Aircraft Operations. Volume II - Construction of Visual and Instrument ...

I-4-1-2 Procedures — Aircraft Operations — Volume II
23/11/06
1.5 PROCEDURE ALTITUDE/HEIGHT
1.5.1 The aviation industry has identified that the majority of large aircraft accidents occur lined up with and
within 19 km (10 NM) of the landing runway. To support the Controlled Flight Into Terrain (CFIT) prevention
initiatives, instrument approach charts shall not only provide altitudes/heights to ensure appropriate obstacle clearance
but also procedure altitudes/heights. Procedure altitudes/heights are intended to place the aircraft above any minimum
altitude associated with obstacle clearance and to support a stabilized prescribed descent gradient/angle in the final
segment.
1.5.2 All non-precision instrument approach procedures shall be developed to include not only the minimum
altitudes/heights to ensure obstacle clearance, but also procedure altitudes/heights. Procedure altitudes/heights shall be
developed to place the aircraft at altitudes/heights that would normally be flown to intercept and fly the prescribed
descent gradient/angle in the final approach segment to a 15 m (50 ft) threshold crossing. In no case shall a procedure
altitude/height be less than any OCA/H.
1.6 TRACK GUIDANCE
1.6.1 Track guidance should normally be provided for all phases of flight through the arrival, initial, intermediate,
final and missed approach segments. When track guidance is provided, the appropriate segment shall lie within the
established coverage of the navigation facility on which the track guidance is based.
1.6.2 When track guidance is not provided the obstacle clearance area shall be expanded as prescribed for dead
reckoning (DR) segments in Chapter 3, “Initial approach segment” and in Appendix A to Chapter 3, “Initial approach
using dead reckoning (DR)”. Terminal area surveillance radar (TAR), when available, may be used to provide vectors
to the final approach (see Part II, Section 2, Chapter 6, “SRE”). En-route surveillance radar (RSR) may be used to
provide track guidance through initial approach segments up to and including the intermediate fix. Criteria for the
construction of areas for missed approaches without track guidance are provided in Chapter 6, “Missed approach
segment”.
Note.— Detailed procedures regarding the use of primary radar in the approach control service are set forth in the
PANS-ATM, Doc 4444, Procedures for Air Navigation Services — Air Traffic Management.
1.7 VERTICAL GUIDANCE
Optimum and maximum descent gradients are specified depending on the type of procedure and the segment of the
approach. At least in the case of the final approach segment for non-precision approach procedures and, preferably, also
for other approach segments where appropriate, the descent gradient(s) used in the construction of the procedure shall
be published. Where distance information is available, descent profile advisory information for the final approach
should be provided to assist the pilot to maintain the calculated descent gradient. This should be a table showing
altitudes/heights through which the aircraft should be passing at each 2 km or 1 NM as appropriate.
1.8 CATEGORIES OF AIRCRAFT
1.8.1 Aircraft performance differences have a direct effect on the airspace and visibility required for manoeuvres
such as circling approach, turning missed approach, final approach descent and manoeuvring to land (including base
and procedure turns). The most significant factor in performance is speed. Accordingly, five categories of typical
aircraft (see 1.8.4) have been established to provide a standardized basis for relating aircraft manoeuvrability to specific
instrument approach procedures.