Aeronautical study - part 2

28.10.2004

Submission:

I have a question regarding Annex 14 OLS surface criteria. Is a taxiing or holding (not parked) aircraft that penetrates the Annex 14 Approach Surface considered an obstacle? For example, if you displace the threshold of the runway, portions of the parallel taxiway or hold lines at the physical end of the runway (the portion before the displaced threshold) may now be under the Annex 14 Approach Surface. An aircraft tail may penetrate the approach surface as it is taxiing to the physical end of the runway or holding at the physical end of the runway waiting to takeoff. Is the aircraft considered an obstacle and does a SARPs non-compliance issue exist?


Robert W. Kleinhans - The MITRE Corporation - USA

Answer or Commentary:

(I.W.

I think the important paragraph in Annex 14 is:

"3.8.7 Recommendation. - The separation distance between the centre line of a taxiway and the centre line of a runway, the centre line of a parallel taxiway or an object should not be less than the appropriate dimension specified in Table 3-1, except that it may be permissible to operate with lower separation distances at an existing aerodrome if an aeronautical study indicates that such lower separation distances would not adversely affect the safety or significantly affect the regularity of operations of aeroplanes. velocity may cause hazardous conditions for ground servicing."

I think this Recommendation brings us back to the discussion above. I personally would consider an aircraft in such a case an obstacle and treat it as such. Pans-Ops also deals with holding aircraft in the ILS case, following is the Pans-Ops table.

I think this table seems to say that if the above minimums are infringed then the aircraft becomes an obstacle and must be taken into account in the OCA/H calculations.)