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Jepps Trivia

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Well-known member
Nov 26, 2001
A while back on the old board, the question was raised about the naming of approach procedures and the significance of letters following the navaid in procedure titles (i.e. VOR-A, ILS-Y). I searched long and hard for the answers, but found nothing specific. Also, I don't recall any valid answers being posted.

In the November Pro Pilot, I came across a Q&A that addresses the question. The ILS Y Rwy 19 plate at KVPS is shown, and the following question (among others) is printed:

"The 'Y' in the procedure identification signifies_____

a. this is a military approach
b. FMS-equipped aircraft can execute this approach
c. there are at least 2 ILS approaches to Runway 19
d. all of the above

anyone want to take a stab at the answer with an explanation before I post it? No peeking at the mag!
The answer would be C, there are 2 ILS approaches to RWY19. Similar to the VOR-A etc, letters of the alphabet are used but start at the end of the alphabet so the precision approaches are not confused with the non-precision ones, ie, ILS Z RWY 19 would be first. Since they are both precision approaches, they probably require different equipment to execute like an ADF or TACAN.



Here is the printed answer:

(c) In fact there are 2 ILS approaches to Rwy 19 using the letters 'Y' and 'Z' in the procedure identification. However, the ILS Z Rwy 19 is not published by Jeppessen because it requires TACAN, while the 'Y' procedure does not. The naming policy is to use a letter proceeding backward from the end of the alphabet. This prevents confusion with procedure identifications for approaches with circle-only minimums such as VOR-A, -B, etc.
Good gouge, but can anyone find where this is stipulated. other than the magazine article? Just one of those pilot things, I gotta know.

This is one of the many reasons that EVERYONE should contribute to this board. Great stuff!!!!

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