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-   -   Autobrake on a 737 (https://www.pprune.org/questions/47066-autobrake-737-a.html)

eludlow 29th Nov 2000 23:30

Autobrake on a 737
 
I wonder if any here has a copy of the chrat issued in 737s (preferably 737-400s) that says what speed what autobrake setting goes to?
If they do, I would be VERY grateful if they wold send me the speeds on them.
Thanks,
Edward Ludlow

The Boy Lard 29th Nov 2000 23:48

Hi Ed,

Excuse me for being sceptical about your identity, but yesterday you posted as a 13 year old looking for schooling advice and today you want the Autobrake speed for a 737-400.
Why do you want this information (Not that I have it)and indeed if you are genuine accept my apologies.

TBL

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Flying is fun, not funny

The Boy Lard 30th Nov 2000 00:28

Ive just "spoken" to Ed, and he needs the info for Flight Sim, so if anyone can help??????

TBL

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Flying is fun, not funny

Nightstop 30th Nov 2000 19:38

OK, here goes:

Autobrake Selector, Brake Pressure PSI, Deceleration Rate in ft/sec/sec :

1, 1250, 4

2, 1500, 5

3, 2000, 7.2

MAX, 3000, 12 ft/sec/sec below 80 kts

MAX, 3000, 14 ft/sec/sec above 80 kts

RTO, FULL System pressure, Deceleration Rate Not Controlled Brake Pressure is Max System pressure with "on ramp"

There is an "on ramp" period where Autobrake pressure is applied over a period of time. Approximately 750 psi is applied in 1.75
sec then above mentioned pressures are reached in another 1.25sec for Autobrakes 1, 2, or 3 and approx. 1.0 sec for MAX. There
is a logic that says average wheel speed must be greater than 70kts to initiate Autobrakes. There is some confusion that it takes more brake pedal pressure than is being applied by the Autobrakes to disarm. A more accurate statement is that it takes 750 psi of brake pedal pressure at the brake shuttle valve to disarm any
Autobrake/RTO application. I hope this information is helpful.
The Autobrake system is much more complex than two paragraphs can describe.

eludlow 30th Nov 2000 20:52

Thank you Nightstop!

mearse 30th Nov 2000 23:16

Can anyone tell me how this information can help either a pilot of a plane or FS2000.

The question should be... can i land in xxxx of runway...

Mearse

Sick Squid 1st Dec 2000 17:16

Mearse,

Once you've answered that question, the autobrake distance table allows you to select a suitable autobrake setting to give a smooth deceleration to your chosen exit point on the runway. For instance, you may want to leave at a rapid exit taxiway 2/3rds down the runway.



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Disappears in a cloud of black ink...


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