Autobreak disarm action

[choffmann]

Hello,

does someone know, if - in the real 737 - the autobrake switch is spring-loaded to automatically disarm after landing, when the pilot either
-moves the speedbrake lever to down detent
-advances the throttles (>3s after touchdown)
-applies manual braking
?????
Or is it always selected "off" manually by the flight crew?


Chris

[Matt Olieman]

In an Airbus it's deactivated by tapping the toe brakes.

Matt Olieman

[ANDYSMITH]

If I remember correct, the switch does not move by itself, but applying manual braking greater than what the autobrake is set at turns off the autobrake and the "autobrake disarm" annunciator lights up, then you can turn the switch to the "OFF" position.

Andy

[choffmann]

Thanks Matt,
my question is possibly going a little further. Please let me clarify it: Is the switch spring-loaded, so it will move to the "off" position by itself when one of the disarm criteria (e.g. tipping the toe brakes) is met?
(Maybe I´m holier than the pope, here. LOL)

Chris

[choffmann]

Hi Andy,

so when does the pilot set the switch to "off" after landing? Especially when a high-speed turn-off from the runway is done? In all videos I have seen from landings (on youtube etc.) I have never seen this action of someone switching it to off.

Thanks Chris

[ANDYSMITH]

Hi there, once you apply brakes and dissarm the autobrake you do not really need to do anything with the switch. If you selected autobrake "3" for example on approach, then you can leave it there because it has been electrically turned off when you apply brakes. Then before takeoff you will select "RTO". But taxiing in and back out to the runway the switch has no effect.

Andy

[JBaymore]

I think that the REAL question here is....... "Does the physical dial on the physical switch move of its own accord when the autobrake sets (automatically) to "off"?"

I don't know the answer in the real pit....... but I think I got the question right.

best,

..................john

[ANDYSMITH]

Hi again, The reason to turn the switch to OFF would be if you land with autobrake set and did not feel the need to add more braking, then the plane will come to a complete stop before the autobrakes will release. You do not need or want to do this. So when you have slowed down to taxi speed and want to turn off the runway you will either need to stomp the brake and spill everyones drinks or turn the switch to the OFF position.

does that make sense?

Andy

[ANDYSMITH]

No the switch does not move by itself, You have to turn it manually.

Andy

[tomenglish2000]

I thought it would be strange that the autobrakes switch doesnt return to OFF from RTO or to DISARM from an autobrake level selection when autobrakes are overridden. The autobrakes on the 747, 757, 767 and 777 do it. So I went to good old YouTube and looked at
http://www.youtube.com/watch?v=8YIyyuv7jI0
and this
http://www.youtube.com/watch?v=eoVw18J_uEc
both of which show that the switch doesnt move on its own.

Tom.