This question relates to the Revision Set 7, Question 7.

The question asks what is the lowest level to maintain until the IVL NDB following a RAIM warning at 6nm to run on the GPS arrival. The missed approach procedure is to turn to track 300 deg and climb to 4300'.

The segment minimum safe altitude at the time of receiving the warning was 4000'.

ENR 1.5 para 1.10.2 says that if the missed approach is initiated prior to arriving at the MAPT, you must fly to the MAPT and then follow the missed approach procedure. The AIP doesn't seem to say anything about when to initiate the climb, if the procedure is commenced prior to the MAPT (although I guess that common sense dictates that you commence the climb whilst tracking to the aid, and para 1.12.1 say to commence the procedure immediately).

I chose answer (d), being 4000' as the minimum altitude to track TO the NDB, prior to commencing the missed approach procedure. The answer in the book lists (b) on the basis that you would need to climb to 5100' to commence the NDB, however I don't think that this really reflects what the question is asking??

The AIP is a bit vague here [as it often is]. The missed approach is surveyed assuming the procedure is initiated from the missed approach point. You are not at the missed approach point so the published missed approach would not be valid. You are within the 10nm MSA however, so you should climb to that height [5100ft] to ensure safety.

Thanks Bob.