Well that's embarassing

[petrolero]

The departure runway is selected in the FMS as part of the FMS initialization process.


That happens all the time. Almost all departures from EWR, and most from ORD, for example, are intersection departures. It's very common.

What happened, as I understand it, is that there was a small change in the available length of the runway due to some construction at the approach-end. This was indicated in the performance data with a code to distinguish it from data for the normal distance for that runway. Unfortunately, the code used was similar to an intersection name much farther down the runway and the crew made the mistake of thinking that the data was for a departure from that intersection.

But the airplane let itself accelerate to 100 mph (says the report) before determining that it couldn't pull this off? Why even start the roll? Why not give some warning?

"I wouldn't do that if I were you, Dave."

Anyway at least HAL 9000 didn't fly them into the trees again.

 

[Greg Bockelman]

But the airplane let itself accelerate to 100 mph (says the report) before determining that it couldn't pull this off? Why even start the roll? Why not give some warning?

"I wouldn't do that if I were you, Dave."

Anyway at least HAL 9000 didn't fly them into the trees again.

I think we are confusing two different incidents here. One is a 777 incident and one is the 350 incident that this thread is about. I think Larry is talking about the 777 incident.

If you are talking about the 350 incident, the airplane didn't LET itself do anything. As of right now, we have no idea why the 350 CREW decided to abort the takeoff. But until proven otherwise, I am convinced that the airplane did not do anything by itself.

 

[Lindberg]

I think we are confusing two different incidents here. One is a 777 incident and one is the 350 incident that this thread is about. I think Larry is talking about the 777 incident.

If you are talking about the 350 incident, the airplane didn't LET itself do anything. As of right now, we have no idea why the 350 CREW decided to abort the takeoff. But until proven otherwise, I am convinced that the airplane did not do anything by itself.

This seems to contradict the alleged statement by the Airbus representative on board the plane.

 

[fiveoboy01]

Yeah but that's assuming that his statement was accurately conveyed by media... Which doesn't always happen.

Isn't there autobraking when a RTO sequence is initiated by the crew? Maybe that's where the confusion lies.

 

[Henning]

That they did.

I was about to say Miami shouldn't pose anyone a problem.

 

[Henning]

I think we are confusing two different incidents here. One is a 777 incident and one is the 350 incident that this thread is about. I think Larry is talking about the 777 incident.

If you are talking about the 350 incident, the airplane didn't LET itself do anything. As of right now, we have no idea why the 350 CREW decided to abort the takeoff. But until proven otherwise, I am convinced that the airplane did not do anything by itself.

Ahhh! So you think the entire auto shut down premis is false, interesting.

 

[Henning]

This seems to contradict the alleged statement by the Airbus representative on board the plane.

As reported by a travel corespondent, not an aviation correspondent, and perhaps not accurate when delivered by the management PR rep trying to apply spin control.

 

[Greg Bockelman]

Yeah but that's assuming that his statement was accurately conveyed by media... Which doesn't always happen.

Isn't there autobraking when a RTO sequence is initiated by the crew? Maybe that's where the confusion lies.

To the first statement - That is my bet. I don't trust the media to report anything accurately.

To the second - That is exactly right. That is what I think the Airbus "representative" was referring to.

 

[Henning]

Yeah but that's assuming that his statement was accurately conveyed by media... Which doesn't always happen.

Isn't there autobraking when a RTO sequence is initiated by the crew? Maybe that's where the confusion lies.

It would make a lot more sense that way.

 

[Henning]

To the first statement - That is my bet. I don't trust the media to report anything accurately.

To the second - That is exactly right. That is what I think the Airbus "representative" was referring to.

It wasn't even the Airbus rep, it was the Quatar Airlines rep which makes it even more likely, "Wasn't out fault, it was the plane."...

 

[Greg Bockelman]

Ahhh! So you think the entire auto shut down premis is false, interesting.

Yes I do. When the crew initiates a rejected takeoff above a certain speed the auto rake system automatically applies maximum braking effort to bring the airplane to a stop. I am reasonably sure that is what the representative was referring to.

 

[Henning]

Yes I do. When the crew initiates a rejected takeoff above a certain speed the auto rake system automatically applies maximum braking effort to bring the airplane to a stop. I am reasonably sure that is what the representative was referring to.

It sure as hell makes more sense. I had never heard of a plane that auto rejected a take off, but since it's a new release, I was unsure.

 

[Everskyward]

To the first statement - That is my bet. I don't trust the media to report anything accurately.

To the second - That is exactly right. That is what I think the Airbus "representative" was referring to.

Not only that, it says here that...

A passenger reported they were told the aircraft applied auto brakes due to a signal the runway was too short for their takeoff.

I wouldn't put much faith in what "a passenger reported".

http://avherald.com/h?article=490a76a2&opt=0

 

[Henning]

Not only that, it says here that...

I wouldn't put much faith in what "a passenger reported".

http://avherald.com/h?article=490a76a2&opt=0

It makes sense really if you read that as, "An annunciator light came on with a runway performance warning and the pilots hit the RTO button which activated the automated abort sequence bringing the plane to a safe stop."

That doesn't generate many clicks though.

 

[Greg Bockelman]

No RTO button. It is automatic with a reduction in power above a certain wheel speed.

 

[Fearless Tower]

It wasn't even the Airbus rep, it was the Quatar Airlines rep which makes it even more likely, "Wasn't out fault, it was the plane."...

Not surprising. Qatar is a crack pot outfit. The CEO is a nut case. Tried to blame the 777 MIami incident on ATC.

 

[Henning]

No RTO button. It is automatic with a reduction in power above a certain wheel speed.

Got it, so just chop the throttles, and it manages best rates from there?

 

[Henning]

Not surprising. Qatar is a crack pot outfit. The CEO is a nut case. Tried to blame the 777 MIami incident on ATC.

Please don't get upset if I fail to be surprised. I'm not in Dubai working for a reason, rich Arabs are freaking nuts. It's like what you get if you take the Jersey Shore crowd and give them all $250,000,000 with 1 in 20 jack pot winners of $2,500,000,000.

 

[Fearless Tower]

Please don't get upset if I fail to be surprised. I'm not in Dubai working for a reason, rich Arabs are freaking nuts. It's like what you get if you take the Jersey Shore crowd and give them all $250,000,000 with 1 in 20 jack pot winners of $2,500,000,000.

I'm not terribly surprised myself. I only bring up the 777 incident as evidence that this is far more likely to be an operator problem than an airplane problem.

 

[Henning]

I'm not terribly surprised myself. I only bring up the 777 incident as evidence that this is far more likely to be an operator problem than an airplane problem.

I would not be surprised in the slightest, Arab culture makes training privileged Arabs challenging, and airline pilot is a still a position of privilege in Arab culture; a cool and desirable job. Teaching them to dock their 105' Leopard or Mangusta with 3800hp engines and Arneson drives can leave one exasperated.

 

[petrolero]

I think we are confusing two different incidents here. One is a 777 incident and one is the 350 incident that this thread is about. I think Larry is talking about the 777 incident.

If you are talking about the 350 incident, the airplane didn't LET itself do anything. As of right now, we have no idea why the 350 CREW decided to abort the takeoff. But until proven otherwise, I am convinced that the airplane did not do anything by itself.

I'm not referring to any 777 accident.

I'm referring to today's incident which was described above by an airbus rep someone (paraphrasing) as the aircraft's computer's having (apparently autonomously) rejected the takeoff after reaching "100 mph" due to an incorrectly identified intersection or available runway length.

The HAL 9000 snark was in reference to this infamous Airbus crash in 1988 at the airshow in France.

The idea that the aircraft would begin the takeoff roll when there wasn't enough runway seemed fishy.
https://www.youtube.com/watch?v=OGHVnIxNUIw

 

[Greg Bockelman]

Got it, so just chop the throttles, and it manages best rates from there?

Yes. Maximum braking.

 

[Larry in TN]

Got it, so just chop the throttles, and it manages best rates from there?

Not sure what you mean by 'best rates'.

I've never flown an Airbus but the RTO function should be similar to the Boeings I've flown.

On the Boeings, you set the autobrakes to RTO prior to the takeoff. At about 80 knots on takeoff the RTO mode is armed. If the thrust levers are brought back to idle after that point the autobrakes apply max anti-skid braking and will bring the airplane to a full stop if no other action is taken.

The RTO procedure is for the Captain to bring the thrust levers to idle, verify that autobrakes are operating and, if not, apply max manual braking, extend the speed brakes, then apply max reverse thrust. The F/O makes note of the max ground-speed achieved, verifies the RTO braking, speed brake extension, and thrust reverser activation, then notifies the tower of the rejected takeoff.

The only thing that is automatic is the application of max anti-skid braking.

Once stopped the OAT, weight, and max ground speed is used to determine the brake energy which defines the risk of tire failure/brake fire. If the brake energy was low, and the problem that caused the reject is corrected, another takeoff can be accomplished without returning to the gate. If the brake energy is high(er) then you wait a specified amount of time (the heat peaks 5-15 minutes after the reject) then inspect the tires to ensure that the fuse plugs have not melted. The inspection is not time consuming but you must wait the specified amount of time to allow the fuse plugs to melt if they are going to melt.

As far as the reports of an "auto abort"... Airbus has developed some warning systems which look ahead at the runway available and these systems are on the A350. I have no idea of the specifics of what these systems monitor, when they monitor it, and what they do when their tolerances are exceeded. I would expect just an audible warning but I don't have any information on what it does. Perhaps a false alarm from such a system resulting in a pilot-initiated rejected takeoff? I don't know.

 

[Henning]

Best rates means it gives it everything it can without breaking, burning, locking... components. Big masses need at least some level of finesse to slow rapidly no matter how well built, especially when trying to keep them light. They were likely carrying a full load of fuel, they were heavy.

 

[iWantWings]

The plane didn't think 11,000 feet was enough runway.

https://www.yahoo.com/travel/fail-first-us-flight-of-fancy-new-airbus-jet-171400857.html

Why would the automated system decide the runway is too short only after it was already rolling on the runway for takeoff? (I read some of the comments but not all, so sorry if this was already answered).

Good thing the aircraft does not auto taxi cuz who knows what it might do next

(EDIT: I'm trying to imagine the pilots' surprise when that massive plane begins screeching to halt - uncommanded (at least not by the pilots))
(EDIT2: okay, so I read that it's possible the "runway too short" report in the yahoo article might not be correct, and that the automatically-aborted takeoff roll could have been for a different reason; that would make more sense)

 

[Larry in TN]

Best rates means it gives it everything it can without breaking, burning, locking... components.

As has been described already, that is not what the RTO brakes do. RTO braking is max anti-skid braking without regard for breaking, burning locking, etc. components. Post-reject brake fires and tire failures are an expected result when the brake energy is high enough.

 

[Sluggo63]

Best rates means it gives it everything it can without breaking, burning, locking... components. Big masses need at least some level of finesse to slow rapidly no matter how well built, especially when trying to keep them light. They were likely carrying a full load of fuel, they were heavy.

Usually (like stated above) the RTO function of the autobrakes will give maximum braking after certain conditions are met (system armed, above 85 kts, throttles retarded to idle). There is no rate but maximum and you will probably break something, and heavy weight and high speed, you will catch fire after about 10-15 minutes.

Where there is a rate component, is typically on landing autobrake selection. In my aircraft, we can choose AUTOBRAKES 1, 2, 3, 4, or MAX AUTO. These selections are rate sensitive, meaning whatever you select corresponds to a deceleration rate and the brakes will modulate pressure to give you that selected rate. I don't know the numbers, but for instance, if the engineers determine that AUTOBRAKES 2 should result in a 5 m/s^2 deceleration, when you touch down the brakes will start adding pressure to get that deceleration. When you put out the thrust reversers, the brakes reduce pressure to maintain that 5 m/s^2 rate, although you are getting most of your slowing from the TRs. In fact, with a low AB setting and max reverse the brakes may not be working at all since you'll exceed the deceleration rate with reverse alone.

Maximum braking on landing is done with manual brakes for this reason (we'd use AB to begin the braking process, then stand on the pedals to get the maximum stopping effectiveness).

 

[Henning]

If that's the facts, then they should have had a gear fire if they used the auto system.

 

[Greg Bockelman]

Why would the automated system decide the runway is too short only after it was already rolling on the runway for takeoff? (I read some of the comments but not all, so sorry if this was already answered).

That is the $64 question. IF a system were designed to do what is described, then is sure would know before it started rolling.

But since there is no system that will autonomously reject a takeoff, it is kind of a moot point.

 

[Greg Bockelman]

If that's the facts, then they should have had a gear fire if they used the auto system.

Not necessarily. It depends on how fast they were going and how heavy they were at the point that the takeoff was rejected. At max gross weight, if the RTO occurred just prior to V1, then you almost certainly will have the brakes catch fire. But in this case, since they weren't much past the RTO arming speed, there probably wasn't enough energy dissipated into the brakes to get them that hot. That is why there are brake cooling times in the event of an RTO.

 

[Henning]

Not necessarily. It depends on how fast they were going and how heavy they were at the point that the takeoff was rejected. At max gross weight, if the RTO occurred just prior to V1, then you almost certainly will have the brakes catch fire. But in this case, since they weren't much past the RTO arming speed, there probably wasn't enough energy dissipated into the brakes to get them that hot. That is why there are brake cooling times in the event of an RTO.

I wouldn't think they would be light taking off and heading for Quatar, good thing they were slow then.

 

[Greg Bockelman]

There is no rate but maximum and you will probably break something,

I don't necessarily agree with that, unless you mean potentially melting the fuse plugs and/or catching the brakes and tires on fire.

and heavy weight and high speed, you will catch fire after about 10-15 minutes.

I might have to disagree with that just a bit. To get certified, the aircraft must sustain a brake fire for 15 minutes before any major damage is sustained to the rest of the air frame. Not that it can't start burning for 15 minutes. I suspect that is to ensure that the CFR people can get to the airplane before it turns into a conflagration.

 

[Sluggo63]

I don't necessarily agree with that, unless you mean potentially melting the fuse plugs and/or catching the brakes and tires on fire.

That's what I meant...

I might have to disagree with that just a bit. To get certified, the aircraft must sustain a brake fire for 15 minutes before any major damage is sustained to the rest of the air frame. Not that it can't start burning for 15 minutes. I suspect that is to ensure that the CFR people can get to the airplane before it turns into a conflagration.

What I was trying to convey is that it takes about 10 minutes for the brakes to reach maximum temperatures after the stop. Sure a heavy-weight, high-speed reject can cause a brake fire earlier than that, but just because the brakes aren't on fire when you stop, doesn't mean they won't catch fire 10 minutes later when the temperatures peak.

 

[Henning]

That's what I meant...



What I was trying to convey is that it takes about 10 minutes for the brakes to reach maximum temperatures after the stop. Sure a heavy-weight, high-speed reject can cause a brake fire earlier than that, but just because the brakes aren't on fire when you stop, doesn't mean they won't catch fire 10 minutes later when the temperatures peak.

Well, technically temp peaked when the plane stopped and energy quit being added. It just may take 10 more minutes for the heat to spread to where it can catch something on fire.

 

[Busflyer]

Well, technically temp peaked when the plane stopped and energy quit being added. It just may take 10 more minutes for the heat to spread to where it can catch something on fire.

No, that's not correct. The other posters are correct. Temperatures will peak 10-15 minutes after. You can watch the brake temps in the cockpit and they will continue to rise after we are parked at the gate.

 

[Henning]

No, that's not correct. The other posters are correct. Temperatures will peak 10-15 minutes after. You can watch the brake temps in the cockpit and they will continue to rise after we are parked at the gate.

Where does the energy come from? In order to raise temp, you have to add energy. When the plane has stopped, what adds that energy? The radiant surface expands and it can radiate more heat, but no heat is being added, and the peak local temp goes down from the stop on as it radiates out diluting peak.

 

[Matthew]

The temps at the sensor locations will continue to rise as the heat soaks in. I don't know if the sensors are mounted at the most temp critical point.

 

[Sluggo63]

Where does the energy come from? In order to raise temp, you have to add energy. When the plane has stopped, what adds that energy? The radiant surface expands and it can radiate more heat, but no heat is being added, and the peak local temp goes down from the stop on as it radiates out diluting peak.

I think the confusion lies in what we care about in the cockpit. True, after you stop, you aren't adding energy to the system, but we're worried about the temperature out where the Brake Temperature Monitors System (BTMS) sensors are. Out where the critical components are located like hydraulic lines, fuse plugs, etc. It's going to take about 10 minutes for the heat trapped in the center of the brakes to reach the BTMS sensors, and that's what we see in the cockpit.

 

[Henning]

Right, but that's a measuring issue like I pointed out, not a max temp issue. Max temp comes right around the point it stops as is shown, it just takes a while to spread to where it is measured, and where it does damage.

 

[Sluggo63]

Right, but that's a measuring issue like I pointed out, not a max temp issue. Max temp comes right around the point it stops as is shown, it just takes a while to spread to where it is measured, and where it does damage.

I agree.