

flight airtest and was in receipt of a Basic Service from Culdrose APR. The Quantum 

pilot was transiting, with a Basic Service from Newquay APR. 

PART B: SUMMARY OF THE BOARD'S DISCUSSIONS 

Information available included pilots’, ATC and relevant operating authority reports. The incident was 

not observable on area radar recording. 

The Board first considered the pilots’ actions. The Sea King pilot was conducting an airtest in VMC 

and was in receipt of a Basic Service from Culdrose who were operating SSR-only due to the fact 

that their primary radar was not serviceable. The Sea King pilot stated that, prior to entering the right 

turn, the observer had been 'eyes in', conducting part of the airtest procedure. Members pointed out 

similarities between this incident and other Airprox in which pilots had been conducting airtests, and 

noted that the increased amount of ‘heads-in’ time associated with the airtest process often reduced 

the capacity for lookout. Considering the reduced capacity for lookout during an airtest, members 

4 Aeronautical Chart ICAO, Southern England and Wales, Edition 39 (2013). 

5 Topographical Air Chart of the United Kingdom, Sheet 7, The West and South Wales, Edition 9 (2013). 

3

commented on the chosen location (in the vicinity of a designated paraglider/microlight winchlaunching 

area), and, although the Quantum was in fact in transit rather than being operated from this 

location, opined that the airtest could sensibly have either been conducted in an area and at a height 

that was better deconflicted from other VFR traffic, or an extra crew member could have been carried 

to improve lookout in what was see-and-avoid airspace. Members also reiterated the benefit of a 

radar based ATS in these circumstances and noted that the Sea King crew were using on-board 

equipment to give them SA on other transponding aircraft. In the event, given that the microlight was 

not equipped with an SSR transponder, it would not have been seen on the SSR-only Culdrose radar 

or in the Sea King. Finally, members also commented that, notwithstanding operational imperatives, 

the combination of challenging weather and lack of appropriate ATS may have presented sufficient 

risk that the airtest could reasonably have been postponed altogether. 

The microlight pilot reported that he had ‘checked NOTAMs’ before take-off, one of which stated that 

Culdrose ‘were not offering a service’ that day, and that he therefore did not seek to obtain an ATS 

from them. Members agreed that it would have been advantageous for the microlight pilot to have 

contacted Culdrose to pass his route details to them so that they, and the aircraft they were 

controlling, could have benefited from the increased SA that this would have provided even though a 

Traffic Service would not have been possible (given that the microlight was not equipped with an SSR 

transponder and that Culdrose were operating SSR-only). However, the Board concluded that the 

microlight pilot had been led to believe that Culdrose ‘were not offering a service’ that day, and so his 

decision to talk instead to Newquay was understandable, and in fact laudable, in that he had 

consciously chosen to communicate his routing and intentions to an ATS unit near his route. 

With regard to the RNAS Culdrose NOTAM, the Board noted that there was no record of a NOTAM 

being issued for RNAS Culdrose on the date of the Airprox; members therefore wondered whether 

the microlight pilot may possibly have read information that had been passed by phone from RNAS 

Culdrose to local operators in accordance with their routine procedures. However, regardless of 

whether by NOTAM or phone call, the situation regarding SSR-only operations had either been 

misinterpreted by the microlight pilot, or had not been clearly conveyed. The Board noted that the 

microlight pilot’s flying instructor had also independently confirmed that ‘Culdrose were not offering a 

service’, so there was clearly ambiguity of some sort. Ultimately, the Board could not reconcile RNAS 

Culdrose’s belief that a NOTAM had been issued when in fact there was no record of such. 

The microlight pilot saw the Sea King at range, was able to maintain visual contact, and took avoiding 

action from the rotor wash when the Sea King pilot turned right to avoid him. The Sea King pilot was 

required to give way but the crew did not see the microlight until just before CPA; the Board therefore 

decided that the cause was a late sighting by the Sea King pilot, and, although effective avoiding 

action had been taken, safety margins were much reduced below normal. 

PART C: ASSESSMENT OF CAUSE AND RISK 

Cause: 

A late sighting by the Sea King pilot. 

Degree of Risk: B. 

ERC Score 6 : 101. 

6 Although the Event Risk Classification (ERC) trial had been formally terminated for future development at the time of the 

Board, for data continuity and consistency purposes, Director UKAB and the UKAB Secretariat provided a shadow 

assessment of ERC. 

4


Date/Time: 18 Jul 2013 0836Z 

Position: 

5130N 00033E 

(7nm SSW of Southend Airport) 

Airspace: Lon FIR (Class: G) 

Reporting Ac 

Reported Ac 

Type: A319 Paramotor 

Operator: CAT Unknown 

Alt/FL: 2000ft NK 

QNH (NR hPa) NK (NK hPa) 

Weather: VMC CAVOK NK 



0ft V/50m H 


NK V/NK H 

NK V/NK H 

PART A: SUMMARY OF INFORMATION 

REPORTED TO UKAB 

Diagram based on radar data 

and pilot reports 

Paraglider 

(not radar derived) 

Reported CPA 0836:58 

NM 

0 1 2 

A020 

A020 

A024↓ 

A319 

↓2000ft 

Southend 

THE A319 PILOT reports positioning for an approach at Southend, level at 2000ft on Southend QNH, 

heading 360° at 210kt, in ‘clear, sunny’ weather. The aircraft was squawking modes 3/A, C and S, 

and the crew had agreed a Deconfliction Service with Southend Radar. When the aircraft was 7nm 

south-south-west of Southend, the crew reports seeing a paramotor with a red canopy, in their left 

10 o’clock position, 50m away, at the same altitude and travelling in the opposite direction. He 

reported seeing the paramotor when it was almost abeam their A319 and, due to the size and relative 

speeds of the aircraft, could not take any avoiding action. 

He assessed the risk of collision as ‘Very High’. 

THE PARAMOTOR PILOT could not be traced and, consequently, no report could be obtained 

THE SOUTHEND RADAR CONTROLLER reports vectoring the A319 for an ILS approach to RW06 

under a Deconfliction Service. When the aircraft was about 8nm away from Southend, on a bearing 

of around 210°, at 2000ft on the QNH of 1027hPa, the pilot reported passing ‘very close’ to a 

‘paraglider’ at a similar altitude. The controller could not see any conflicting returns on the radar 

display, and the pilot did not report taking any avoiding action. 


The weather at Southend at 0820 was recorded as: 

METAR EGMC 180820Z 04005KT 360V080 9999 FEW010 21/15 Q1027 


The Southend ATC Unit Occurrence Investigation reports that the weather conditions were 

good with excellent visibility; there was a little low cloud at 1000ft reported at Southend, but not a 

significant amount, and the A319 pilot reported no cloud in the area of the Airprox. 

1

Southend Radar had identified the A319 using Mode-S and had confirmed that no unknown 

returns were present on his radar display; replay of the radar recording of the incident supports 

this. The A319 was vectored initially on a heading of 350° for right base to RW06, between 2 

other transiting aircraft that were identified and receiving a service. Southend Radar then turned 

the A319 left by 15° onto a heading of 335°. The A319 was provided with a Deconfliction Service; 

the normal deconfliction minima that ATC seek to achieve from unknown traffic are 3000ft 

vertically or 5nm laterally. However, because the paramotor was neither known, nor showing on 

the radar display, ATC intervention was not possible and the A319 pilot was not given any 

warning of the conflicting traffic - it was not possible for the controller to pass either traffic 

information or avoiding action on an aircraft that was not being presented on the radar. 

Stoke microlight site is near to Southend and, within 45 minutes of the Airprox, Southend ATC 

had spoken to the owner, who confirmed that they had no para-gliders or para-motors based 

there, and nothing had yet flown from them that day. 

The radar recording was analysed and, whilst several intermittent primary contacts could be seen 

over a long time-scale, none of them could be correlated with the A319 pilot’s report. The Unit 

asked their technical staff and the radar manufacturer to investigate the performance of their radar 

with a view to improving its performance against small targets. 

The Radar Manufacturer reports that the paramotor was probably detected for a short period of 

time at the raw-radar plot data level, but that it was probably too small to be detected consistently 

by the radar. In order to reduce false radar returns produced by clutter, the equipment has a 

tracker filter, which removes raw-radar plots having a speed of less than 40kt. It is likely therefore 

that the raw-radar plot data did not generate a track on the radar display due to the low detection 

rate cause by the paramotor’s very small radar cross-section and its low speed. 

Southend Unit Recommendations: 

Recommendation 1: Southend ATE should re-engage with the radar manufacturer to see if any 

further optimisation of the PSR elements of the radar can be done to enhance chances of 

detection of very small/slow targets, particularly in areas of known Airprox concern. 

Recommendation 2: Southend Airport continues to seek to obtain CAS as soon as possible in 

order to provide better protection for aircraft flying instrument flight procedures into and out of 

Southend. 

Recommendation 3: Southend Airport to ask regular commercial operators to re-iterate to their 

pilots operating at Southend that not all smaller/slower targets will be detected by modern radar 

systems. 

[UKAB Note 1: These recommendations are not necessarily the view of the UK Airprox Board]. 

CAA ATSI reports that they had access to Southend RTF, area radar recordings, together with 

the written reports from the Southend controller, ATSU and A319 pilot. The A319 was operating 

an IFR flight inbound to Southend Airport and was in receipt of a Deconfliction Service from 

Southend Approach. 

The paramotor was untraced, very likely operating VFR, and not in receipt of an air traffic service. 

At 0835:03, the A319 was 13.1nm south-southwest of Southend Airport. The A319 pilot contacted 

Southend Radar and reported descending to 3000ft on a northerly heading. The controller passed 

traffic information regarding a PA28, co-ordinated at 2000ft in the A319’s 1 o’clock at 2.5nm. A 

Deconfliction Service was agreed, and the A319 pilot reported visual with the traffic. The A319 

was then turned left onto a heading of 350°. 

2

At 0836:00 the A319 had passed abeam the south-bound PA28 and was instructed to descend to 

an altitude of 2000ft, with a left turn onto a heading of 335° for base leg. 

At 0836:50 the Radar controller passed traffic information regarding another PA28: 

Radar: “ [A319)c/s] traffic left er ten o’clock correction half past nine five and a half miles 

passing well down your left hand side is a piper arrow two thousand feet” 

A319: [0837:00]“That’s understood we’ve just had some kind of erm a para-glider or 

something like that passing very very close to our left hand side [A319)c/s]” 

Radar: “Roger nothing ob- seen on radar are you happy to continue on that track” 

A319: “Er affirm he’s passed us now but it was very close [A319)c/s]”. 

At 0837:33 the A319 was given a closing heading for the localiser and continued with the 

approach without further incident. 

The controller reported that there were no unknown returns shown in close proximity to the A319 

at the time of the Airprox, and this was confirmed by a replay of the ATSU radar recording. 

CAA ATSI completed an analysis of the area radar recordings, which did show a probable 

intermittent contact that appeared 20 seconds after the Airprox. This contact appeared 0.25nm left 

of the A319’s radar trail history and was shown for two sweeps of the radar followed by a final 

trace at 0837:58 before the contact faded from radar, as shown in figure 1. 

Figure 1 – Swanwick MRT at 0837:58 (UKAB Note: CPA label should read 0836:58) 

By measuring the distance (0.3nm) between the returns at 0837:18 and 0837:58 (40seconds), the 

ground speed of the unknown contact was calculated as 27knots. At this speed the contact 

would have travelled 0.15nm since the time of the Airprox. This is shown on Figure 1 above and, 

at CPA, the unknown contact was estimated to be around 0.1nm (185m) to the left of the A319 

[UKAB Note 2: this measurement is subject to uncertainty in radar return display inaccuracies and 

should not be considered as definitive]. 

After the Airprox, the ATSU initiated tracing action but the paramotor remained untraced. 

3

The ATSU, in consultation with the radar manufacturer, reported that the unknown 

paramotor was too small in terms of radar cross-section, and was travelling too slowly to 

be displayed by Southend Radar. The radar processing system ‘tracker’ filter removes raw-radar 

plots having a speed below 40 knots in order to reduce the false alarm clutter. The calculated 

ground speed of the unknown contact was 27 knots. The Southend radar detection system is 

approved and compliant with the requirements of CAP670 ATS Safety Requirements. 

Following increased operations from Southend since April 2012, London Southend Airport has 

undertaken a formal consultation (conducted between 20 September 2013 to 19 December 2013) 

to seek to re-establish Controlled Airspace around Southend Airport. 

ATSI Analysis: The A319 was in receipt of a Deconfliction Service; a surveillance-based service 

under which controllers will provide surveillance-derived traffic information. However, the 

avoidance of other traffic is ultimately the pilot’s responsibility and the provision of the service is 

constrained by the unpredictable nature of the environment. 

Because of the paramotor’s small radar cross-section and slow speed it was not displayed by the 

Southend Radar system. As a result there was no specific surveillance-derived information 

regarding the paramotor, and the Southend Radar controller was not able to provide tactical 

deconfliction advice or warning to the A319 pilot. 

Within Class G airspace, regardless of the service being provided, pilots are ultimately responsible 

for collision avoidance 

Summary 

The Airprox occurred at 0836:58, 8.4nm south-west of Southend Airport, within Class G airspace, 

between an A319 and an untraced paramotor. The unknown paramotor was too small and too slow 

to be displayed by the Southend Radar system and, in the absence of surveillance-derived 

information, the Southend radar controller was therefore unable to provide any deconfliction advice. 


Information available included a report from the crew of the A319, transcripts of the relevant RT 

frequencies, radar photographs/video recordings, a report from the air traffic controller involved and a 

report from the ATC operating authority. 

The Board noted that the Airprox occurred in Class G airspace, for which see-and-avoid was the 

primary method of collision avoidance. Both aircraft were equally entitled to be in that location, and 

therefore the pilots shared equal responsibility for collision avoidance. Notwithstanding, the Board 

observed that the paramotor pilot had probably been unwise to position himself at 2000ft so close to 

the approach track for Southend’s active RW06, and at a location which would have been frequented 

by aircraft routing to Southend for IFR approaches. The gliding member concurred, and opined that 

the positioning of the paramotor possibly indicated a low-level of aviation awareness by its pilot. 

Unfortunately, because the paramotor pilot could not be traced, the Board were unable to explore 

further this aspect. As an aside, the Board also noted that the fact that the pilot had not come 

forward himself (after what must have been a frightening event), was an additional indicator as to his 

likely inexperience in aviation matters. 

The airline members stated that, in this case, TCAS would not have been able to provide protection 

because the paramotor would not have been equipped with an SSR transponder or other electronic 

conspicuity aid. They also commented on the difficulty of seeing such small aircraft, especially from 

the cockpit of a much faster moving large airliner. Noting that Southend was applying for controlled 

airspace to be established around the airport, the airline members also wondered how likely it would 

be that, given the paucity of training and regulation of paramotor pilots, they would understand the 

requirements of controlled airspace. Even with controlled airspace established around airfields, VFR 

traffic operating within and around its margins needed to understand where other traffic was likely to 

4

e encountered, and what their associated routeing might be. The Board were informed that 

paramotor pilots do not require a licence to fly, although they are still required to comply with the 

Rules of the Air. The British Hang Gliding and Paragliding Association (BHPA) oversees pilot and 

instructor training standards for Free Flying, which includes the operation of paramotors, but there is 

no requirement for a paramotor pilot to join the BHPA. As a result, the pilot involved in this Airprox 

could well have been entirely independent, and could possibly have received very little training in Air 

Law and airmanship matters. 

The Board did not have a report from the paramotor pilot but members were of the unanimous 

opinion that he would have seen and heard the A319 pass close by. The Board could not establish 

whether the paramotor pilot took avoiding action but it was clear that the A319 pilot had not seen the 

paramotor early enough to do so himself. Both pilots were equally responsibility for collision 

avoidance 1 , and the A319 pilot was required to give way 2 . The Board therefore decided that the 

cause was an effective non-sighting by the A319 pilot. In assessing the risk, Board members noted 

that the A319 crew had not had time to take any avoiding action, and that the radar analysis 

supported the pilot’s estimate of horizontal separation. The Board were therefore unanimous in 

agreeing that separation had been reduced to the minimum, and that the Degree of Risk was 

Category A. Noting the concerns raised about ensuring the competency and training of paramotor 

pilots, the Board also decided to recommend that the CAA reviews the regulation and licensing of 

paramotor glider pilots. 


Cause: 

Effectively, a non-sighting by the A319 pilot. 

Degree of Risk: A. 



The CAA reviews the regulation and licensing of paramotor glider pilots. 


2 ibid., Rule 9 (Converging). A paramotor is classed as a glider in the ANO. 




5


Date/Time: 20 Jul 2013 1537Z (Saturday) 

Position: 

52 04N 00017W 

(2nm South-east of Biggleswade) 

Airspace: London FIR (Class: G) 

Reporting Ac 

Type: Vigilant PA28 

Reported Ac 

Operator: HQ Air (Trg) Civ Club 

Alt/FL: 1800ft 1500 

QFE (1019hPa) QFE (1019hPa) 

Weather: VMC CAVOK VMC CAVOK 

Visibility: 10km 10km 


100ft V/0m H 


NR V/


The weather at Cranfield at 1520 was notified as: 

METAR EGTC 201520Z 04012KT 9999 SCT018 21/16 Q1023 



Analysis of the radar recording at 1536:20 shows the Vigilant 1.5nm north-east of Henlow, with no 

Mode C indication available, flying north-east, with the PA28 in its 5.30 position, 0.4nm behind, 

indicating an altitude of 1000ft and following a similar track. The PA28 turns slightly left to track 

north and, at 1536:37 has climbed from 1000ft to indicate 1300ft, still 0.4nm behind the Vigilant. 

At 1536:46 the PA28 manoeuvres right and then left, remaining in the Vigilant’s rear right quarter, 

indicating 1400ft, before its Mode C disappears when it is 0.2nm from the Vigilant. Twenty 

seconds later the PA28’s Mode C returns, indicating 1700ft; the Vigilant is 0.2nm ahead of the 

PA28. At 1537:15 the Mode C of the PA28 continues to indicate 1700ft before disappearing with 

the PA28 0.1nm directly behind the Vigilant. At 1537:40 the radar returns have merged, there is 

no measurable horizontal separation but the PA28’s Mode C has returned and indicates 2000ft. 

The PA28’s radar return moves ahead of the Vigilant’s at 1537:44, and then continues to pull 

away from it indicating 2000ft. 

The Vigilant had right of way because it was being overtaken by the PA28, which was required to 

overtake on the right. 1 The PA28 pilot reports that the student turned their aircraft to the right and 

estimated that they achieved 200ft H separation. Although the PA28 is shown on the radar replay 

in the Vigilant’s 5-5.30 position for some of the time as it approaches, the radar returns merge 

with no discernible horizontal separation. Furthermore, the PA28 pilot had the responsibility to 

‘keep out of the way’ of the Vigilant until the aircraft were clear of each other. 2 Finally, an aircraft 

which is obliged to give way to another aircraft is required to avoid passing over or under the other 

aircraft, or crossing ahead of it, unless passing well clear of it. 3 The PA28 pilot reports losing 

sight of the Vigilant during the overtaking manoeuvre, however, his student was able to keep it in 

sight and he reports that he remained well clear. At the point that the radar returns merge, the 

PA28’s Mode C indicates 200ft above the reported altitude of the Vigilant, which is commensurate 

with the PA28 pilot’s report, and close to the Vigilant pilot’s report. 

Comments 

HQ Air Command 

The Vigilant pilot faced a quandary in this instance; he knew a faster aircraft was approaching that 

would always be difficult to see, but that the rules of the air require him to maintain heading so the 

overtaking aircraft can avoid. However, one could argue that the Rules of the Air only apply if 

aircraft are visual with another, conflicting aircraft, in which case the practice of making regular 

changes of heading might have allowed the opportunity to acquire the following aircraft. His 

report indicates he adopted an appropriately defensive mindset but that the actions of the PA28 

crew did not ensure a safe and orderly overtake. 

Summary 

The Airprox occurred in Class G airspace, 2nm South-east of Biggleswade, between a Vigilant motorglider 

and a PA28, which was overtaking it. Both aircraft were carrying out instructional sorties and 

were flying VFR in VMC without an air traffic service. 

1 Rules of the Air 2007, Rule 11, para 1. 



2


Information available included reports from the pilots of both ac and radar photographs/video 

recordings. 

The GA and gliding members lead the discussion and noted that the PA28 instructor pilot had seen 

the Vigilant early on as his aircraft had caught up with it, but had then allowed his student to fly into a 

position where the instructor could no longer see the Vigilant as they overtook it. Whilst the student 

had apparently maintained visual contact with the Vigilant throughout, Board members were clear 

that it was the instructor who had the responsibility to ensure adequate separation was maintained 

throughout the overtaking manoeuvre. The GA members noted that this was the latest in a series of 

Airprox where pilots have allowed too little separation when overtaking, or have seen another aircraft 

early on but still not taken timely and decisive action. The Board agreed that this observation would 

make a good topic for further education throughout the GA community, and particularly within the 

prospective 2014 Airprox edition of the CAA’s ‘Clued Up’ magazine. 

Turning to the actions of the Vigilant pilot, the Board felt that he had done well to build up and 

maintain situational awareness regarding the PA28. The Board postulated that he may have been 

torn between maintaining his track whilst being overtaken and manoeuvring to maintain positive 

visual contact with the PA28 as it overtook. Some members opined that there would have been 

some merit in the Vigilant pilot making some small turns for reasons of both lookout and to encourage 

a wider berth by the PA28 pilot; in other circumstances, whilst maintaining the same general track, a 

small amount of movement might also have increased the Vigilant’s visual conspicuity. 

The Board unanimously agreed that the cause of the Airprox was that the PA28 pilot flew close 

enough to cause the Vigilant pilot concern during the overtaking manoeuvre. Noting that the student 

in the PA28 had maintained visual contact with the Vigilant, the Board agreed that effective actions 

could at all times have been taken to prevent a collision, and decided that the Degree of Risk was C. 


Cause: 

The PA28 pilot flew close enough to the Vigilant to cause its pilot concern. 

Degree of Risk: C. 

ERC Score: 4 20. 



assessment of ERC 

3


Date/Time: 20 Jul 2013 1541Z (Saturday) 

Position: 

5203N 000 13W 

(3nm SE of Biggleswade) 


Reporting Ac 

Reported Ac 

Type: Vigilant Hurricane 

Operator: HQ Air (Trg) Unknown 


QFE (1019hPa) 


Visibility: 10km NR 


0ft V/20m H 


NK 

NK 


THE VIGILANT PILOT reports flying VFR, with a student, in a white motor-glider, displaying orange 

hi-visibility patches, with the strobe, navigation and landing lights turned on. He had selected 

transponder mode 3/A code 7000 (modes C & S were not fitted), and was in radio contact with 

Henlow Radio. The student was on a work-up sortie designed to lead to the first off-circuit solo sortie 

and had been briefed to operate ‘as if solo’. They discussed recent Airprox events in the area and 

the student was tasked with selecting a suitable operating area; they elected to operate to the east of 

the A1 to the south of Biggleswade, allowing a suitable margin from the line-feature to allow other 

pilots to navigate along it safely. 

The aircraft was climbed to 2000ft; after crossing the A1 the instructor was scanning to the right and 

noticed a ‘fast-moving aircraft’ approaching from behind. He identified it as a Hurricane, which 

appeared to ‘formate’ in a position around 20m from his starboard wing-tip for ‘a couple of seconds’ 

he reported; this impression was strengthened as the Vigilant pilot recalls seeing the Hurricane pilot 

look across towards his aircraft. The Instructor then saw the Hurricane dive towards what he 

believed was the FARR Festival, at Bygrave Woods near Newnham, before commencing a series of 

aerobatic manoeuvres. 

He assessed the risk of collision as ‘Low’. 

THE HURRICANE: The radar recording showed a primary track, travelling at an appropriate speed 

for a Hurricane, but it faded 0.3nm from the Vigilant and could not be re-identified. The operators of 

Hurricanes in the area were contacted; the Battle of Britain Memorial Flight and the Shuttleworth 

Collection both confirmed that their Hurricanes were either on the ground or in another location at the 

time of the Airprox. Another local operator, with a Hurricane airborne at the time, declined to cooperate 

with the UKAB and stated that he did not wish to be contacted again regarding the matter. 


The weather at Cranfield at 1550 was notified as: 

METAR EGTC 201550Z 02012KT 9999 SCT022 20/16 Q1023 



Hurricane 

(Primary radar 

return only) 

Hurricane return 

fades at 1541:11 

Vigilant 

2000ft alt 

CPA 1541Z 

NM 

Vigilant 

at 1541:11 

0 1 2 

Newnham 

1



Analysis of the radar recording shows the Vigilant operating 3nm to the north-east of Henlow, 

tracking east with no mode C indication available. The aircraft manoeuvres left and right twice, 

and then crosses the A1 just before the reported time of the Airprox. 

A primary radar return appears 3nm to the north of Henlow, moving in a steady right-hand curving 

turn towards the Vigilant. The return crosses the A1 and then disappears from the recording 

0.3nm behind and slightly to the right of the Vigilant’s return. Primary returns can then be 

observed twice, ahead of the Hurricane’s track, consistent with its track speed, around 1nm to the 

north west of Newnham, but cannot be positively correlated with the Hurricane’s previous radar 

returns. 

The Vigilant had right of way because it was being overtaken by the Hurricane, which was 

required to overtake on the right. 1 The Vigilant pilot’s report and the radar recording indicate that 

the Hurricane passed down the right-hand side of the Vigilant. The Hurricane pilot had the 

responsibility to ‘keep out of the way’ of the Vigilant until the aircraft were clear of each other. 2&3 

The Hurricane’s radar return fades 0.3nm from the Vigilant’s return with no Mode C information 

available for either aircraft; given the tracks of the aircraft it is possible that the actual CPA was 

closer, but the Vigilant pilot’s report of 20m H cannot be corroborated by the radar recording. 

Comments 


Without the report from the Hurricane pilot, assessing this Airprox is much more difficult and it is 

hard to identify what might be done to prevent a recurrence. The Hurricane pilot had the 

responsibility to avoid the Vigilant under the Rules of the Air and either did not see it or chose to 

fly close enough to cause concern. For their part, the Vigilant crew appear to have had 

reasonable situational awareness, sighting the Hurricane as it approached them initially from the 

outside of their turn and then from behind. 

Summary 

The Airprox occurred in Class G airspace, 3nm south-east of Biggleswade, between a Vigilant motorglider 

and a Hurricane, which overtook it. The Vigilant pilot was carrying out an instructional sortie 

and was flying VFR in VMC without an air traffic service. The Hurricane could not be definitively 

traced so the views of its pilot could not be included in this analysis. 


Information available included a report from the Vigilant pilot and radar recordings. 

The Board commented that, despite the unique nature of the aircraft, it was unfortunate that the 

Hurricane pilot could not be definitively identified. They also commented that it was highly unhelpful 

that a Hurricane pilot who had been airborne at the time, and who could have been flying in that area, 

chose not to co-operate with the Board, even to rule himself out of the investigation. Whilst it was still 

possible to assess the Airprox using the Vigilant pilot’s report supported by the radar data, the Board 

was clear that it would have been much easier to identify lessons and compile a more accurate 

analysis of the event if a report from the Hurricane pilot concerned had been obtained. 

1 Rules of the Air 2007, Rule 11, Overtaking, para 1. 

2 Rules of the Air 2007, Rule 11, Overtaking, para 2. 

3 Rules of the Air 2007, Rule 8, Avoiding Aerial Collisions, paras 2 & 3. 

2

It was evident to the Board that the Vigilant pilot had seen the Hurricane early and had maintained his 

course and speed to allow the Hurricane to overtake. The Board members also noted that the 

Vigilant pilot had reported that the Hurricane pilot appeared to look across at the Vigilant. Although 

the radar shows a significant speed differential between the aircraft, the Hurricane return disappears 

before the likely CPA, and the Board opined that the geometry of the encounter, and the fact that the 

Hurricane reportedly appeared to briefly stabilise near the Vigilant, meant that it was very likely that 

the Hurricane pilot had also seen the Vigilant. For his part, the Vigilant pilot remained in visual 

contact throughout, and ready to take avoiding action if required, even though the awareness and 

intentions of the Hurricane pilot were unknown. Consequently, the Board assessed the degree of risk 

as C; there was no risk of collision. It was unanimously agreed that the cause of the Airprox was that 

the Hurricane pilot flew close enough to the Vigilant to cause its pilot concern. 


Cause: 

The Hurricane pilot flew close enough to the Vigilant to cause its pilot 

concern. 






3



A320 


Position: 

5214N 00111W 

(4nm NW Daventry) 

Airspace: Daventry CTA (Class: A/C) 

Reporting Ac 

Type: A320 DH8D 

Operator: CAT CAT 

Reported Ac 

Alt/FL: FL200 FL190 

Weather: IMC KLWD VMC CLAC 

Visibility: Nil 10km 


400ft V/2nm H 


400ft V/6.2nm H 

1400ft V/2.3nm H 

400ft V 

NM 

10 

5 

0 

F205 

F201 

F199 

F202 

CPA 1906:42 

1400ft V/2.3nm H 

F203 

F189 

F190 

06:30 

F195 

F197 

06:18 

F198 

05:54 

06:06 

DH8 


THE A320 PILOT reports inbound to Heathrow (LHR), under the control of London ATC Centre. Anticollision 

and navigation lights were illuminated, and SSR Modes C and S were selected. While 

deviating for weather, and in level flight at FL200, ATC instructed an immediate left turn for avoiding 

action. With Auto Pilot (AP) engaged, and turning left in response to the ATC instruction, he heard a 

TCAS RA climb instruction. AP and Flight Director (FD) were disengaged and a climb initiated in 

response to the RA. The aircraft climbed approximately 309ft and turned left 40°. From the TCAS 

read-out, he estimated that the other aircraft was never closer than 400ft. He did not see the other 

aircraft as he was in cloud and it was behind his aircraft. The other aircraft appeared suddenly on the 

TCAS display behind his aircraft and remained there until it disappeared from the display. 

He perceived the severity of the incident as ‘Medium’. 

THE DH8D PILOT reports inbound to Birmingham (BHX). Position lights and white strobes were 

illuminated, the landing lights were selected off. The aircraft was cleared to FL90 on descent into 

BHX. There was a fair amount of CB activity at approximately 20nm SE of Honiley (HON) so the 

aircraft was descended at 500fpm to stay above a build-up. Passing FL195, a right turn was 

requested and approved to avoid a CB that was on the aircraft’s track. Passing FL190 a TCAS TA 

was received followed closely by an RA. The AP was disengaged and the TCAS commands were 

followed. Concurrent with the TCAS RA, ATC gave an instruction to turn immediately onto a heading 

of 300° (he thought), which was carried out immediately. A similar instruction was heard to have been 

given to another aircraft immediately prior to this. Once clear of the conflict a report was made over 

the radio and clarification of any further instructions was sought. 


THE LTC WELIN CONTROLLER reports that there was a lot of weather avoidance being carried out 

in his sector. He had co-ordinated the DH8D to enter Cowly’s airspace from HEMEL. Because the 

Cowly controller had aircraft inbound to Bovingdon (BNN), he descended the DH8D to FL170 i.e. 

beneath all the LHR traffic in the Cowly sector. He then issued further descent to the aircraft to FL90. 

1

When N of DTY, inbound to HON, the pilot requested a turn onto heading 335° to avoid weather. 

Having approved this request, he noticed that the A320 was level at FL200 and the DH8D was 

passing FL197 and seemed to have stopped descending. He issued an avoiding action turn onto 

heading 280° and the Cowly controller also gave the A320 avoiding action. Both aircraft received 

TCAS RAs. He reported there was no loss of separation. 

THE LTC COWLY CONTROLLER reports weather avoidance was taking place. He was monitoring a 

trainee on TC Cowly when the A320, descending to FL200, requested a weather avoidance heading 

of 135°. This was approved and notified to the Welin controller who had the DH8D heading 335°, 

descending to FL170. A short time later the STCA flashed red when the two aircraft were about 10nm 

apart with the A320 level at FL200 and the DH8D observed at FL197. He took over the RTF and gave 

avoiding action to the A320 (left turn onto 090° degrees (he thought) and traffic information (TI) was 

issued). The pilot reported a TCAS RA and was seen to be climbing. The DH8D was also given 

avoiding action (by TC Welin) and reported a TCAS RA. There was no loss of separation. 


Required minimum separation between the subject aircraft was 3nm horizontal and/or 1000ft vertical. 


CAA ATSI 

An Airprox was reported in Class C airspace by an Airbus A320 (A320), descending to FL200 in 

the vicinity of Daventry when it received a TCAS RA against a Bombardier DHC-8-402 (DH8D), 

which was descending into Class A airspace to FL90. ATSI had access to both pilot reports, 

reports from the Cowly and Welin controllers, recorded area surveillance and transcription of 

frequencies 121.025MHz and 130.925MHz, together with the unit report. 

The A320 was operating IFR on a flight inbound to LHR, displaying SSR code 7664 and was in 

receipt of a Radar Control Service from the London Terminal Control (LTC) Cowly sector on 

frequency 121.025MHz. 

The DH8D was operating an IFR flight inbound to BHX, displaying SSR code 4406 and was in 

receipt of a Radar Control Service from the LTC Welin sector on frequency 130.925MHz. 

Training was in progress on the Cowly sector. There was a high level of Thunderstorm activity in 

the area which brought a high level of workload complexity for the Welin controller. 

At 1900:15 the DH8D pilot contacted the Welin controller descending to FL220 heading 310° and 

was given descent to FL170. At 1902:15 the DH8D was given further descent to FL90. 

At 1903:32 the A320 pilot contacted the Cowly controller descending to FL200 heading 135° due 

to weather. The Cowly controller advised Welin that the A320 was avoiding weather and the A320 

pilot subsequently asked for a 5° right-turn heading 140°, which was approved by Cowly. 

At 1905:13 the DH8D pilot requested a 20° right turn onto heading 335° to avoid weather which 

was approved by the Welin controller (Figure 1). The two aircraft were 19.2nm apart and the 

DH8D was 2100ft below the A320, however, the DH8D was only descending at a rate of 500fpm 

while the A320, descending to FL200, was descending at a rate of 2000fpm. 

2

Figure 1 

At 1906:00 the two aircraft were 10nm apart with the A320 descending through FL204 for FL200 

and the DH8D was passing FL198 for FL90. The Welin controller instructed the DH8D to expedite 

descent due to traffic above. Low level STCA activated. 

At 1906:05 High level STCA activated. The Cowly controller issued avoiding action to the A320 to 

turn left heading 095°. The Welin controller issued avoiding action to the DH8D to turn left heading 

290°. At 1906:20 the A320 reported receiving a TCAS RA (Figure 2). 

Figure 2 

At 1906:22 the two aircraft were 4.1nm and 1000ft apart (Figure 3). 

3

Figure 3 

A high level of thunderstorm activity caused both aircraft to deviate off track to avoid weather and 

into closer proximity with each other. Also, due to the thunderstorm activity, the DH8D was 

descending at a significantly slower rate than the A320. This was not noticed by the Welin 

controller. 

Summary 

An Airprox was reported following TCAS RAs being received by an A320 and a DH8D.The TC Welin 

controller did not notice that the descent rate of the DH8D was significantly less than that of the A320 

and the two aircraft came into closer proximity than anticipated by the Welin controller. Both the 

Cowly and Welin controllers issued avoiding action following low level STCA. 

PART B: SUMMARY OF THE BOARD’S DISCUSSIONS 

Information available included reports from the pilots and air traffic controllers involved, radar 

recordings, transcripts of the relevant RT frequencies and reports from the appropriate ATC and 

operating authorities. 

The Board first considered the actions of the Welin and Cowly sector controllers. Although the 

Airprox occurred within the Cowly sector, the Welin controller was in control of the DH8D, having coordinated 

it into the Cowly sector. The Board noted that both controllers had reported conducting 

significant weather avoidance within their sectors, which increased their respective workloads 

considerably. However, civil ATC members commented that, in conditions when aircraft may ask for 

heading changes for weather avoidance, it was prudent to ensure vertical separation as the 

fundamental method. The Board opined that in deciding to clear the DH8D to descend through the 

level of the A320, the Welin controller should have been more pro-active in monitoring the DH8D’s 

descent profile. In this respect, the clearance issued by the Welin controller was not ‘fail-safe’ but 

relied on his ability to monitor the aircraft in a busy traffic environment. One ATC member thought 

that the Cowly controller could have stopped the A320’s descent at FL210, when the aircraft were 

about 19nm apart and the DH8D was passing FL201. However, the Board considered that it was the 

Welin controller’s responsibility to ensure separation between the two flights. 

Turning to the actions of the pilots, the Board noted that both aircraft were being operated in 

accordance with their clearances, albeit the DH8D was making a ‘slow’ descent at a rate of 500fpm to 

4

stay above a cloud build-up. Notwithstanding that this is within the approved minimum descent rate 1 , 

the Board opined that the DH8D pilot could usefully have alerted the Welin controller that he was 

descending more slowly than he might have otherwise expected. A Controller member commented 

that, in his recent experience, it is becoming more prevalent for aircraft to descend at a slower rate 

than previously expected, which can affect controller planning. It was pointed out that this may be 

due to the use of ‘economy’ speeds and that this might need to be factored into controllers’ future 

strategies for sequencing aircraft in the terminal phases of their flights. 

The Board decided that, even though separation was subsequently achieved through a combination 

of avoiding action turns, and the pilots following their respective TCAS RAs, it was the Welin 

controller’s responsibility to ensure the fail-safe descent of his DH8D through the A320’s level; 

therefore, the Board concluded that the cause of the Airprox was that the Welin controller allowed the 

DH8D to come into conflict with the A320. The Board members were unanimous in considering that 

the remaining safety barriers had been effective and that, in the end, there was no collision risk; they 

therefore agreed a risk assessment of Category C . 


Cause: 

The TC Welin controller allowed the DH8D to come into conflict with the 

A320. 

Risk: C. 


1 UK AIP ENR 1.1, Paragraph 3.2.2.4.1: Minimum Rates of Climb and Descent 




5



Position: 

5218N 00049W 

(Sywell) 


Reporting Ac 

Reported Ac 

Type: LS8 glider Light aircraft 

Operator: Civ Pte Unknown 


NK (1010hPa) 

Weather: VMC CLBC NK 

Visibility: >20km NK 


50ft 


NK 

NK 

Initially reported 

aircraft track 

Previously faded PSR 

Group of PSR 

tracking northwards 

Diagram based on 

radar and GPS data 

LS8 

CPA 1301:53 

0 2 4 

NM 


THE LS8 PILOT reports circling in a thermal, just to the west of Sywell. He was operating under VFR 

in VMC and was not in receipt of an ATS, although he was ‘talking to Sywell’. The white glider was 

not fitted with an SSR transponder. The glider pilot was ‘talking to Sywell as they had a NOTAM’ 1 and 

‘he was only just above the ATZ’. He believed that ‘powered pilots were aware of his position’. Whilst 

circling right at 50kt he saw a white low-wing, single-engine aircraft, with winglets, approaching from 

the south in level flight, that flew ‘straight through the circle in which he was flying’. He dived to take 

avoiding action. The other pilot ‘put in a climbing orbit but did not speak to Sywell’. 


A LIGHT AIRCRAFT PILOT, flying a high-winged C152, was traced from radar recordings and an 

Airprox form was completed by him. He did not recall proximity to another aircraft during his flight. 

Subsequent scrutiny, as detailed in ‘Analysis and Investigation’ below, established that he was not 

the other pilot involved. The pilot of the other aircraft could not be traced. 


The weather at Cranfield was recorded as follows: 

METAR EGTC 261250Z 28008KT 260V350 9999 FEW040 20/10 Q1030 



Both reporting and reported pilots submitted GPS track logs of their flights. The LS8 pilot reported 

that he believed his avoiding action occurred at 1301:53, based on an uncharacteristic decrease 

in altitude and increase in airspeed, recorded in his GPS log, as he dived to the right. At that time, 

the C152 pilot was approximately 1nm south-east of the LS8, see Figure 1 below. 

1 Aerobatic practice up to altitude 5000ft. 

1

Figure 1: GPS tracks at 1301:53 with GPS status 

The C152 crossed the LS8’s historical track at 1300:40 (at point A on Figure 1), at which point the 

LS8 pilot was established in the left hand orbit shown just to the north of his position in Figure 1. It 

was therefore determined that the C152 was not involved in the Airprox. The fact that the initially 

reported light aircraft was high-wing rather than the glider pilot’s reported low-wing aircraft with 

winglets corroborated this analysis. Subsequent analysis of the radar recording showed a number 

of primary only returns in the vicinity of the LS8 pilot’s track. None of these returns were persistent 

enough to enable tracing of the other pilot. 

Both pilots were equally responsible for collision avoidance 2 and the pilot of the reported light 

aircraft was required to give way 3 . 

Summary 

An LS8 glider and a light aircraft flew into proximity, 1nm to the west of Sywell, at about 1302 on 26 th 

July 2013. The light aircraft pilot could not be traced. 


3 ibid., Rule 9 (Converging). 

2


Information available included a report from one of the pilots, radar video recordings and GPS track 

logs. 

The Board first considered the LS8 pilot’s actions. The LS8 pilot reported he was approaching the 

altitude at which he would have to make a decision whether to land at Sywell. He was also aware of 

the Sywell NOTAM, and had established RT contact with the FISO, actions for which the Board 

commended him. Turning to the unidentified aircraft, it appeared from the glider pilot’s reported 

altitude and estimation of CPA that it was flying within the bounds of the Sywell NOTAM, but was 

apparently not in contact with Sywell. Members noted that the unidentified aircraft reportedly had 

winglets, denoting a level of design and build that might be accompanied by fitment of an SSR 

transponder, yet there were no SSR responses. Although SSR fitment could not be determined in 

this particular instance, the Board reiterated the value of ensuring that, if fitted, SSR should be 

selected on so that TCAS and PowerFLARM equipped aircraft might gain situational awareness from 

this electronic conspicuity aid. 

After some discussion the Board concluded that, although there had clearly been a conflict of flight 

paths as reported by the glider pilot, they were faced with such a paucity of information that a 

meaningful analysis of risk could not be accomplished. 


Cause: Confliction in Class G. 

Degree of Risk: D. 

ERC Score 4 : 

N/S. 




3



Position: 

5212N 00137W 

(Wellesbourne Mountford Airfield 

- elevation 159ft) 

Airspace: Wellesbourne ATZ (Class: G) 

Reporting Ac 

Reported Ac 

Type: PA18 R44 Helicopter 

Operator: Civ Trg Civ Trg 

Alt/FL: NK 5-10ft 

NK 

NK 

Weather: NK VMC CLBC 

Visibility: NK 10km 


10ft V/50m H 


NR 

Not seen 


THE PA18 SUPER CUB PILOT reports she was an instructor on a training flight at Wellesbourne 

Mountford (Wellesbourne) airfield. The R44 was on final approach to Heli landing point "Whiskey" 

whilst her PA18 was on final approach to RW18 grass. Both aircraft’s instructors had called "Final" 

for their respective landings; the trajectory of the R44 should normally have been outside the 

protected zone for fixed-wing traffic. As her PA18 aircraft approached the threshold and commenced 

the flare, the R44 deviated from the helicopter circuit and flew in a descending profile directly over 

the grass RWY ahead of her; the R44 appeared to reduce forward velocity and continued to descend 

such that there was no opportunity for her to go around. Continuing the ground roll on the grass 

RWY could have resulted in the PA18 passing underneath the R44, or striking it if it descended 

further. The pupil in the PA18 therefore started to steer the aircraft to the left to exit the grass and to 

avoid the helicopter. She then took over, steering the PA18 through a gravel margin onto the main 

RW. A ground-loop to the right ensued, with the PA18 re-entering the grass RWY through the gravel 

trap once more. She regained sufficient control to pick up the left (down-going) wing approximately a 

foot above the ground, thus avoiding potential serious damage to the aircraft. The PA18 was brought 

to a halt pointing 180° from the initial landing direction. 

THE R44 PILOT reports that the blue and silver helicopter had strobe lights illuminated and was 

squawking Mode C. She was supervising a Proficiency Check local flight from Wellesbourne airfield. 

Her candidate had been given a simulated emergency and a final call was made for helicopter 

aiming point Whiskey. However, the candidate did not make an approach directly to Whiskey, he 

made an approach to the hover ¾ of the way up the grass that runs alongside the west of RW18. 

She did not hear a fixed-wing aircraft call final for RW18, and therefore did not realise there would be 

a conflict. The candidate came to a hover taxi and continued a short distance to turn left down the 

grass to aiming point Whiskey, moving clear of the RW. At this point she was unaware that an 

Airprox had occurred. As the R44 approached Whiskey, the FISO contacted her informing her to 

make a radio call if she needed to use the grass alongside RW18. Within her report she commented 

that she had flown from Wellesbourne not only through her training but also as an 

instructor/examiner. As the UK AIP does not indicate a grass RWY at Wellesbourne, and never 

having experienced the grass area being used as a RW, she did not expect fixed-wing aircraft to 

land on it. The FISO said he had tried to get her attention but thought his transmission may have 

been ‘stepped on’ by other aircraft. 

R44 

CPA 1015 

Diagram based on pilot reports 

Not to Scale 

Point ‘Whiskey’ 

PA18 

RW18 Grass 

1

THE WELLESBOURNE FLIGHT INFORMATION OFFICER (FISO) reports that a PA18 was 

carrying out 1000ft right-hand circuits using the grass strip adjacent and to the west of RW18/36. The 

RWY is not licensed or marked out, but the operator had approval from the airport authority to use 

the grass for landings and take offs on the basis that it was not to be used at the same time as the 

adjacent tarmac RW18/36. An R44 helicopter was carrying out standard circuits to the west of RW18 

at 600' and using point Heli 'W' as an aiming point, thus keeping the helicopter away from the active 

runways. When the PA18 reported final for RW18 grass he responded 'Land at your discretion on 

the grass'. The R44 reported final for Heli 'W', which he acknowledged. He later noticed that the 

helicopter was getting very close to the PA18 after it had touched down on the grass and he asked 

the helicopter to move away to the right. There was no reply. At this moment the PA18 veered left 

and entered a ground loop to avoid the helicopter. Helicopters are expected to ask to use the grass 

strip adjacent to the runway due to possible conflictions. 


The Birmingham weather and an unofficial Wellesbourne observation were: 

METAR EGBB 241020Z 19009KT 160V220 9999 SCT022 22/15 Q1014= 

Observation EGBW 241025Z 23007KT 9999 SCT030 22/15 Q1014= 

The Wellesbourne ATZ consists of a circle 2nm radius centred at 521132N 0013652W on RW18/36 

and extending to a height of 2000ft above aerodrome level (elevation 159ft). 

The grass runway is not promulgated in the UK AIP, and is only available un-licensed for locallybased 

‘tail-dragger’ aircraft in conditions when the crosswind component precludes the use of the 

asphalt RW18. Prior permission from the Aerodrome Authority is required, together with a full briefing 

and inspection of the grass area prior to use. The grass RW18 consists of a strip approximately 35m 

wide, adjacent to the west side of the asphalt runway, as highlighted in yellow in Figure 1 below. 

Figure 1: Grass RW18 highlighted in yellow. 

The helicopter circuit pattern is published on the Wellesbourne website 1 ; an extracted copy of the 

circuit, together with the helicopter aiming spot whisky (Heli ‘W’), is shown in Figure 2 below. 

1 http://www.wellesbourneairfield.com/dataandmap.htm 

2

Figure 2 – Extracted from Wellesbourne showing helicopter circuit - RW18. 

The Wellesbourne FISO Manual of Local Instructions 2 , states: 

Standard Procedures and local instructions will apply to all aircraft when flying within the 

Aerodrome Traffic Zone. 

Non-standard procedures required for training purposes will only be permitted when the traffic 

situation allows... 

… Traffic information will be given to aircraft in the air, where appropriate... 

Helicopter pilots will be advised by the FISO of the helicopter circuit height 600ft QFE circuits to 

align with fixed wing circuit directions, based on helispots Echo and Whisky. 

The Wellesbourne Aerodrome Manual 3 states: 

A Pilots Order Book is kept in all flying schools and gives details of procedures and restrictions 

relating to the operation of aircraft at Wellesbourne and details of current legislation.’ 

The following instructions to pilots are promulgated in the Aerodrome Directory of the 

Aerodrome Section of the UK AIP. 

(a) Circuit height 1000ft agl for fixed wing aircraft, 600ft agl for helicopters 

(b) Runway 18 and 23 right hand circuits… 

(f) Helicopter circuits inside fixed wing circuits avoiding local villages. 


CAA ATSI Analysis 

CAA ATSI had access to area radar recordings together with written reports from the FISO and the 

pilots of both aircraft. Wellesbourne are not required to record RTF and therefore no RTF 

recording was available. Area radar recordings did not show the Airprox event. 

2 Paragraphs 2 and 2.5 

3 Paragraphs 3.8.1 and 4.15.1 

3

The FISO reported it had been a busy day. 

The PA18 was carrying out visual right-hand circuits on the RW18 grass strip at 1000ft, meanwhile 

the R44 helicopter was carrying out right-hand helicopter visual circuits at 600ft from holding spot 

Heli ‘W’, to the west of RW18 (see Figures 1 and 2). The FISO, who was providing a Basic Service 

to both aircraft, had an expectation that the helicopter would follow the standard helicopter circuit 

pattern centred on Heli ‘W’, operating inside and remaining segregated from the fixed-wing circuit 

(Figure 3). At the time of the Airprox the R44 was conducting a Proficiency Check, simulating an 

emergency. 

Figure 3 – position of the circuit patterns on the airfield 

The PA18 pilot had received approval from the Aerodrome Authority to operate on the grass strip 

for landings and take-offs provided that it was not used at the same time as the adjacent tarmac 

runway. 

Just prior to the Airprox the PA18 reported on final and the FISO advised the PA18 to, ‘land at 

your discretion on the grass’. The R44 pilot, who reported that she did not hear this RTF 

exchange, called final for aiming point Heli ‘W’ which the FISO acknowledged. The R44 had 

initiated a simulated emergency for an approach to the hover ¾ of the way along the grass that 

runs alongside the west of RW18. 

When questioned, the FISO was surprised to learn, subsequently, that the R44 pilot was not 

aware that the grass RWY was being used. The FISO was asked if perhaps the R44 had just 

joined the circuit and may have been unaware of the PA18. However the FISO, to the best of his 

knowledge, believed that both had been established in their segregated visual circuits and 

considered that they were aware of each other. 

The ATSU indicated that as a result of this Airprox, they have taken, or intend to take, the following 

action: 

a) The Airprox was discussed at an Airfield Safety meeting on 27 July 2013 and was 

subsequently discussed with the helicopter training school concerned in order to ensure that 

helicopter circuits are strictly adhered to. 

b) FISOs will be required to provide a warning when the grass strip is in use and this will be 

incorporated into the Wellesbourne FISO Manual. 

c) A review of the arrangements for grass strip operations will be completed and consideration 

given to an appropriate entry in the Wellesbourne Aerodrome and FISO Manuals together with 

a reference in the UK AIP regarding its restricted use. 

4

Summary 

The Airprox occurred within the Wellesbourne airfield ATZ, whilst both aircraft were receiving a BS 

from the FISO. The PA18 was carrying out right-hand circuits to the grass RW18. The R44 was 

operating in the right-hand helicopter circuit to Heli ‘W’. The helicopter circuit is designed to segregate 

it from the fixed-wing circuit and relies upon the helicopters following the published circuit pattern to 

Heli ‘W’. The R44 pilot was not aware that the PA18 was using the grass RWY when her helicopter 

was positioning to the grass area adjacent to RW18. This resulted in the R44 descending into close 

proximity to the landing PA18 which took avoiding action by commencing a left turn on the ground 

during which a ground loop ensued. The grass RW18 is not promulgated in the UK AIP. 


Information available included reports from the pilots of both aircraft involved, the FISO’s report, and 

a report from the appropriate ATC authority. 

The Board first considered the actions of the PA18 pilot and then the R44 pilot, both of whom were 

operating on the Wellesbourne FISO frequency. 

The PA18 was operating on a training flight to the grass RW18. The pilot was aware from the RTF 

that a helicopter was on final approach to Heli ‘W’ but, because the helicopter circuit and the fixedwing 

circuit are segregated at Wellesbourne, she expected the helicopter to be outside the ‘protected 

zone’ for fixed-wing traffic. However, approaching the grass runway threshold, she became aware 

that the helicopter had deviated from the helicopter circuit and was descending over the grass runway 

ahead of her PA18. A civil pilot member explained that from her seat in the back of the aircraft, 

because of the high wing, it would not have been possible to see the helicopter any sooner, whilst it 

was descending in her direction. Action was taken which resulted in a ‘ground-loop’ and the wing 

nearly touching the grass. 

Turning to the R44 pilot, at the time of the Airprox she was supervising a Proficiency Check in the 

helicopter circuit. In the view of several members, she had become absorbed in that task and was 

not sufficiently aware of the presence of the PA18, even though its pilot had reported on RTF that 

they were making a final approach to RW18 grass. They also found it most surprising, in view of her 

experience at the airfield, that she did not know of the presence of the grass runway. However, in her 

defence, the Board noted that, at the time of the Airprox, no reference was made to the grass runway 

in the Wellesbourne Aerodrome and FISO manuals, nor is there any reference on the relative page of 

the UK AIP entry for Wellesbourne. The Board considered that this lack of formal information was a 

key contributory factor in the occurrence. On approaching the airfield on this occasion, instead of 

positioning well to the west of the main RWY and routeing towards Heli ‘W’, in accordance with the 

helicopter circuit procedure, she allowed her candidate to approach towards the main RWY and, 

consequently, the grass RWY alongside, in the mistaken belief that her aircraft was the only one in 

the circuit pattern. Because neither she nor her candidate were aware of the presence of the PA18 

landing on the grass RWY (despite radio calls being made to that effect), the Board therefore 

considered that the cause of the Airprox was that the R44 crew flew into conflict with the PA18, which 

they did not see. 

The Board then considered the Category of risk. It was apparent that this was a very serious incident 

whereby, effectively, the PA18 pilot was presented with a situation where timely avoiding action was 

not possible. The fact that the PA18 pilot was able to swerve clear whilst on the grass was fortuitous, 

albeit nearly resulting in an accident in its own right. Some Board members thought that the action 

taken by the PA18 pilot had prevented the collision, albeit with safety margins much reduced below 

the normal. However, the majority felt that this was a far more serious incident, that an actual risk of 

collision had existed, that it had been avoided only by the very slimmest of margins and that nothing 

more could have been done to improve matters. It was agreed that an aircraft accident had only 

been narrowly avoided; therefore, it was decided that the risk Category should be A. 

5

Following this incident, the Wellesbourne ATS Unit took action to address formally the use and 

promulgation of the grass runway. The issue has been discussed at two Air Safety Committee 

meetings, which comprise representatives from the airfield users, to ensure that pilots are briefed 

appropriately. FISOs now provide, as suggested, warnings on the RTF when the grass RWY is in 

use; there are now also appropriate entries in the Wellesbourne Aerodrome and FISO Manuals. No 

decision has yet been made by Wellesbourne Mountford regarding whether there should be a 

reference to the grass runway in the UK AIP. However, because the Board assessed that the lack of 

entry about grass runway operations in the UK AIP was a contributory factor to this Airprox, it was 

considered that a recommendation should be made to Wellesbourne to review and update their AIP 

entry with respect to grass runway operations. 


Cause: 

Contributory factor: 

The R44 crew flew into conflict with the PA18, which they did not see. 

The Wellesbourne Mountford Aerodrome, FISO manuals and AIP entry did 

not include information with respect to grass runway operations. 

Risk: A. 



Wellesbourne Mountford review and update their AIP entry with respect to 





6


Date/Time: 23 Jun 2013 1235Z (Sunday) 

Position: 

5114N 00108E 

(10nm NNW DVR) 

Airspace: Lon CTA (Class: C) 

Reporting Ac 

Reported Ac 

Type: A330 Unknown 

Operator: CAT Unknown 

Alt/FL: FL225 NK 


and pilot report 

Not to Scale 

CPA 1235 

Reported Object 

Weather: VMC CLOC NK 

Visibility: 10nm NK 


80ft V/0ft H NK 


NK 

A330 

↑FL225↑ 

DVR 10nm 


THE A330 PILOT reports in the climb at 300kt, passing FL225. He was operating under IFR in VMC 

in CAS. The predominantly white aircraft had the SSR transponder selected on with Modes A, C and 

S. The aircraft was fitted with TCAS II. The pilot was operating under IFR, in receipt of a RCS from 

London LAS S. He saw a blue/black object ahead which passed just below them, based on a ‘very 

high relative speed’, less than 2 sec later. Based on the time from visual contact to CPA, he assessed 

that the object was not an aircraft, and had a volume of about 3m 3. He did not observe any TCAS 

alert, and ATC confirmed there was no other traffic within a 10nm radius. 

He assessed the risk of collision as ‘High’. 

THE LONDON CONTROLLER reports [the A330] was approaching DVR eastbound passing about 

FL200 when [the pilot reported] a bright blue object passed underneath the aircraft in close proximity. 

The pilot was unable to describe it further. The met wind at time was give as 280° at 30kt. 


CAA ATSI 

At 1235:30, an eastbound A330, climbing through FL228, reported to London Control that a 

foreign object had passed, “head on… just below”. The object was reported as blue in colour, of 

approximate size 3m 3 and not more than 1nm distant from the aircraft when first sighted. The 

A330 was 10.3nm west-northwest of DVR at the time of the report. Prevailing winds over Kent 

between FL200 and FL250 were recorded as westerly at 32-35kt. Extensive review of multiple 

surveillance sources did not detect any object in the vicinity of the A330 as reported. Additionally 

no other aircraft in the vicinity made similar reports. There were no notified meteorological or 

Radiosonde balloon releases in the area. 

1

NATS Ltd 

An Airprox with an object was reported by the pilot of [the A330]. Swanwick Safety was advised of 

the Airprox report 6 weeks after the event; however, the unit had filed an observation on the 

encounter at the time of the event. 

At 12:35:25, 23 rd of June 2013, the aircraft was under the control of the LAC DVR sector, passing 

FL225 when the pilot made the following report: 

A330 “London [A330 C/S]” 

LAC “Pass your Message” 

A330 “We just ah, we just um, foreign object, unable to identify. It was head on, it went just below us, on 

our current track. We’re passing now Flight level two two eight.” 

LAC “Ah [A330 C/S], thank you, so what kind of size was it?” 

A330 “Well, it looked blue and it didn’t look like an airplane, I have no idea what it was.” 

LAC “[A330 C/S], okay, thanks for your information, there are no… there are no aircraft in your vicinity 

for about ten miles actually and I can see no unusual primary returns in your area.” 

A330 “Roger.” 

Upon receipt of the traffic information from the A330 pilot the controller passed a warning to an 

aircraft following the approximate profile of the A330 (see Figure 1 below). The trail pilot 

acknowledged the warning but did not report a sighting of the object reported by the A330 pilot. 

Figure 1 

The investigation reviewed data from all radars capable of scanning the area around [A330 C/S] 

at the time of the reported event. There were no returns visible that correlated with the pilot report. 

Given the reported size of the object, if it had been of a significant mass, it would normally be 

expected to have produced a radar return given that NATS Ltd radars are calibrated to show 

objects with a radar reflecting cross-section of 1 square metre. 

An Airprox was reported by the A330 pilot after the crew observed an object, which they 

perceived not to be an aircraft, in close proximity. There were no radar returns correlating with the 

reported object in the vicinity at the time of the event and no other supporting report from an 

aircraft following a similar flight profile and route behind the A330. 

2

Summary 

An Airprox was reported by an A330 pilot after an encounter with an object, reported as not being an 

aircraft, in the DVR area. The investigation has not been able to identify the reported object. 


Information available included a report from the A330 pilot, a transcript of the relevant RT frequency, 

radar video recordings, reports from the air traffic controllers involved and reports from the 

appropriate ATC authorities. 

Members discussed the possible nature of the object as perceived by the A330 crew and, in their 

experience, it was felt that it may have been a toy balloon or similar. However, after some discussion 

it was decided that the dearth of information available regrettably rendered any meaningful finding 

impossible. 


Cause: 

Sighting report. 

Degree of Risk: D. 

ERC Score 1 : 

N/S 




3


Date/Time: 1 Aug 2013 1133Z 

Position: 

5309N 00219W 

(1nm S Arclid Airfield 


Airspace: London FIR (Class: G) 

Reporting Ac 

Reported Ac 

Type: EV-97 Mooney M20 

Operator: Civ Trg Civ Pte 


QNH (1008hPa) 




100ft V/100m H 


100ft V

The Rules of the Air 2007, Rule 11 states that: 

(1) ...an aircraft which is being overtaken in the air shall have the right-of-way and the overtaking 

aircraft, whether climbing, descending or in horizontal flight, shall keep out of the way of the other 

aircraft by altering course to the right. 

(2) An aircraft which is overtaking another aircraft shall keep out of the way of the other aircraft 

until that other aircraft has been passed and is clear, notwithstanding any change in the relative 

positions of the two aircraft”. 

The Manchester METAR 1120 was: 

18010KT 150V220 9999 FEW 018 SCT 028 24/18 Q1008 NO SIG= 


Information available included a report from one of the pilots involved and a radar video recording. 

The Board were disappointed that the pilot of the Mooney M20 had not responded to several 

requests to complete an Airprox report. Consequently, it was not possible to determine whether he 

had ever obtained visual contact with the EV97. However, in view of the weather conditions reported 

by the EV97 pilot (CAVOK) there was no reason, from a weather perspective, that he should not have 

been able to see the other aircraft. 

The Board were mindful of the fact that the sole objective of the UKAB is to assess reported Airprox 

in the interests of enhancing flight safety; it is not the purpose of the Board to apportion blame or 

liability even if one pilot chooses not to participate in the process. Although both pilots were equally 

responsible for collision avoidance in Class G airspace (Rule 8), lacking any further evidence from 

the Mooney pilot, the Board concluded that the M20, being faster than the EV97, was overtaking the 

latter aircraft at the time of the Airprox. Therefore, they opined that the M20 pilot had every 

opportunity to see the EV-97 and should simply have kept out of its way (Rule 11). As a result of this 

the Board decided that the cause of the Airprox was that the M20 pilot flew close enough to the EV97 

to cause its pilot concern. 

Once the cause had been determined, considerable discussion then took place about whether the 

risk should be classified as a Category B, C or D. Members decided that, although there was no 

report from the M20 pilot, and so they could not ascertain what he had or had not seen, there was still 

sufficient evidence from the radar recordings and the EV97 pilot’s report to render a meaningful 

finding. If the M20 pilot had not seen the EV-97 then safety margins had been much reduced 

because the two aircraft had come within 100ft vertically and < 0.1nm. If the M20 pilot had seen the 

EV-97 then he had flown too close and had disregarded the requirement to pass by on the right of the 

EV-97, thereby also reducing safety margins below normal. Therefore, in either case, the Board 

decided that the M20 had passed sufficiently close to the EV97 (recorded as 100ft V and



Position: 

Airspace: 

5126N 00001E 

(4.7nm SSW London/City Airport) 

London/City CTA (Class: D/G) 

Lon FIR 

Reporting Ac 

Reported Ac 

Type: Avro RJ1H Robin DR400 

Operator: CAT Civ Pte 


QNH (NK hPa) QNH (NK hPa) 

Weather: VMC CAVOK VMC CLNC 

Visibility: NK >10km 



100ft V/0.5nm H NK 

600ft V/0.6nm H 

CPA 1217:31 

600ft V/0.6nm H 

A16 

A14 

A14 

A15 

DR400 


A20 

A14 

NM 

0 1 2 3 

A21 

17:19 

17:07 

A23 

16:55 

A25 

1216:43 

A26 

RJ100 


THE RJ1H PILOT reports conducting an approach to London/City airport (LCY). The white and red 

aircraft had SSR transponder selected on with Modes A, C and S; the aircraft was fitted with TCAS II. 

The pilot was operating under IFR in VMC with a Radar Control Service from Thames RAD. Whilst 

downwind for RW09 ILS, 7-8nm south of LCY, heading 280°, at 190kt, and just levelling off at altitude 

2000ft, he received a TCAS TA from ‘a small VFR traffic about 700ft below and 0.5nm away’ in his 10 

o’clock position. He saw the traffic and identified it as a ‘PA28 type’, low-wing, single-engine lightaircraft. 

Shortly after, a TCAS RA ‘Monitor Vertical Speed’ was triggered, indicating a ROD of not 

more than 0fpm. The aircraft autopilot was already levelling off, ‘ALT Captured’ at 2000ft, with a ROD 

of 300ft decreasing to zero. After the Intruder passed their 9 o’clock position the TCAS advised ‘Clear 

of Conflict’. He informed Thames RAD of the RA and continued the approach into LCY. A second 

TCAS TA occurred on final for RW09 at about 7nm caused by traffic about 500ft below. He stated 

that the TCAS RA had occurred at a busy point in the flight as they were preparing to configure the 

aircraft for landing. 


THE DR400 PILOT reports transiting through the LCY ‘zone’. The red and white aircraft had strobes 

selected on, as was the SSR transponder with Modes A, C and S. The aircraft was fitted with a Traffic 

Advisory System (TAS). The pilot was operating under VFR in VMC and reported being in receipt of a 

‘Radar Service’ from Heathrow RAD 1 . He was tracking around the Heathrow CTR, planning to transit 

to the north-north-east. He obtained a crossing clearance from Heathrow and, after being instructed 

to descend from 2000ft to 1500ft in a right-hand orbit, was given clearance by the radar controller to 

transit the ‘City zone’, initially taking up a heading of 060° at 120kt. He neither saw nor heard a 

conflict, he was not advised of a conflict by the controller, and his TAS did not generate a warning. He 

was unaware of an Airprox until advised by the Radar Analysis Cell. 

He assessed the risk of collision as ‘None’. 

1 He was in receipt of a Basic Service at the time of the Airprox.

THE THAMES RAD CONTROLLER did not file a report. A transcript of the RTF is reproduced below; 

RT which was not relevant to the incident has not been included: 

From To Transcribed Speech Time 

RJ1H RAD Thames good day [RJ1H C/S] R J one hotel, information Xray, er we're out of six thousand descending 

four thousand on course to Detling 

1208:10 

RAD RJ1H [RJ1H C/S] Thames roger fly heading three zero five vectors runway zero nine 

RJ1H RAD flying heading three zero five for vectors runway zero nine [RJ1H C/S] 

RAD RJ1H [RJ1H C/S] reduce speed to two ten knots 1209:20 

RJ1H RAD reducing two ten [RJ1H C/S] 

RAD RJ1H [RJ1H C/S] reduce to one niner zero knots 1210:00 

RJ1H RAD one ninety [RJ1H C/S] 

RJ1H RAD and [RJ1H C/S] request one ninety five to Detling 

RAD RJ1H roger that's all approved 

RJ1H RAD -kay 

RAD RJ1H [RJ1H C/S] descend altitude three thousand feet, Q N H one zero one four at City airport 

RJ1H RAD descend three thousand feet Q N H one zero one four [RJ1H C/S] 

RAD RJ1H [RJ1H C/S] delaying action, turn right heading three six zero degrees 

RJ1H RAD right heading three six zero [RJ1H C/S] 1211:00 

RAD RJ1H [RJ1H C/S] turn left heading two six zero degrees 

RJ1H RAD left heading two six zero [RJ1H C/S] 1212:00 

RAD RJ1H [RJ1H C/S] turn left left heading one eight zero degrees 

RJ1H RAD left heading one eight zero [RJ1H C/S] 1213:00 

RAD RJ1H [RJ1H C/S] turn right heading two eight five 

RJ1H RAD right heading two eight five [RJ1H C/S] 1214:00 

RAD RJ1H [RJ1H C/S] turn right heading two nine zero degrees 

RJ1H RAD heading two nine zero [RJ1H C/S] 

RAD RJ1H [RJ1H C/S] descend altitude two thousand feet 1216:00 

RJ1H RAD [unreadable] two thousand feet [RJ1H C/S] 

RAD RJ1H [RJ1H C/S] helicopter traffic left nine o'clock range of one mile will pass behind at fourteen hundred feet 1217:20 

RJ1H RAD roger 

RAD RJ1H [RJ1H C/S] reduce speed to one six zero knots until five D M E, turn left heading two eight zero degrees 

RJ1H RAD reducing to one sixty, left heading two eight zero degrees and we had er traffic R A [RJ1H C/S] 

RAD RJ1H roger 

RJ1H RAD and [RJ1H C/S] confirm heading two eight zero 1218:00


RAD RJ1H two eight zero degrees sir affirm speed one sixty knots 

RJ1H RAD okay 

THE HEATHROW RAD CONTROLLER did not file a report. A transcript of the RTF is reproduced 

below; RT which was not relevant to the incident has not been included: 


DR400 RAD Heathrow radar good morning good afternoon indeed er [DR400 C/S] 1213:00 

RAD DR400 [DR400 C/S] Heathrow radar squawk seven zero three four, pass your message 

DR400 RAD seven zero three four standby 

DR400 RAD er [DR400 C/S] a robin D R four hundred [departure aerodrome] to a private strip [north-east of 

Stansted], we're just at er just passed Mitcham on the eastern edge of your zone, two thousand feet 

one zero one three, we would like transit through the er city zone if approved at this height please 

and er we're happy with a er basic service 

RAD DR400 [DR400 C/S] roger it's a basic service outside controlled airspace, the Q N H one zero one three, I’ll 

call you back 

1214:00 

DR400 RAD one zero one three and a basic outside controlled airspace, standing by [DR400 C/S] 

RAD DR400 [DR400 C/S] I’ll be unable to er approve a direct transit at that altitude, would you be able to 

descend 

DR400 RAD affirm [DR400 C/S] 

RAD DR400 [DR400 C/S] the traffic you may see just in your left eleven o'clock is inbound to London City at the 

same level but he's inside controlled airspace 2 1215:00 

DR400 RAD yep we're visual with him er what height would you like me to descend to 

RAD DR400 i- i- the clearance will be not above fifteen hundred feet V F R, if you could just make an orbit there 

until you're level please I won't be able to clear you in until you're level due the London City 

downwind traffic 

DR400 RAD orbiting er right in order to descend to fifteen hundred feet [DR400 C/S] 

RAD DR400 [DR400 C/S] when you've completed that orbit you're cleared to enter the London City control zone 

V F R towards the southern tip of the isle of dogs and then it'll be a transit up the lee valley when 

cleared on, are you familiar with that routeing 

1216:00 

DR400 RAD erm not entirely but er I am er good V F R 

RAD DR400 [DR400 C/S] roger what was gonna be your ideal transit track then 

DR400 RAD erm erm er abeam er lima charlle yankee would be nice 

RAD DR400 okay er [DR400 C/S] roger then then you'll clearance will be V F R not above fifteen hundred feet, 

your clearance limit will be the Thames Barrier on the south side of London City 

DR400 RAD roger er understand er not further in than the Thames Barrier but in fact we will further to the east of 

that er, orbit completed and er clear to enter I understand 

2 The subject RJ1H was in the DR400 pilot’s right 1.30 at 11nm at this time.


RAD DR400 affirm traffic though just as you roll out of that orbit will be in around about your twelve o'clock two 

miles descending to two thousand feet inbound to London City 

1217:00 

DR400 RAD visual with that aircraft [DR400 C/S] 

RAD DR400 [DR400 C/S] roger your clearance limit is the Thames Barrier so no further north that the Thames 

Barrier until cleared 

DR400 RAD that's copied [DR400 C/S] thank you 1217:20 

[no further transmissions until after CPA] 


The LCY weather was recorded as follows: 

METAR EGLC 231150Z 08009KT 9999 -SHRA FEW022 24/19 Q1014 RERA 

METAR EGLC 231220Z 08010KT 9999 FEW024 25/18 Q1014 


CAA ATSI 

The RJ1H pilot was operating under IFR to London City, and was in receipt of a Radar Control 

Service from Thames RAD. The DR400 pilot was operating under VFR from Fairoaks to a private 

site to the north-east of Stansted and was in receipt of a Basic Service from Heathrow TC SVFR 

(Heathrow RAD). 

CAA ATSI had access to written reports from both pilots, area radar recordings, RTF recordings 

and transcripts of the Thames RAD and Heathrow RAD frequencies. 

At 1213:40, the DR400 pilot contacted Heathrow RAD at 2000ft, requesting a transit through the 

City Zone and a Basic Service. A Basic Service was agreed. The DR400 pilot was informed that a 

direct transit at that level was not available and the pilot was asked if he could descend. He 

replied that he could and was instructed to descend to 1500ft, remaining outside CAS. The 

Heathrow RAD co-ordinated the DR400 with Thames RAD and a clearance to transit VFR not 

above 1500ft towards the Thames Barrier VRP was subsequently issued to the DR400 pilot. 

At 1216:51, low level Short Term Conflict Alert (STCA) activated. At 1217:00, the DR400 pilot was 

passed traffic information on the RJ1H, in his 12 o’clock at 2nm, descending to 2000ft inbound to 

London City (see Figure 1). The DR400 pilot reported visual with the RJ1H and STCA deactivated 

at 1217:03.

Figure 1: DR400 squawk 7034, RJ1H squawk 5722 

The Thames RAD gave a closing heading for the ILS to another aircraft. During this interchange, 

low level STCA activated again and immediately afterwards, at 1217:29, the Thames RAD passed 

traffic information on the DR400 to the RJ1H pilot, stating that the traffic was “helicopter traffic left 

nine o’clock range of one mile will pass behind at fourteen hundred feet” (see Figure 2). 

Figure 2: DR400 squawk 7034, RJ1H squawk 5722 

When the incident occurred, the RJ1H was at 2000ft in class D airspace while the DR400 was 

outside CAS, with a clearance to enter not above 1500ft. No separation minima are prescribed 

between IFR and VFR traffic in Class D airspace, however, traffic information must be passed on 

VFR traffic to IFR traffic and traffic avoidance given if requested. The RJ1H pilot was passed 

traffic information on the DR400 who had reported the RJ1H in sight. Traffic information was also 

passed on the DR400 to the RJ1H pilot prior to the DR400 entering the Class D airspace. Earlier 

traffic information may have improved the RJ1H crew’s situational awareness, however, it is likely 

that the Thames RAD’s workload precluded this. 

Summary 

An Avro RJ1H and Robin DR400 flew into proximity on the edge of the LCY CTA at 1217 on 23 rd July 

2013. Traffic information on each aircraft was passed to both pilots; the RJ1H pilot subsequently 

received a TCAS RA ‘Monitor Vertical Speed’.


Information available included reports from the pilots of both ac, transcripts of the relevant RT 

frequencies, radar photographs/video recordings and a report from the appropriate ATC authority. 

Members first considered the pilots’ actions. The RJ1H pilot was operating under IFR in Class D 

airspace within the London/City CTA; the DR400 pilot was operating under VFR in Class G airspace 

below the London/City CTA. Both were operating in compliance with their respective clearances, 

were in 2-way RT contact with different controllers and each was passed Traffic Information on the 

other aircraft. The RJ1H pilot stated that he saw the DR400 indicate on TCAS and then saw it 

visually, presumably after he was cued by the TCAS display. The DR400 pilot was visual with the 

subject RJ1H (as noted from the Heathrow RAD transcript) and commented in his narrative about not 

seeing any conflicting aircraft. Members noted that the RJ1H pilot had received a TCAS RA ‘Monitor 

Vertical Speed’ as he was levelling off at his cleared altitude of 2000ft, which required him not to 

descend. 

Turning to the controllers, the 2 aircraft had been coordinated with 500ft separation and the required 

clearances had been issued. The controllers were required to give traffic information between IFR 

and VFR traffic, which they did. 

The Board then discussed in detail the issue of TCAS RAs in mixed IFR/SVFR/VFR circumstances, 

including at the boundaries of controlled and uncontrolled airspace. The discussion also considered 

the assumption by some that an RA was, by definition, an Airprox. Some members were of the 

opinion that an RA should be considered contextually, especially as TCAS is not optimised for the 

CTR environment. Broadly speaking, RAs could be considered in 2 classes, those that caused the 

aircraft to deviate from its planned flight path, either through manual or automatic intervention 

(manoeuvre RAs), and those that did not (monitor RAs). In the former case, e.g. ‘Climb Climb’, it 

could reasonably be assumed that the system was changing aircraft flight paths in order to prevent 

collision or, at the very least, close proximity. In the latter, it could be argued that the aircraft were 

always going to pass well clear of each other and that the system was simply advising the pilot to 

remain on the selected flight path in order to maintain already safe separation. It was noted that 

TCAS II Version 7.1 defines the ‘Monitor Vertical Speed’ RA as a ‘Preventive RA’, i.e. the RA is 

preventing collision by maintaining an already safe separation. The Board recognised that there were 

many facets to TCAS design, that their broad definition could not cover all cases, and that the pilot’s 

primary and only concern was to follow the instructions generated by the RA, whatever they were. 

However, the generation of an RA did not necessarily imply that an Airprox had occurred; it was felt 

that the considerations above could usefully be used by pilots when subsequently considering the 

level of risk in their event, and whether an Airprox report was justified. 

Considering the cause and risk for this Airprox, the Board felt that normal procedures, safety 

standards and parameters had pertained. However, notwithstanding the Board’s discussion and 

findings, it was also felt that it was highly undesirable for pilots of TCAS equipped aircraft to receive 

TCAS RAs of any kind, and that their occurrence should never be considered normal. Considering 

the circumstances of this and similar occurrences covered in other Airprox reports 3 , the Board agreed 

to recommend that the CAA review VFR/SVFR traffic procedures within CAS with respect to 

interaction with TCAS equipped aircraft and, specifically, RA occurrences. 

3 e.g. 2013099 and 2013121.


Cause: 


Degree of Risk: E. 



The CAA reviews VFR/SVFR traffic procedures within CAS with respect to 

RA occurrences in TCAS equipped aircraft. 



assessment of ERC.


Date/Time: 4 Aug 2013 1141Z (Sunday) 

Position: 

5219N 00014W 

(Huntingdon) 


Reporting Ac 

Type: ASH 26 C182 

Reported Ac 

Operator: Civ Pte Civ Pte 


QNH (NK hPa) QNH (1019hPa) 

Weather: VMC CLBC VMC CLBC 

Visibility: >50km 10km 




The Cambridge weather was recorded as follows: 

METAR EGSC 051120Z 17012KT 140V220 9999 FEW035 23/13 Q1011 



Both pilots were equally responsible for collision avoidance 2 and the C182 pilot was required to 

give way 3 . The C182 pilot turned steeply to his right to avoid the glider; the glider pilot also took 

avoiding action by diving steeply to his right. 

Summary 

An ASH 26 glider and a C182 flew in to conflict in Class G airspace, 1nm south-west of Huntingdon, 

at 1141 on 4 th August 2013. Neither pilot was in receipt of an ATS; the pilots saw each other and 

each took avoiding action. 


Information available included reports from the pilots of both ac, radar video recordings and a GPS 

track log. 

The Board first considered the C182 pilot’s actions and his reported initial sighting of the glider at a 

distance of 1.5-2nm. Correlating his comment about seeing the glider first when it was on a southerly 

heading to the glider pilot’s GPS track log, it was felt that the C182 pilot had probably first seen the 

glider about 150° into the glider’s first right turn, and at the much closer range of about 1/3nm. At the 

C182 pilot’s reported speed of 120kt, this would have reduced the time to CPA to about 10sec. 

Members noted that it was often difficult to gain and maintain visual contact with gliders, and it was 

also sometimes hard to determine their attitude and aspect; the C182 pilot was therefore right to be 

concerned that a change to his flight path might have exacerbated the situation. Nevertheless, in the 

event, he was the one who was required to give way and members felt that, on first sighting the 

glider, a change in altitude and a positive turn would have increased the miss-distance without 

significantly increasing risk. In his case, sitting on the left-hand side of a high-wing aircraft, a climb 

and turn to the right would have been of benefit, whilst also allowing him to then subsequently look 

into the area he had first seen the glider, giving the best chance of maintaining visual contact. 

The ASH 26 pilot saw the C182 only as it was crossing his nose; some members opined that the 

sighting would probably have been too late to have had any effect in avoiding the collision if the C182 

had been closer. 

Finally, members noted that mitigation against midair collision in Class G airspace was ultimately 

based on pilots looking out, seeing other traffic and manoeuvring appropriately to avoid; early action 

to resolve conflictions was essential and should not be delayed until the last minute. Very often, a 

climb will be the best course of action for a powered aircraft when approaching a co-altitude glider. 

The Board opined that the Airprox was caused by the late sighting by both pilots; they spent some 

time discussing the risk. Ultimately, it was decided by a majority that, although avoiding action was 

taken by both pilots, safety margins had been much reduced below normal. 


3 ibid. Rule 9 (Converging). 

2


Cause: 

A late sighting by both pilots. 

Degree of Risk: B. 





3



Position: 

5130N 00011W 

(6nm West London City airport 


Airspace: London City CTR (Class: D) 

Reporting Ac 

Type: RJ1H R44 

Reported Ac 

Operator: CAT Civ Pte 


QNH (1008hPa) QNH 

Weather: VMC CAVOK VMC CLBC 

Visibility: >10km >10km 



500ft V/400-500m H 

500ft V/0.4nm H 

NK 

CPA 1211:50 

500ft V/0.4nm H 

Heathrow 

E’ly CTR Boundary 

11:38 

11:26 

A109 

1500ft alt 

11:14 

11:02 

1210:50 


RJ1H 

2000ft alt 

LCY RW09 C/L 

3 

2 

1 

0 

NM 


THE RJ1H PILOT reports inbound, IFR, to London City airport (LCY). All lights were illuminated and 

SSR Modes C and S were selected, squawking 5725. During approach to RW09, on an ILS intercept 

heading 060° at 2000ft, City Radar informed him about “a couple” of helicopters at about the 1 o’clock 

position. He had visual contact and received a TCAS TA. A few seconds later a TCAS RA ‘monitor 

VS’ was received. Since he had the helicopters clearly identified and he was flying above VS red 

indication on TCAS, he continued the approach. About ten seconds later ’clear of conflict’ was 

received. He reported having received a TCAS RA to ATC, after the aircraft had landed. 


THE ROBINSON R44 HELICOPTER PILOT reports operating on a VFR flight under the control of 

Heathrow radar 125.625MHz. The helicopter, coloured predominately blue, had a strobe and 

navigation lights illuminated. SSR Mode C was selected. ACAS was not carried. He was conducting 

an aerial filming task approximately 6nm West of LCY. He was flying in accordance with his ATC 

clearance under a Radar Control service to operate on Helicopter Route H4, with a limit of no further 

East than London Bridge and no further West than Vauxhall Bridge. At times, he had clearance to 

operate off-route in the region of Trafalgar Square. His altitude clearance was not above 1500ft on 

the London QNH. He complied fully with his given clearance and at no time did he exceed any of the 

geographical limits. He did not believe he had exceeded any of the vertical limits of his clearance. He 

was given regular traffic information on other helicopters operating on H4, as well as the inbound 

aircraft to LCY. Either through his own visual scan or regular traffic information, he remained in visual 

contact with the arriving aircraft as well as other traffic in his operating area. 



MATS PART 1 1 states: ‘Separation standards are not prescribed for application by ATC between VFR 

and IFR flights in Class D airspace’. 

1 MATS Part 1, Chapter 5, Paragraph 5.3 

1

MATS Part 1 2 states the ATC responsibilities for Class D airspace: ‘....Pass traffic information to IFR 

flights on VFR flights and give traffic avoidance if requested; Pass traffic information to VFR flights on 

IFR flights and other VFR flights’. 

The London City weather was: 

EGLC 011150Z 14010KT 100V180 CAVOK 30/18 Q1009= 

EGLC 011220Z 15010KT120V210 CAVOK 31/18 Q1008= 


CAA ATSI 

An Airprox was reported by a British Aerospace RJ100 (RJ1H) following receipt of a TCAS RA 

against a Robinson R44 II (R44) in Class D airspace, whilst being vectored for the ILS approach 

to RW09 at London City. CAA ATSI had access to written reports from both pilots, area radar 

recordings, RTF recordings of the TC SVFR frequency and recordings and transcripts of the City 

Radar frequency and the London City Tower frequency. No reports were received from either the 

TC City Radar or SVFR controllers. 

The RJ1H was operating IFR inbound to London City, squawking 5725, and was in receipt of a 

Radar Control Service from City Radar on frequency 128.025MHz. 

The R44 was operating VFR, squawking 7032, and was in receipt of a Radar Control Service 

from TC SVFR on frequency 125.625MHz. 

At 1210:45, having instructed the RJ1H to turn right heading 015°, the City Radar controller 

passed traffic information to the RJ1H about helicopters operating under 6nm final with the 

highest one [the R44] at 1500ft, visual with the RJ1H (Figure 1). The RJ1H pilot replied he was 

looking. 

Figure 1 

Meanwhile, at 1210:56, the TC SVFR controller passed traffic information on the RJ1H to the R44 

pilot, who replied that he was visual with the RJ1H. 

At 1211:20 the City Radar controller updated the traffic information to the RJ1H, stating that the 

first helicopter was in its half past twelve at one and a half miles at 1500ft and would pass down 

the RJ1H’s right hand side (Figure 2). The RJ1H pilot reported that he had the helicopter in sight 

and was subsequently vectored for the ILS to land at LCY. 

2 MATS Part 1, Section 1, Chapter 2, Page 2 

2

Figure 2 

At 1216:00, after landing at LCY, the RJ1H pilot informed the LCY Tower controller that they had 

received a TCAS RA because of the helicopters, and they were required to report it in 

accordance with company policy. 

Summary 

The Airprox occurred within Class D airspace of the London City CTR. The RJ1H was operating IFR 

and the R44 VFR. Both the City and SVFR radar controllers complied with ATC responsibilities for 

flights within Class D airspace; appropriate traffic information was issued to both flights. Both pilots 

obtained visual contact with the other aircraft. The closest point of approach was 0.4nm as the aircraft 

passed each other, vertically separated by 500ft. The RJ1H received a TCAS RA but neither pilot 

considered there was any risk of collision. 


Information available included reports from the pilots of both aircraft, area radar recordings, 

transcripts of the relevant RT frequencies and reports from the appropriate ATC and operating 

authorities. 

Before considering the Airprox itself, Board members commented that a number of similar Airprox 

reports had been filed by pilots of the operator of this RJ1H. All bar one involved aircraft inbound to 

RW09 at LCY receiving TCAS RAs concerning VFR aircraft 500-600ft below them in, or close to, the 

LCY CTR. It transpired that the associated airline’s company mandatory occurrence reporting form 

automatically links the reporting of TCAS RAs to the reporting of Airprox. 

The Board then considered the actions of the pilots on this occasion. The R44 had been carrying out 

a filming task, VFR, under the control of TC SVFR. At the time of the Airprox it was complying with 

ATC instructions and was heading south, within the LCY CTR, to pass 6nm west of the airport at 

1500ft. The Board noted that the R44 pilot had been informed about the RJ1H heading north at 

2000ft, and reported visual contact. For his part, the RJ1H, inbound IFR to LCY, was routeing 

northbound on a reciprocal track to the R44 at 2000ft. ATC informed the RJ1H pilot about the R44, 

which had him in sight, and the RJ1H pilot visually observed the R44 before subsequently receiving a 

TCAS RA because of its presence. The Board noted that the RJ1H pilot did not alter his flight profile 

as a result of the TCAS alert because the associated RA instruction was simply to monitor vertical 

speed - level flight was within the required parameters. An airline pilot member confirmed that, as in 

other similar events, this was appropriate action to take in the circumstances. 

Finally, with respect to ATC, the Board considered that the TC City/Thames Radar and SVFR 

controllers had both complied with their overall responsibilities and had passed appropriate traffic 

information to both flights which were conducted under normal procedures and separation standards 

3

for the airspace involved. In the event, 500ft vertical and 0.4nm horizontal separation had been 

achieved even though there was no specific requirement so to do. 

The Board members agreed that the Airprox had been reported because of the TCAS RA received by 

the RJ1H due to the R44’s flight vector. They unanimously agreed that this was a TCAS sighting 

report. In view of recent similar Airprox being assessed as a Category E (normal procedures, safety 

standards, and parameters pertained) it was decided that this Airprox should also be similarly 

categorised . However, irrespective of the benign circumstances surrounding this particular event, 

the Board were concerned that it should not be considered normal procedure for aircraft being 

vectored within the LCY CTR to receive TCAS RAs lest pilots become inured to what might become 

normalised routine behaviour rather than reacting fully to TCAS alerts. A number of members also 

commented that this type of occurrence could easily occur at other airports within Controlled Airspace 

and should not be considered unique to LCY, especially with the potential increase in Class D 

airspace that might be introduced at other regional airports in future. Therefore, in conjunction with 

Airprox 2013095 and 2013121 (also assessed during this Board), they decided to generate an 

overarching recommendation that the CAA reviews VFR/SVFR traffic procedures within CAS with 

respect to RA occurrences in TCAS-equipped aircraft. 


Cause: 

Degree of Risk: 


E 








4





Position: 

5405N 00123W 

(5nm WNW Linton) 

Airspace: Vale of York AIAA (Class: G) 

Reporting Ac 

Type: Tucano T1 Glider 

Reported Ac 

Untraced 

glider 

Operator: HQ Air (Trg) Unknown 

Alt/FL: FL40 NK 

CPA 




NM 

2 

1 

01:31 A42 

01:19 A39 

01:07 A35 

00:55 A32 

00:43 A28 

300ft V/0ft H 


NK 

NK 

0 

1500:31 A24 

Tucanos 


THE TUCANO PILOT reports leading a 2-aircraft close-formation departure from RAF Linton-on- 

Ouse (LIN). The black and yellow aircraft had navigation lights and HISLs selected on, as was the 

lead aircraft’s SSR transponder with Modes A and C. The aircraft was fitted with TCAS I. He was 

operating under VFR in VMC and in receipt of a Traffic Service from the LIN Departure Controller 

(DEP), with ‘Glider Ops’ in force 1 . Upon receipt of this service he was immediately informed of three 

primary radar contacts; two to the south-west of his position and one to the north-west. Determining 

that the later, being ‘on his nose’, was a greater threat, he asked for an update on its position. He 

reported being told 'north-east, 1nm, no height', at which point he turned right to try and achieve 

deconfliction. Shortly after turning, heading 300° at 150kt and climbing through FL40, his wingman 

became visual with glider traffic as it passed directly beneath them with an estimated vertical 

separation of 200-300ft. He stated that the glider was at around 4000ft, 4nm west of LIN, and that 

despite having the radar service and directing all of his spare attention towards lookout, he never 

achieved visual contact with the glider. He noted that a gliding competition had launched that 

afternoon from Sutton Bank (hence the 'Glider Ops' decision) and that the task route was largely 

orientated north-south, with the legs repeatedly crossing the ‘Vale of York MATZs’. He stated that he 

was concerned that despite taking every reasonable step to try and gain visual contact with the glider, 

he was still unable to do so. 


THE GLIDER PILOT: Despite extensive tracing action, the glider pilot could not be located. 

THE LIN DEP CONTROLLER reports that he was unaware of the incident at the time it happened 

and was submitting his report as a response to the hazard observation that was submitted. A VFR 

departure clearance was given to the Tucano formation to take-off during ‘Glider Ops’ at LIN. The 

subject Tucano pilot spoke with LIN DEP about 5min later. He climbed out, requested a Traffic 

Service and was identified and given traffic information on 3 non-squawking contacts west and northwest 

of the airfield all at a range of about 4-5nm with no height information available. As the Tucano 

pilot continued his departure profile, updated traffic information was passed as he got closer to a PSR 

contact. The Tucano passed the traffic before going en-route within a few minutes. 

1 During which there is a mandatory requirement of at least a Traffic Service whilst on departure, until the aircraft is in an 

operating area clear of significant glider activity. 

1

THE LIN SUPERVISOR reports he was not aware an Airprox had been reported and had no 

recollection of events surrounding this incident. 

A LIN CONTROLLER reports that the incident was not reported on RT at the time, or by any means 

afterwards. The incident was originally submitted as a ‘Hazard Observation’ and subsequently 

‘upgraded to an Airprox’. The ATC DASOR 2 was consequently not submitted by the LIN DEP until 

one week after the event. This highlighted the importance of aircrew reporting any possible incident 

as soon as possible to ATC so that the investigation process could occur as soon as possible after 

the event such that events were fresh in the memory of the controllers/personnel involved. 


The LIN weather was recorded as follows: 

METAR EGXU 021450Z 17011KT 9999 FEW020CB FEW030TCU 24/16 Q1004 BLU NOSIG 


Military ATM 

This incident occurred 4.9nm WNW of LIN, at 1501:33 on 2 Aug 13, between a formation of 2 

Tucanos and a glider. The Tucano Formation were departing LIN on a VFR departure and were 

in receipt of a TS from LIN DEP. The RAC were unable to trace the glider involved. All 

heights/altitudes quoted are based upon SSR Mode C from the radar replay unless otherwise 

stated. 

The incident was initially reported as a ‘hazard observation’ on 6 Aug 13 and upgraded to an 

Airprox on 7 Aug 13. The incident was not reported on the RTF in use and LIN ATC were not 

advised of the incident until around 9 Aug 13; thus the personnel involved had little recollection of 

events. The Tucano Formation leader reported that a ‘gliding competition had launched that 

afternoon from Sutton Bank and that the task route was largely orientated North-South, with the 

legs repeatedly crossing the ‘Vale of York MATZs’. This promulgated competition prompted LIN 

to implement their ‘Glider Ops’ procedure. 

LIN Flying Order Book states that ‘On days when significant amounts of glider activity are planned 

or observed, the DSS may invoke the ‘Glider Ops Departure and Recovery Procedure’. This 

procedure may be directed because of planned glider activity, such as a competition, or because 

of activity noted on radar or seen by aircrew or air traffic personnel’. The procedure details a 

number of specific actions for aircrew and ATC, including ‘The mandatory use of at least a Traffic 

Service whilst on departure, until the aircraft is in an operating area clear of significant glider 

activity’. 

The Tucano Formation got airborne at around 1459:30, making initial RT contact with LIN DEP at 

1459:52, “passing 1300 ft, request Traffic Service.” The Tucano Formation were identified and 

placed under a Traffic Service. DEP then immediately passed TI to an unrelated Tucano that had 

got airborne immediately ahead of the Tucano Formation; this exchange ran from 1500:05 to 

1500:19. 

Between 1500:20 and 1500:22, there was a brief transmission and acknowledgement within the 

Tucano Formation, followed, at 1500:23, by DEP passing them TI on “2 tracks, south-west, 

manoeuvring between 3 and 4 miles, no height information, believed to be gliders” which was 

acknowledged. Immediately, DEP then advised the Tucano Formation of “further traffic, northwest, 

4 miles, tracking south, no height information, believed to be another glider” which was also 

acknowledged. Although no primary contact was displayed on the radar replay at this time, one 

2 Defence Aviation Safety Occurrence Report. 

2

subsequently became visible at 1501:01, on the Tucano Formation’s projected track. Figure 1 

depicts the Tucano Formation’s 

position at 1500:23 (highlighted SSR 

3A 4577), with a range and bearing 

line attached to the position of 2 

primary contacts that had recently 

faded from the radar replay, that 

appear to correlate with the position 

of the 2 SW’ly contacts reported by 

DEP. Although the guidance material 

to CAP 774, Chapter 3, paragraph 5 

states that ‘Controllers shall aim to 

pass information on relevant traffic 

before the conflicting aircraft is within 

5 NM’, given the flow of RT between 

DEP and both the Tucano Formation 

and the unrelated Tucano, it is 

reasonable to argue that the TI was 

passed as early as possible. Moreover, given the relative speeds of the aircraft, the provision of 

TI within 5nm had no bearing on the incident outcome. 

Between 1500:46 and 1501:12, DEP was involved in an exchange of RT with a further Tucano 

pilot who had departed LIN. Immediately thereafter, the Tucano Formation leader requested DEP 

to “say again the er north-westerly traffic again please.” DEP replied, “previously called traffic in 

your 12 o’clock, 1 mile, crossing right-left, converging, no height information” which was 

acknowledged. Approximately 6sec later, at 1501:31, a second voice was heard on the RT 

saying “visual…below us now…clear now”; this voice was subsequently assessed as being the 

Tucano Formation wingman. In subsequent 

conversation with the wingman, he advised 

that the passenger on board his ac visually 

acquired the glider and cued him to its 

position before he reported visual. The 

glider was reported as passing ‘directly 

beneath’ the formation, ‘with an estimated 

height split of 200-300 ft’. The Formation 

leader expressed his concern that ‘despite 

having the radar service and directing all of 

[his] attention towards lookout, [he] never 

became visual with this glider’. Figure 2 

depicts the incident geometry at 1501:13, as 

the Tucano Formation leader requested 

updated TI on the “north-westerly traffic”; 

the circled primary contact, believed to be 

the incident glider, was 1.7nm from the Figure 2: Incident Geometry at 1501:13. 

Tucano Formation. This contact faded from 

the radar replay at 1501:24. 

From an ATM perspective, by specifically using the word ‘converging’ DEP appears to have made 

good use of the amended TI phraseology in CAP 413 Edition 21 to highlight his perception of a 

‘significant risk of mid-air collision’. 

Comments 


Figure 1: Incident Geometry at 1500:23. 

The traffic information passed to the Tucano formation by ATC allowed prioritisation of lookout 

towards the highest threat, unfortunately without success until the formation was close to the 

3

glider. Whilst both civilian and military aircraft are equally entitled to usage of this airspace, it is 

disappointing that the heavy investment in regional liaison by RAF Linton-on-Ouse did not yield a 

better level of coordination between the 2 parties. Had the gliding competition task routing 

remained clear of the RAF Linton-on-Ouse departure and recovery lanes then the risk of mid-air 

collision may have been further mitigated (though it is accepted that the Airprox glider may have 

been unconnected to the reported competition). Of note, the delay in reporting the incident as an 

Airprox had reduced the fidelity of the Airprox reporting process. 

Summary 

A Tucano formation and an untraced glider flew into confliction, 5nm west-north-west of LIN. The 

Tucano formation were operating under VFR, in receipt of a Traffic Service from LIN DEP. 


Information available included a report from the Tucano pilot, transcripts of the relevant RT 

frequencies, radar video recordings, reports from the air traffic controllers involved and reports from 

the appropriate ATC and operating authorities. 

Members considered the pilots’ actions first. The Tucano formation leader was operating under a 

Traffic Service with ‘Glider Ops’ in force at Linton. His departure from the airfield was normal, and he 

was given traffic information (TI) on contacts to the south-west and north-west. The TI for the 

conflicting glider, to the north-west, was first passed about 1min before CPA. Members felt that the 

Tucano pilot may not have correctly assimilated the traffic’s position, demonstrated by him rolling out 

of his initial right turn pointing at this north-westerly traffic, his request for updated TI, and his 

recollection of that TI indicating traffic to the north-east. Members noted that if the pilot was unsure 

about the position of the traffic, and hence unsure as to an appropriate direction to turn, he could 

reasonably have requested a Deconfliction Service, rather than requesting updated TI. 

Turning to the glider pilot, members were disappointed to note that the glider pilot could not be 

traced, especially given the degree of regional liaison by RAF Linton-on-Ouse. Glider pilot members 

noted that the subject glider pilot may well not have been based at a local airfield, and also noted that 

the glider pilot could equally well have observed the formation passing and assessed the situation as 

benign, therefore not believing that an Airprox report was appropriate. In the absence of information 

from the glider pilot it was impossible to determine whether he or she had seen the formation and, if 

so, whether the pilot either took avoiding action or considered the miss-distance ‘acceptable’. The 

delay in filing the event as an Airprox may have been a factor in identifying the glider pilot since 

tracing action taken at the time might have been able to link the glider to a particular competition task. 

Members assessed that the ATS had been appropriate for the conditions and that the LIN DEP had 

passed timely and appropriate TI, albeit probably not fully assimilated by the Tucano pilot. 

In the absence of information from the glider pilot, the Board determined that the Airprox was due to a 

conflict in Class G airspace but that, although safety margins were reduced, they had not been ‘much 

reduced’ below normal. 


Cause: 

A conflict in Class G airspace. 






4



Position: 

5828N 00508W 

(10nm SW Cape Wrath) 

Airspace: Scot FIR (Class: G) 

Reporting Ac 

Reported Ac 

Type: Tornado GR4 AS350 

Operator: HQ Air (Ops) Civ Comm 

Alt/FL: 265ft amsl 800ft 

NK 




1200ft V/20ft H 


NK 

Not Seen 

Tornado 

low-level 

Tornado track fades 



NM 

0 2 4 

1502:12 

02:24 

02:36 

CPA 1503:08 

AS350 

1200ft alt 


THE TORNADO PILOT reports operating autonomously under VFR in VMC, listening out on the lowlevel 

common (LLC) frequency whilst in the process of taking a positional fix at low-level. The grey 

camouflaged aircraft had navigation and obstruction lights set to ‘maximum conspicuity’ and dorsal 

and ventral HISLs selected on. The SSR transponder was selected on with Modes A, C and S; the 

aircraft was not fitted with an ACAS. In level cruise, at 265ft amsl, 400kt, heading 110°, the pilot saw 

a helicopter appear from behind his canopy arch, just above and to the right of his track at a range of 

about 1nm. He described the helicopter as being black with a white stripe on top, and having skids 

and a ‘Wescam or similar’ slung underneath. He assessed that the helicopter was approximately 

1000ft above. Post-flight examination of the Tornado head-up display video placed the helicopter at 

approximately 1500ft amsl, stationary, pointing in the same direction as the Tornado, and positioned 

in the middle of the coastal inlet into which the Tornado was heading at the time. The Tornado pilot 

assessed that the safest course of action was to continue straight ahead at low-level, passing an 

assessed 1200ft below and 20ft to the side. Once clear, the crew continued with the briefed task. The 

Tornado pilot stated that he had maintained a listening watch and had made regular calls on LLC 

during the flight, the last of which had been 4min before CPA with clear line of sight to the helicopter's 

position. He noted that the positional fixing routine was a potential distraction to his lookout. 


THE AS350 PILOT reports in the cruise at 800ft, heading south at 80kt. The helicopter colour 

scheme, lighting state and TCAS fit were not reported. The SSR transponder was selected on with 

Modes A and C. The pilot was operating under VFR in VMC. He did not report the radio frequency 

selected or whether he was in receipt of an ATS. He stated that he did not see a military aircraft. 


The weather at Stornoway was recorded as follows: 

METAR EGPO 071450Z 06007KT 9999 FEW018 SCT042 15/11 Q1018 

METAR EGPO 071520Z 06007KT 9999 FEW024 15/11 Q1019 

1



The time of CPA (1503:08) was calculated from radar recordings of both aircraft and by 

extrapolating the Tornado track on the assumption that its heading and groundspeed remained 

constant after the track faded at 1502:36. Both pilots were equally responsible for collision 

avoidance, 1 and the AS350 pilot had right of way 2 . Whilst military fast-jet crews are required to 

monitor the LLC frequency whenever possible when operating in the UK Low Flying System 3 , no 

such requirement exists for civilian traffic operating below 2000ft agl/amsl. 

Comments 


This incident underlines the importance of effective lookout at all stages of the sortie, including 

when conducting specific training requirements. On this occasion, a small ac, obscured by the 

canopy-arch and vertically mis-aligned with the flight-path of the Tornado, was seen and avoided, 

albeit at a late stage. The Tornado crew adhered to all the mid-air collision mitigation procedures 

expected of them; TCAS could have enhanced awareness of this potential conflict. 

Summary 

A Tornado GR4 and AS350 flew into proximity at low-level at 1503 on 7 th August 2013. The Tornado 

pilot assessed that his flight path would take him clear; the AS350 pilot did not see the Tornado. 


Information available included reports from the pilots of both ac and radar video recordings. 

Military pilot members felt that a combination of factors had resulted in the Tornado pilot filing this 

Airprox. Firstly, he was probably task-focused on the positional fix, which may have reduced his 

lookout at that stage of the sortie, and was startled to see a helicopter appear at low-level from 

behind the canopy-arch. Secondly, having made appropriate calls on the LLC frequency, he had a 

clear expectation that the helicopter pilot should have heard his transmission (having reported that he 

was ‘line-of-sight’ to the helicopter when he made his last call). The Board noted that the LLC is a 

UHF frequency and that this AS350 was not fitted with a UHF radio, as is the case for almost all 

civilian aircraft. The Board also noted that, in any case, there was no requirement for the helicopter to 

monitor LLC even if the aircraft had been fitted with UHF. 

Nevertheless, having seen the helicopter at a range of 1nm, about 11sec from CPA at the reported 

speeds, the Board members agreed that the Tornado pilot had taken the most appropriate course of 

action in maintaining his track and altitude to pass well clear, below the AS350. The helicopter pilot 

had no recollection of seeing a military aircraft. 

Given the reported separation of more than 1000ft vertically allied to the lack of concern from the 

AS350 pilot, members felt that normal procedures, safety standards and parameters had pertained. 


2 ibid. Rule 11 (Overtaking). 

3 The UK Low Flying System comprises Class G airspace extending vertically from the surface to 2000ft agl/amsl and 

laterally to the UK FIR boundary. UK Military Low Flying Handbook, dated 8 th March 2012. 

2


Cause: 

Sighting report. 

Degree of Risk: E. 





3



Position: 

5131N 00007W 

(6nm W London/City Airport 


Airspace: London City CTR (Class: D) 

Reporting Ac 

Type: RJ1H A109 

Reported Ac 

Operator: CAT Civ Exec 


QNH 

NK 

Weather: VMC CLBC VMC CAVOK 

Visibility: >10km >10km 


500ft V/0nm H 


500ft V/0.7nm H 

NK 

A109 

1500ft alt 

1145:34 45:58 

45:46 46:10 

CPA 1146:22 

500ft V/0.7nm H 

RJ1H 

2000ft alt 



3 

2 

1 

0 

NM 

LCY RW09 C/L 


THE RJ1H PILOT reports inbound to London City airport (LCY) under the control of Thames Radar 

(combined with City Radar), frequency 128.02MHz. Landing, strobe and navigation lights were 

illuminated. SSR Modes C and S were selected, squawking 3011. He was on an intercept heading for 

approach to RW09. After receiving traffic information (TI) from ATC, he received an RA ‘monitor 

vertical speed’. Range of vertical speed ‘zero to up 500ft/min’. In VMC, he continued level flight 

without correction and clear of conflict he continued his normal ILS steep approach into LCY. He did 

not observe the other aircraft. 


THE A109 PILOT reports that the helicopter, coloured predominately white, had the red anti-collision, 

strobes and navigation lights illuminated. SSR Modes C and S were selected. He was transiting the 

LCY CTR, VFR, in communication with SVFR/Thames Radar, frequency 125.625MHz. He was 

unaware of being in close proximity to a Regional Jet and did not remember this particular flight. He 

commented that he probably crosses the City Zone 4 times a week. However, looking at his flight log 

from Skydemon software it appears that on this occasion he transited the City Zone not above 1500ft 

from Alexandra Palace to the London Eye and then south to leave the zone. He commented that it is 

not unusual to be co-ordinated 500ft below traffic inbound to LCY. Nothing was said on the radio at 

the time, as far as he could remember. 


The London City weather was: 

EGLC 071620Z 01008KT 320V060 CAVOK 21/09 Q1014= 

EGLC 071650Z 04007KT 330V100 9999 FEW049 21/09 Q1014= 

1

MATS Part 1 1 states the ATC responsibilities for Class D airspace:’....Pass traffic information to IFR 

flights on VFR flights and give traffic avoidance advice if requested; Pass traffic information to VFR 

flights on IFR flights and other VFR flights’. 


CAA ATSI 

CAA ATSI had access to written reports from both pilots, area radar recordings, RTF recordings 

and transcripts of the City Radar/Thames Radar frequency and the LTC SVFR frequency. No 

controller reports were received. 

At 1641:40 the A109 pilot was given a clearance to transit controlled airspace southbound not 

above altitude 1500ft, VFR, via Alexandra Palace and the London Eye. The A109 pilot was 

instructed to look out for IFR traffic on right-base for RW09 at London City, which would be 500ft 

above. 

By 1644:40 the RJ1H pilot had been instructed to turn onto a heading of 360° and had been 

passed traffic information (TI) on the A109 as “approaching from the north a helicopter will transit 

southbound not above one thousand five hundred feet VFR” (Figure 1). This was acknowledged 

by the RJ1H pilot. The A109 pilot was passed updated TI on the RJ1H as being 6nm south and it 

would be turning right eastbound for the ILS. 

Figure 1 

At 1645:10 low level Short Term Conflict Alert (STCA) activated and at 1645:33 the A109 pilot 

reported visual with the RJ1H (Figure 2). The A109 pilot was informed that the RJ1H was just 

turning eastbound at 2000ft, descending on the ILS, and that “if you route behind that traffic it’ll 

help”. This was acknowledged by the A109 pilot. 

1 MATS Part 1, Section 1, Chapter 2, Page 2 

2

Figure 2 

The RJ1H pilot was instructed to turn right heading 060° and cleared for the ILS approach. This 

was read back by 1645:40 (Figure 3). 

At 1645:57 high level STCA activated. 

Figure 3 

At 1646:05 the A109 pilot reported being “well behind” the RJ1H (Figure 4). 

3

Figure 4 

Summary 

The Airprox occurred within Class D airspace. The RJ1H was operating on an IFR flight inbound to 

RW09 at LCY. The A109 was transiting the LCY CTR VFR, from north to south, crossing west of the 

airport. The controllers complied with their responsibilities for IFR/VFR traffic operating in Class D 

airspace i.e. TI was passed to the pilots of both aircraft. There is no requirement to provide standard 

separation between such flights. The RJ1H received a TCAS RA to monitor vertical speed and the 

A109, obtaining visual contact with the RJ1H, passed behind it. 


Information available included reports from the pilots of both aircraft, area radar recordings, 

transcripts of the relevant RT frequencies and reports from the appropriate ATC and operating 

authorities. 

Before considering the Airprox itself, Board members commented that a number of similar Airprox 

reports had been filed by pilots of the operator of this RJ1H. All bar one involved aircraft inbound to 

RW09 at LCY receiving TCAS RAs concerning VFR aircraft 500-600ft below them in, or close to, the 

LCY CTR. It transpired that the associated airline’s company mandatory occurrence reporting form 

automatically links the reporting of TCAS RAs to the reporting of Airprox. 

The Board then considered the specific actions of the pilots on this occasion. Turning first to the 

RJ1H, the Board noted that this aircraft was inbound, IFR, to LCY and routeing to the ILS RW09 at 

2000ft. ATC had informed the pilot about the A109, which had him in sight. The Board noted that the 

RJ1H pilot did not observe the A109 and that, subsequently, the RJ1H had received a TCAS RA 

because of its presence despite the fact that both pilots were complying with their respective 

instructions and operating normally within the airspace. The RJ1H pilot did not alter his flight profile 

as a result of the TCAS alert, because the associated RA instruction was simply to monitor vertical 

speed - level flight was within the required parameters. An airline pilot member confirmed that, as in 

other similar events, this was appropriate action to take in the circumstances. 

Turning next to the A109 pilot, the Board noted that he had stated that he regularly transited the LCY 

CTR and that, although he could not recollect this flight, his log confirmed he was routeing south at 

1500ft, in accordance with his ATC clearance, to pass west of LCY. The Board noted that he could 

not remember being in close proximity to RJ1Hs in general, was visual with the subject RJ1H, and 

was unconcerned about the incident. The RTF recording confirms that the pilot had been informed 

4

about the RJ1H, and he had reported it in sight. In all respects, the A109 pilot considered this to be a 

routine flight with no unusual Airprox aspects. 

Finally, with respect to ATC, the Board considered that the TC City/Thames Radar and SVFR 

controllers had both complied with their overall responsibilities and had passed appropriate traffic 

information to both flights which were conducted under normal procedures and separation standards 

for the airspace involved. In the event, 500ft vertical and 0.7nm horizontal separation had been 

achieved even though there was no specific requirement so to do. 

The Board members agreed that the Airprox had been reported because of the TCAS RA received by 

the RJ1H due to the A109’s flight vector. They unanimously agreed that this was a TCAS sighting 

report. In view of recent similar Airprox being assessed as a Category E (normal procedures, safety 

standards, and parameters pertained) it was decided that this Airprox should also be similarly 

categorised. However, irrespective of the benign circumstances surrounding this particular event, the 

Board were concerned that it should not be considered normal procedure for aircraft being vectored 

within the LCY CTR to receive TCAS RAs lest pilots become inured to what might become 

normalised routine behaviour rather than reacting fully to TCAS alerts. A number of members also 

commented that this type of occurrence could easily occur at other airports within Controlled Airspace 

and should not be considered unique to LCY, especially with the potential increase in Class D 

airspace that might be introduced at other regional airports in future. Therefore, in conjunction with 

Airprox 2013095 and 2013099 (also assessed during this Board), they decided to generate an 

overarching recommendation that the CAA reviews VFR/SVFR traffic procedures within CAS with 

respect to RA occurrences in TCAS-equipped aircraft. 


Cause: 

Risk: 


E 








5

20131211-2013.12Reports

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