RNAV and conventional departures

08.10.2007

Submission:

Mixing conventional and P-RNAV departures on a SID. I have been looking at a proposed P-RNAV (DME/DME) SID. The designers have started the P-RNAV waypoint list at a VOR/DME some 5-6nm from the airport runway and given this waypoint the code 'IF' the following waypoints are 'TF's'. In order to bridge the gap between runway and the start of P-RNAV the pilot is expected to take off, climb on track to an altitude and then follow a VOR radial to the IF waypoint. Is it possible to combine a "conventional departure" with a P-RNAV SID like this ? I thought that the P-RNAV should start at the DER and use a FA, DF type construction to the VOR. Also 8168 says that the 'IF' is for coding purposes only and should not be published.

Andy Prime - Projects Engineer - Flight Precision Ltd –UK

Answer or Commentary:

(I.W.

I personally would have thought that the mixing of conventional and RNAV procedures in a single departure was not optimal. I would have thought that the procedure designer would have ensured that the initial part of the SID was also RNAV so that it would be coded as was originally intended in the design of the SID. However there may have been coverage issues. Especially with DME/DME RNAV procedures and that possibly the easiest way to get around this was to designate the first part of the procedure as conventional.)