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

Appendix A to Chapter 3
INITIAL APPROACH USING DEAD RECKONING (DR)
1. GENERAL
1.1 Purpose
1.1.1 A dead reckoning (DR) track procedure may be used to reduce the angle of turn onto the final approach
track where such a turn would otherwise exceed the limits specified in Part II, Section 1, Chapter 1, “Initial approach
segment alignment”. Its main purposes are:
a) to save time and airspace by avoiding a reversal manoeuvre;
b) to provide pilots with a comfortable flight pattern. The chances of overshooting the final approach track in case
of a suitably designed intercepting DR track are less than in the case of a large turn initiated by a lead radial;
and
c) to provide air traffic control (ATC) with flexibility by designing DR track segments of different length to
accommodate two ranges of speeds. This will allow a slower aircraft followed by a faster one to be assigned to
a shorter track to the advantage of both aircraft.
1.1.2 Several DR tracks may be designed using the criteria in this attachment. This allows ATC to vary the initial
track of the aircraft under radar surveillance by assigning a track number to the aircraft. And if radar vectoring is
required, this track will provide the ATC with a reference (on the radar scope) which shows the most appropriate way
to proceed from the initial approach fix (IAF) to the final approach point (FAP).
1.2 Required navigation facilities
This type of procedure requires either two VORs or a VOR/DME to define the fix from which the DR track begins.
Track guidance on final and intermediate approach may be provided either by VOR, NDB or localizer (LLZ). Because
this procedure is intended for use at major airports, it has been illustrated for the instrument landing system (ILS) case.
When any portion of DR segment between the nominal position of start point and the localizer course lies outside of the
service volume of the localizer, a homing facility close to the final approach track (for example at the airport) is
required.
Note.— In case of non-precision approach, the areas shall be adapted to the type of facility providing guidance on
final approach.
I-4-3-App A-1 23/11/06