Hey Bob,
Hows it going?I am a ME/CIR pilot now thanks to you and your books.My personal thanks to you.I have an airline interview coming up pretty soon and wanted to ask you a question on Minimum safetly altitudes.If the 10NM MSA is higher than the 25NM MSA whats the point?Do i just maintain the 10NM MSA since its higher?
For example WILLIAMTOWN NDB-Z rw 30 APP says 3100 on the western quadrant and 1500 on the eastern but 2100 as 10NM MSA.Any tip on this would be much appreciated.

Cheers,
Sandeep

If the MSA for a sector is lower than the 25nm or 10nm MSA, you can use that lower MSA all the way to the aid as long as you stay in that sector. Using your example, if you remain between the 350* and 270° bearings, you could ignore the 3100 and 2100ft MSAs and maintain 1500 feet to the aid.

However, you would only do this in an attempt to break free of cloud and continue with a visual approach. If you think it will be necessary to do the NDB approach, there would be no point in descending to 1500 feet, even though you could legally do that. This is because you can't begin the NDB procedure below 3100 feet.

Hi Bob,

Yes i totally understand your answer but what's the reason for having a 10NM higher MSA?Also Jeppesen states that the 25 NM MSA is used only under emergency and we have to use the route LSALT or Grid Until station passage.
Any help will be much appreciated

MSA / MINIMUM SAFE ALTITUDE
Altitude depicted on an Instrument Approach Chart and identified as the minimum altitude
which provides a 1000 ft obstacle clearance within a 25 NM radius from the navigational
facility upon which the MSA is predicated. If the radius limit is other than 25 NM, it is
stated.
This altitude is for EMERGENCY USE only and does not necessarily guarantee NAVAID
reception.
When the MSA is divided into sectors, with each sector a different altitude, the altitudes in
these sectors are deferred to as "Minimum Sector Altitudes".

I must admit I was not aware of that Jeppesen reference. I don't understand what they're on about. Why would you be talking about guaranteeing nav aid reception when you are within 25 nm of the aid? In any case, nobody ever said that LSALT guarantees nav aid reception either. What about the case when LSALT for the route is lower than MSA. Does that mean you can not climb up to MSA unless there is an emergency? Makes no sense. As far as I know, there is no such reference in the AIP or DAP and that is what any exam question is based on.

Bob