Drift-down/climb-out area procedure
 

Hi guys,

I didn't understand the drift-down procedure and climb-out areas.
Could you please explain me that ?

Thank you.

Nobody knows ?

Your question was asked recently on another website.

The response was to go to the following address and download the AIRBUS PDF "Getting To Grips With Aircraft Performance".

Getting to Grips With Aircraft Performance

I do not know if you were the originator of the question in both websites, but the similarity in the wording in the two sites suggests that this might be the case.

Before composing this message I went to the other website, followed the link and downloaded the AIRBUS PDF. Although it takes quite a while to download, it really is a very good book. If certainly includes quite a good description of drift-down.

I suggest that you download the AIRBUS document and read the section of drift-down. If you still have any more specific questions on the subject you can then post them here, and hopefully get a suitable explanation.

Not a perf expert but basic gist of driftdown is to use the aircraft energy in one of three ways:

to clear enroute terrain - usually achieved by selecting maximum continuous thrust on the good engine, letting the aeroplane speed reduce towards L/D Max (green dot on some types) and then selecting a speed on elevator mode (flch, open descent etc). As you descend into more dense air the good engine is able to deliver more thrust leading to an ever shallowing descent until you eventually reach driftdown altitude.

max range driftdown - applicable to ETOPS. Involves sticking to a particular speed schedule to maximise the range of the aircraft during driftdown to get as close as possible to a suitable enroute diversion

relight envelope - descending within a particular speed range in order to perform a windmill assisted start