Holding Areas 1

28.10.2004

Submission:

I have read the thread concerning holding areas and while it is not laid down formally in Australia, the following is my personal understanding of the application of PANS OPS. Followed by my own personal opinion on how holding pattern lateral separation may be achieved: I understand the PANS OPS primary area to represent (at least) 2 standard deviations (SD or sigma) protection for the speed and level selected. The 5NM buffer (reducing vertical MOC for each NM) on holding areas provide the additional lateral and vertical protection required for 3 sigma protection as per PANS OPS.

The basic lateral separation standard is 1NM between the possible positions of two aircraft (i.e. taking their (2 sigma) navigation errors into account). This would follow then that two holding patterns (or splays of other procedures) can be considered laterally separated when there is 1NM between the primary PANS OPS areas. This would seem to be getting into the area of ATC applications as well as procedure design, but I would be interested to hear the opinion of other specialists in this area.

P. Bushell

Procedure Designer, Royal Australian Air Force Aeronautical Information service, Melbourne, Australia

Answer or Commentary:

(I.W.

ICAO Rules Of The Air and Air Traffic Services (Doc. 4444) states that procedural separation of traffic on NDB routes diverging by more than 30 degrees occurs at 15 nautical miles.

It is interesting to note that the 15 nautical mile position is exactly where the two obstacle protection area splays separate. Is this merely a coincidence or is that how this separation was determined?)