American 767 RTO at ORD
- Thread starter Colin Levy
- Start date
I'm not sure what you're asking.
Rotate at the last minute remaining, using the entire runway?
Use all remaining runway during a rejected takeoff?
Compute the takeoff distance using the full runway length and no intersection departures?
I think he means the last one? Making the takeoff from the beginning of the runway. That's just how it comes across to me.
Ok. Thanks!
In all of the transport category aircraft I've flown, once you abort, you're getting stopped ASAP because all of your numbers are based off of that, not a smooth roll to the end.
Plus, if you're on fire or something is really nasty going on. You want to get stopped, assess the situation and bounce out if you have to. And if you're on fire, airplanes burn very fast, especially with an engine fire and a crosswind so your options become severely limited with catlike quickness.
That's what we were talking about here, having extra runway in front of you so you don't have to burn up the brakes to an absolute stop or use up the built-in pad in the numbers, if something on the abort isn't going exactly as planned; rather than rolling off the end. An intersection takeoff, with runway left behind, leave useless runway behind. Operational need? potentially. Worth the risk? Depends. thousands of feet of runway still left in front of you after leaving some behind? Sure. Risk fairly negated. Just enough runway left to make the numbers? May or may not be worth it.
Like I said before, just interesting food for thought. If the numbers check, the numbers check, at the end of the day.
Nothing more useless than runway behind you!
But intersection takeoffs are heavily common on the civilian side, but it's not to the level that we'd do in the Cessnas (like midfield)
Agreed. And those were good points made.
Plus, something else to think about, if they autobrakes stay on, it'll get stopped. Set the parking brake, assess the situation and start doin' captain stuff. The brake temps and keeping it smooth for grandma and grandpa are so outside of my concern.
The quicker and more stable it starts, I can roll through the post rejected takeoff considerations about do we need to get out, say onboard, assess, wait, just 'what'.
The quicker and more stable it starts, I can roll through the post rejected takeoff considerations about do we need to get out, say onboard, assess, wait, just 'what'.
True. At the same time, taking care of the jet just a bit, if there's excess runway available and if the emergency allows, in order to not create another emergency in the process such as tires/brake pieces blowing out and that FOD causing other problems such as fuel leaks or structural damage, is nice....again, pending time/runway/emergency at hand allows it. If it doesn't, then you do what you have to do, any way you need to do it.
Of course, if the emergency you're aborting for is bad enough, none of that may make any difference anyway, and stopping it forthwith would be most prudent.
It's definitely good tabletop discussion and PhD-level thought.
amorris311
Well-Known Member
I am pretty positive part of the certification process for new transport category airplanes deals with every scenario you've listed. I just flew with a guy who was/is part of the certification process for the 737 MAX. They file down the brakes to the least allowable level, racing flat tires, some sort of contaminate on the runway, and max takeoff weight. They run a whole host of tests and collect data. I know you don't have the daily experience of flying transport aircraft but as others have mentioned the numbers are padded along with reaction times factored in.
Good questions nonetheless and it's interesting to see different perspectives. I'd be more interested to see what others think about landing runways. There are a few strips at certain airports we have numbers for but you better be on your game for it all to work and leave yourself an out.
And as mentioned before, there may not even be realization of the true extent of the situation at hand.
Which is why taking a dying jet in the air is a such scary proposition, as the crew may not even realize they may be taking off to their death. Crap situation all around, sadly.
I vaguely remember the 777 certing with abort factors and the like. Lots of various scenarios like you mention here, that were tested.
Yes, it's great discussion of various factors and the like. No one is doing anything wrong or mentioning anything that's unsafe; there's just different techniques that encompass different considerations.
Good talk all around. Good learning.
mastermags
Well-Known Member *giggity*
While that makes sense, no performance calculations or abort procedures account for pilot discretion in the strength of brake application. Its autobrakes max on most planes, and procedure calls for max braking until a complete stop. As far as fire, that pretty much depends on weight and speed of which the brakes are applied so 20000 feet of runway remaining shouldnt even figure into the procedure.
Agreed. With the autobrakes, its going to max until a stop per the procedure. So that takes care of that.
The runway remaining deal is a pad for if the RTO doesn't go exactly as planned.....maybe autobrakes don't work due to tire/brake damage from a blowout, etc. It may buy you something for a late reaction to a high speed RTO also.
Is it a need to have? No. Is it a nice to have? I'd like it if I had it. Does it change the procedure? No.
The NASA guys at RIV chose to roll out with their excess runway to a nice stop, and the plane still got destroyed. So, even that mileage varies. Agreed, getting the jet stopped is the main concern, and having one procedure to do that, simplifies standardization.
But again, all valid points you make.
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Just a side note, but full manual braking is actually a stronger application of brakes compared to auto brakes.
But the autobrake computer is way faster to recognize the "Rube Goldberg" series of machinations taking place during an RTO to begin the application process.
But the autobrake computer is way faster to recognize the "Rube Goldberg" series of machinations taking place during an RTO to begin the application process.
Interesting. Didn't know that. Is that particular to Airbus, or standard to Boeing models too?
amorris311
Well-Known Member
I believe all models that have autobrakes are that way. If I was a super pilot I would dig into my manuals and figure out the coefficient for braking, but I'm no super pilot.
As @Derg said the RTO setting recognizes to brake must faster than a human. Once you override it the manual pressure is greater but the half second it starts the process of slowing down could be life or death. Also I believe the RTO demonstration for verification uses half of the available brakes.
Thank you for the information. Indeed very interesting. Is that something with the newer models of aircraft, or is it something standard or retrofitted to older types like MD80, etc?
