Mountainous Terrain Application in Holds 3

12.10.2011

Submission:

The issue described is not really an issue. It results from the application of the doubled MOC concept when the highest obstacle is in the primary or first buffer area. An example:
Your highest obstacle is in the primary area. You apply a 600m MOC to get the minimum holding altitude. That will automatically result in an MOC in the buffers that is way more than double in the buffers two till five.
The important thing is that the minimum holding altitude you calculate provides at least a doubled MOC over ALL obstacles in ALL areas. If for example your highest obstacle is in the third buffer, you provide an MOC of 2*120m=240m. The question is now: Does the MHA so derived provide a doubled MOC over every obstacle in the respective area (i.e. is the MHA really 600m above the obstacles in the primary and the first buffer, is it really 300m above the obstacles in the second buffer, is it really 180m and 120m over the obstacles in the fourth and fifth buffer respectively.
We (the IFPP) do not think that the criteria are not clear, you are probably just thinking too far :-). Of course, the provided diagram in Pans-Ops, assumes the controlling obstacle to be in the primary area. So the illustrated MHA of course shows an MOC increased by 300m in the buffers two till five. It would be too much to provide diagrams for each and every case. Please note that PANS-OPS is criteria and not guidance material.


Beat Zimmermann - Chairman of the IFPP - Air Navigation Institute GmbH - Switzerland


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