Procedural separation

25.10.2004

Submission:

I am an ATCO with no experience in procedure design except attending a course on PANS-OPS. I need to know how are the primary areas of the race-track holding pattern applied to obtain standard separation between the pattern themselves and from the air routes? I can use VOR/DME and NDB. Also, how, if possible, are the tolerance areas of a airway defined by a VOR track or NDB track applied to obtain standard separation with another airway or reserved airspace? Thank you very much for your assistance.

Ting Huat Ngi

Answer or Commentary:

(I.W.

As far as I know lateral separation of Holding patterns / airways is set down in National criteria and is not really covered in the ICAO documents.

For holding patterns the usual adopted criteria is if the primary obstacle protection areas of the two holding patterns do not over lap then the holding patterns are deemed to be procedurally separated up to the altitude at which they were constructed.

However other countries also include not only the primary obstacle protection areas but also the 5nm buffer area.

The same general criteria are often applied to not only holding patterns but also routes and airspace.

The only place that I could find actual ICAO lateral route separation was in ICAO document 4444 (ATC). There was stated that the procedural separation for NDB tracks diverging by more than 30 degrees is 15 NM.

It is interesting to note that the 15 nm position is exactly ( + 100m) the point where the Pans-Ops obstacle protection areas separate.

Does any one else have examples of National criteria or knowledge that the 30° and 15nm did in fact come from the Pans-Ops criteria?)