Acceleration altitude

28.10.2004

Submission:

After reading the Jeppesen ATC section (page 201) concerning PANS-OPS, I am left with some doubt with the engine-out missed approach on a PANS-OPS 4 Instrument Procedure.

Quote from Jeppesen:

PANS-OPS 4 - further indicates that the acceleration segment criteria have been deleted, as formerly published in ICAO Document 8168 Volume II, First, Second and Third Editions.

Does this at all affect the levelling off and cleaning up procedure at acceleration altitude, during an engine-out missed approach ?


Andre van Rensburg
Mauritius

Answer or Commentary:

(I.W.

Just a couple of points to this question. ICAO Pans-ops criteria does not take into account the situation of an engine out. Procedure designers only design procedures for all engines operating and it is the requirement of the operator to develop company, aircraft and airport specific engine out procedures. However the ICAO Pans-ops criteria is quite stringent as far as obstacle clearance goes. For example the standard departure climb gradient is 3.3% and the missed approach gradient is normally 2.5%. Most modern aircraft can accomplish these climb gradients even with an engine out.

It is correct that the acceleration section of the departure has been removed from the ICAO departure criteria and procedures are designed with a continuous climb. However there is nothing to stop a pilot arranging his flight to include an acceleration altitude as long as it is calculated correctly. All that has to be accomplished is that the aircraft remain above the Procedure Design Gradient (PDG - normally 3.3%).

Let me re-emphasise that this acceleration portion must be calculated to remain above the PDG. Does anyone know of airlines that actually calculate acceleration positions/heights?)