View Full Version : NPA config
adm100
8th Aug 2007, 21:36
Does anyone know if there is a rule (ICAO/JAR/FAA etc.) about what config the a/c should be in when at the FAF on a NPA. My company rules say that we (A320) have to be fully configured, gear down and managed speed when over the FAF, but last time I did one me and the skipper couldn't work out if it was just company rules or something else.
No legal (well out of the EASA/JAR/NAA whathaveyou jam jar) requirement, just a demo of good airmanship (what a great word that is :cool:)
And the fully configured thing on the NPA might be a company requirement... but is above all an Airbus (FCOM) one :ok:
live 2 fly 2 live
OPEN DES
10th Aug 2007, 19:56
A regulatoty requirment, I highly doubt it. A company requirement/recommendation surely. Airmanship? Perhaps in IMC conditions...
The purpose of the requirement is to make the final descent involve less workload and to decrease the chance of messing up. Making a decelerated NP approach requires constant adjustment of the FPA because the actual flightpath angle of the a/c is lagging the selected FPA. This is caused by the changing config. Being fully configured and reduced to Vapp means that the only pilot task left really is to monitor the flightpath, which is a lot easier when at constant speed and in final config. The FPA vertical mode of the A320 only follows a target and does not constitute a trajectory! But fully stabilised it does a pretty good job.
However ATC wont't be very happy with you reducing to 120something 8 miles out. A good compromise is to be at least flaps 2 before the FAF. Flaps 2 in the airbus causes a huge pitch moment (not just slats now, but also flaps) and is relatively the most intrusive config change you can make in the A320s. You will see that approaching the FAF at flaps 2 and at selected speed 160 or decelerating through a similar speed will work very nicely. Once established on a nominal -3.0 FPA you will not significantly destablise the approach configuring further to final flap and Vapp tgt. Thus requiring minimal pilot input on FPA.
Regards