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main_dog
11th Dec 2009, 10:34
Hello all,

Does anyone know how the B744 autobrake works in terms of programmed deceleration? A previous type I was on (from "Brand A" :}) specified the target deceleration rates for the various settings (believe it was 1.7m per second squared for Low, and 3.0m per second squared for Medium).

Does the Boeing autobrake aim for a target deceleration rate or a target brake pressure? If it's the former, any idea what these are?

MD

Jumbo Driver
11th Dec 2009, 11:01
With regard to Autobrake operation on the B744, my TM says ...

The RTO (rejected take-off) position provides maximum braking.
Also that ...

Landing autobrakes are armed by positioning the Autobrake Selector to one of the landing deceleration rates.

I'm afraid I have no information on the numbers involved. My guess is that on MAX setting, it is not a deceleration rate that applies but the maximum braking that surface conditions and antiskid will allow. However, I can tell you that, on landing, the MAX setting is impressive!


JD
:)

Mac74
11th Dec 2009, 11:34
Autobrake deceleration rates:

1 - 4.0 ft/sec^2
2 - 5.0 ft/sec^2
3 - 6.0 ft/sec^2
4 - 7.5 ft/sec^2
max - 11 ft/sec^2

Spanner Turner
11th Dec 2009, 20:20
If you really want the "nitty gritty", then have a read of a previous post here:

http://www.pprune.org/tech-log/287687-qantas-747-400-sop.html#post3476982


Enjoy.

:ok:
.

main_dog
12th Dec 2009, 01:14
Thanks guys! :ok: