Autobrakes

[FlyaGuppy]

I'm curious, how often do various carriers use autobrakes (either on landing or in RTO mode)?

I was told in 737 training that most pilots choose to not use them, to have more control over the aircraft in a RTO and during landing. True?

[Intruder]

In our 747s we arm them every flight for RTO and use them alomst every flight for landing.

[Flight Detent]

Except --- INTRUDER,

if you need to keep the brake temperatures down, then you would be prudent to turn OFF the auto-brakes, and use manual braking, as you come out of a quickly initiated engine reverser sequence -- works SO MUCH better as far as brake temps go!

Cheers

[Fresca]

When I was on the 737 we usually opted not to use them for landing but ALWAYS in RTO before T/O. The reason we didn't use them for landing is due to brake heating as the 737 we use uses steal brakes, and they tend to heat alot. On the other hand on the 757 (carbon brakes) we tend to use them most of the time.

[Track]

We always use RTO autobrakes, you can't beat RTO mode in terms of reaction time and performance. For landing on long runways I sometimes keep them off, on short rwy's we use them for minimum stop distance. That means selected on MAX so that it starts braking right after touchdown and then as soon as possible we override them manually for maximum deceleration.

For reference we recently used MAX autobraking up until full stop on a 1390 mtr runway (B737-700). No control problems whatsoever but very uncomfortable....

[xpc]

we use RTO for all takeoffs and autobrakes 2 for most landings autobrakes 3 for wet or max braking for wet landing heavy landing weight short rwy.

[Intruder]

Flight Detent:

I don't think so...

At least on the -400, Autobrakes set at 2 or 3, plus use of reverse thrust, plus judicious use of manual override of the brakes, will yield the lowest brake temps.

The -200 side of our fleet is the part that may opt out on Autobrakes for landing.

[john_tullamarine]

Another consideration relates to LVPs ... the use of autobrake greatly simplifies the pilot's workload in maintaining centreline during either RTO or landing if the visibility dies .... in a recent contract during sim training for LVP ops, I had pilots doing raw data handflown ILS to a stop in 0/0 for stick and rudder practice ... not too much trouble with autobrake on ... but much more demanding using manual braking due to the very fine localiser tracking needed to maintain a reasonable centreline ...

[18-Wheeler]

Have to agree with both Flight Detent and Intruder.
With the steel brakes, they get heated for a few seconds between touchdown and when the reverse thrust is fully established.
That's what he's inferring, and he's right, I've seen it a few times. If you leave the autobrakes off you can stomp on the brakes all you like below ~80kts and they just don't get hot.
Not experienced with carbon brakes, but I know from motorsport experience that if you use them, they're best gotten hot to reduce wear. They're relatively insensitive to heat. So I guess in that case you're best to give them that initial heating to get the temps up a bit.

[Cornish Jack]

Just a point re. mixing auto-brake and reverse thrust on carbon brakes - if reverse is used at anything above idle it can lead to excessive brake wear. Auto-brake looks at total retardation values and, if reverse is effective, it will modulate the brakes to maintain the selected rate. Modulating carbon brakes leads to extra wear - they're better on single application held on, to get the temperature up and keep it stable. For carbons, medium auto-brake with idle reverse seems to give the best results - assuming no runway limitations, of course!! :)

[Flight Detent]

Thanks -- "18-Wheeler" - obvious, I thought!

email me!

Cheers

[Intruder]

Cornish Jack:

Our 744 FHB recommends against using the combination of Autobrakes 1 and full reverse for that reason. Where there is a long runway and we want to roll to the end for a shorter taxi, we will sometimes use Autobrakes 1 and idle- or partial reverse.

[PPRuNe Towers]

There's a little known Boeing chart that offers dial-an-autobrake settings for distance to turn off. I've got one for the 737-300 and very lovely it is too:D :D

I know , I know - it would ruin someone's career enhancing memo writing on standardising a single autobrake setting for good little robots everywhere.

[maxy101]

I gather it may also depend on what type of maintainance contract Flt Ops has with the brake servicing company. In Big Airways we had a memo telling us to thrash the arse of the brakes for a while 'cos we were sending the brakes back virtually new.

[HPSOV]

Where I fly...
RTO is always used.
(I agree with this, as I cant think of a situation where you wouldn't want maximum possible braking as soon as possible?)

On landing we must use autobrakes unless they are U/S.
Normal setting would be 1-3 depending on desired taxiway exit, or runway lenght (we're having to use 4 on the Narita B runway).
(I feel that the captain SHOULD be allowed to perform manual braking if he desires.)

Full reverse thrust is the standard procedure, however this does not preclude the captain from electing to use idle reverse (this is only done if rolling through to the end of the runway).

This info for 767/2/3.
(762 with steel brakes, and 763 with Bugatti Carbon Brakes).