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Is there a Disarm Autobrake Offset???


Pantu
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just a short question:

Is there an offset for "Autobrake disarm" ?

The std B737 from MS has got: RTO; OFF, 1;2;3;4

Disarming the autobrake is setting it to OFF. The offset is documented (2F80) and the value 1 written to the byte there with disarm the autobrake.

For programming on a button or key, FSUIPC's Buttons and Keys pages offer an extra control (in the dropdowns) to operate the AutoBrake -- "Autobrake Set". To disarm, assign this with a parameter of 1.

If you are instead asking about the indicator light called "Autobrake Disarm" on the A/B Control Panel, you would need to program that for the applicable conditions (for instance, it can be done with pmSystems). All I know is the 737NG. The light should come on when:

* Manual brakes are applied during RTO or landing. The autobrakes should disarm automatically (FS doesn't do this, but some add-on aircraft do).

* Three seconds after thrust levers are advanced, after touchdown (again, the A/B does disarm)

* RTO is selected on the ground. The light only comes on for 2 seconds. This is just a test.

* There's some malfunction in the A/B system which prevents correct operation.

Regards,

Pete

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Hi Pete,

thank you very much for your prompt answer. Super service!!!

Reason why I asked that question is, that I´m using the Autobrake HW panel (747) from Cockpitsonic, which has positions like:

Rto; Off; Disarm; 1;2;3;4; Max Auto

The "disarm" puzzles me.

Will probably have to ask Cockpitsonic why they implemented that pos.

Thanks

Best rgds

Peter

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Reason why I asked that question is, that I´m using the Autobrake HW panel (747) from Cockpitsonic, which has positions like:

Rto; Off; Disarm; 1;2;3;4; Max Auto

The "disarm" puzzles me.

Ah, yes. According to my references for the 747, that arrangement is correct. A real 747-400 manual I have states this:

OFF = Disarms and resets the system

DISARM = Disarms and releases all brake pressure to the wheels.

Subtle, eh? :-) Quite honestly I don't know what pressure should be applied to the wheels in the OFF position in any case -- there shouldn't be any, in my reckoning. So the difference seems zero to me, at least as far as manually SELECTING it is concerned.

However, it goes on to say that the system itself selects that postion in similar cases to those for which, on the 737, the "Disarm" light comes on.

In other words, I think it is more of an indication to you of the "disarm" condition than it is a position which you'd ever normally select manually (except maybe for engineering purposes).

Perhaps, by the time they got to glassing the 737s they realised they didn't need a separate Disarm selector, only the light, for economy? (There's no similar light on the 747 A/B panel).

As far as FS is concerned I think you'll just have to treat it as "OFF" when selected. If the switch is motor-driven you could select disarm programmatically in the cases I listed previously, as the indicator.

Regards,

Pete

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