20131211-2013.12Reports

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°.
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