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Parking Brake Post RTO

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Parking Brake Post RTO

Old 18th Sep 2021, 02:38
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Parking Brake Post RTO

Why does Boeing recommend not setting the parking brake following a RTO, whereas Airbus mandates it ? (Assuming they both are using carbon brakes)
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Old 18th Sep 2021, 04:22
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PRK BRK ..... PREFER CHOCKS?


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Old 18th Sep 2021, 13:34
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Pure philosophy I guess. Boeing does not want to exclude vacating the runway. Only if evacuation would be required, setting the parking brake is required and hence it became part of the evacuation checklist and not the RTO procedure. Same for the speedbrakes and flaps ie. Speedbrakes out is RTO requirement. Speedbrakes back in is either runway vacated normal procedure or part of evacuation procedure.
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Old 18th Sep 2021, 16:23
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From what I recall (from my distant past), the B737 (Classic) doesn’t have brake fans whereas the A320 does. Maybe something to do with HOT brakes and possible fire after an RTO?
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Old 18th Sep 2021, 18:13
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Probably not as the idea is common on 737 and 777, and Im guess other types have the same idea. Its clearly stated in the QRH of 737 and 777, independent of type of brakes: "consider not setting parking brake unless passenger evacuation is necessary"
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Old 18th Sep 2021, 19:50
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Ive always scratched my head a bit at that one: if the engines are running, then unless you are on the brakes or set the parking brake, which really amounts to the same thing, the aircraft might set off again down the runway (almost a certainty in the 777). Is that helpful while youre trying to figure out what went wrong and what to do about it?

Our SOP is to set the PB. You can always take it off and taxi away if it becomes the best course of action.
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Old 18th Sep 2021, 20:44
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Same. Parking brake set for all RTOs here. Airplane could move under certain conditions (slope, weight, surface condition) or you just happen to be flying an airplane with incredibly high idle (737 MAX) that moves under idle thrust at most weights.

Get the airplane stopped, prevent it from moving, focus on identifying and solving the problem and only then consider releasing the parking brake. Last thing I want following an RTO, is to keep looking outside if the airplane is moving or not.
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Old 18th Sep 2021, 21:36
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Habitually setting the parking brake with the brakes still being hot and keeping it engaged for longer than until the chocks have been insterted results in degradation of some components, e.g. seals. Not really your primary concern if you are in a rejected takeoff situation with the possibility of evacuation right after. You should be more concerned with keeping the aircraft stationary (and in some airframe-engine combinations, e.g. A320F with IAE V2500 engines, it's certain that the aircraft will start rolling the moment you release the brakes).
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Old 18th Sep 2021, 23:12
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A lot of years ago when I did my B707 training I was told not to set the park brake after an RTO in case the brakes welded together and then the aeroplane could not be moved clear of the runway after all the fuss was over without a lot of wheel changes.

To stop the thing rolling I was instructed to turn into wind as you stopped then just as you came to a complete stop turn the tiller to full lock and with the nosewheel at full travel there was very little chance that the aeroplane would roll anywhere.
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Old 18th Sep 2021, 23:54
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787 QRH RTOW procedure.

When the airplane is stopped, perform procedures as needed.

Review Brake Cooling Schedule for brake cooling time and precautions (refer to the Performance Inflight chapter).

Consider the following:

the possibility of wheel fuse plugs melting

the need to clear the runway

the requirement for remote parking

wind direction in case of fire

alerting fire equipment

not setting the parking brake unless passenger evacuation is needed

advising the ground crew of the hot brake hazard

advising passengers of the need to remain seated or evacuate

completion of Non-Normal checklist (if appropriate) for conditions which caused the RTO
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Old 19th Sep 2021, 08:28
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Originally Posted by FlyingStone View Post
Get the airplane stopped, prevent it from moving, focus on identifying and solving the problem and only then consider releasing the parking brake. Last thing I want following an RTO, is to keep looking outside if the airplane is moving or not.
Again, Boeing does not stop you from doing so if you think that's the safer option. The wording is different, the wording is "consider not setting unless evacuation".

Not saying right or wrong here, but I think many are "sim biased" in my opinion.

Reality is that 100% of all rejects I have done, I have never set the parking brake because they were either low speed or there was not a problem that might require an evacuation. So it's pretty realistic to have the idea not to set the parking brake but vacate the runway and then if necessary stop on the taxiway to take care of the problem. Which is what I've done on 100% of the rejects in my life.

If there's a possible need to evacuate, the need will be clear at the moment you initiate the reject and Boeing does not stop you from setting the parking brake. If you make the parking brake part of the RTO procedure, it becomes mandatory for every reject, disregarding the cause of the RTO. So I prefer this Boeing extra "freedom" as opposed to the mandatory "Airbus".

With sim biased I mean sims are always worst case. And yes it's sound to set the parking brake and in many times you will already have the evacuation checklist ready on your lap (at least we have). But even then Boeing says not to rush so there is time to set the parking brake and move on to the evacuation checklist. Which is also the reason why the evacuation checklist was moved from pure memory to read and do. Don't rush but be mindfull of every step you do.

Last edited by BraceBrace; 19th Sep 2021 at 08:44.
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Old 19th Sep 2021, 08:57
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I'm lost. If you don't set the parking brake, how do you stop the aircraft from rolling away whilst you are neck deep in dealing with the problem?
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Old 19th Sep 2021, 09:19
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Because nine times out of ten you aren’t neck deep in a problem. Most aborts are simple things, like a suspected runway incursion, or ATC instruction at low speed, birds on the runway etc etc
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Old 19th Sep 2021, 12:43
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When setting the parking brake once stationary, does this count as an application and increase the brake temperature further? Would be nice to clarify.
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Old 19th Sep 2021, 13:38
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Quite simply after a RTO the brakes will be very hot.

So leaving the brakes released aids airflow and cooling and reduces the risk of the fusable plugs blowing and of the brakes ceasing on and allows the aircraft to be moved, which is less important.

Putting the parking brake on reduces risks of the aircraft moving and injury during evacuation, rescue crews etc, and makes it easier and safer for the rescue crew to enter. It closes the drill neatly so the pilots can vacate the a/c and close the actions list in other circumstances.

Back in the day it was the advice of some OEMs to continue taxying after a RTO to aid wheel cooling and prevent the brakes fusing.
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Old 19th Sep 2021, 18:08
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Checkboard

I think perhaps I was a bit subtle. Either you want to be stationary or you want to be moving. If you decide to come to a complete stop, you have to prevent the aircraft from further movement. Either hold it on the brakes or apply the park brake - from a brake temperature point of view I doubt there is any difference, in which case you might as well apply the park brake.
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Old 19th Sep 2021, 19:51
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Also, if you dont override the AB system during deceleration, AFAIK maximum brake pressure will continue to be applied even after you have come to a halt, having the same effect as a set PB. The difference is that if it subsequently disarms for any reason and you dont notice, you might start moving unintentionally, so deliberately applying the PB makes no difference to temperatures, etc. but protects you from that scenario.

Unless the cause of the RTO is immediately obvious and carries no particular adverse effects, even at low speed my plan would be bring the aircraft to a fairly rapid stop on the runway and make a thorough assessment. There have been numerous cases of severe failures where there has been little or no flight deck indication of a problem but a catastrophic time-critical event has begun. 737 at Manchester and 777 at Vegas come to mind straight away...
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Old 19th Sep 2021, 23:07
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Having seen some operators do some horrible things with braking after landing - and the associated brake temperatures increasing during taxi in - I am convinced there is no way brakes could bind in the two minutes or so it would take to decide if a vacate or an evac is the next step after questionably the "worst case" RTO - high speed, max weight, runway limited, Engine Fire indication that doesn't go out.
From that it was always my intention that should a RTO occur on line once fully stopped I would park the brake.

Interesting that most times we are to "sit on our hands" and make sure about identifying problems correctly yet during an RTO we are "expected" to immediately decide whether an evac may be required - surely the priority should be to ensure a successful RTO (arguably one of the most/more stuffed up exercises in the SIM by all accounts), correctly assess and identify the problem then act accordingly.

Negative training IMHO, as open to personal interpretation greatest "threat" was to make sure in the SIM you did what the checker expected/would accept simply to get the tick in the box and get the hell out of there.
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Old 20th Sep 2021, 07:51
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FullWings

Interesting as both cases had fire warnings. In the case of the BA 777, it was hardly a "high speed" reject, I believe they did not even reach 80kts. Yet the crew got so hyperfocused on procedures, none of the 3 crewmembers on the flightdeck heard the cabin trying to call them. Very good "situational awareness".

Again, SOP's are never bullet proof as we are all human. It is an balancing act between focus and time spent to do an action deliberately, and time lost to do something else. They are nice up to the moment we realise that we are under stress and then the confusion begins and precious time is lost like crazy. Boeing has realised this, there is no need for a "military war zone" approach (which is where all the memory items come from) and Boeing has slowly begun changing many many memory items to "non-memory items" and is continuing to do so even today with the go-around call changes (the call makes you focus on flap, an SOP that created an unwanted side effect we focus less on thrust setting)

The autothrottle disconnect is the most fantastic example. AT disconnect IS a necessity, hence an SOP, but it shows how human we all are. The big fun begins when you give a fire warning at 40kts, or even at 10 kts with the engines spooling up to TO power, FO PF and his hands on the throttles. You can discuss parking brakes as much as you like, add it to the procedures, memory items...

So be carefull when you want to put something in an SOP. It's a "be carefull what you wish for" situation. You can make as many SOP's as possible, it won't help you a single thing if you don't teach people to take a distance from the situation. Because the adrenaline will get you and everybody reacts differently. Look at the BA Vegas incident.

And if all goes well and you want to set the parking brake, who cares, go for it. Who stopped you? The fact it's not an SOP? How is that possible?

If the SOP says to drink your coffee before TOD, you will have to drink it despite of the served temperature. If the SOP says nothing about coffee, drink freely at required temperature, or throw it away if you don't like it. Or get a second one. Or tea. Or water.

Last edited by BraceBrace; 20th Sep 2021 at 08:03.
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Old 20th Sep 2021, 08:03
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make sure in the SIM you did what the checker expected/would accept simply to get the tick in the box and
I cringe at such statements, but this and the supporting views are realistic.
galdian (BraceBrace similar)

Most situations in aviation - in life, depend on context; on how we interpret the immediate situation, and that this will not be the same as in the simulator (its only a simulation - not real), and its unlikely that the required action will be as in the book.

I do not know why Airbus differs from Boeing, possibly differences in philosophy.
Airbus considers design and technology to protect pilots from themselves, with margin to think. Boeing allows pilots to choose to do (to think) as they wish, then controls with procedures and rules.

The important issue is to think about the situation before it arrises - consider the context, safety priorities, required outcome. At least you will have a basis for defence, but don't expect anything better than a draw from discussions with the Chief Pilot, Training Capt, or anything which is written, which is never as in real situations.

Re the opening question, don't expect an answer, only opinion; think for yourself beforehand because its your opinion which is important, on that day, in a real situation.
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