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IanfromRussia
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Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 11:51 am

Hi! :)
As I have learned, Boeing manuals require manual extension of speedbrakes on RTO and stress the necessity of doing so despite they would extend automatically upon activation of the thrust reversers (I suspect, only if at least one of the TR is operative). I watched several videos with RTO drills in simulator, showing this procedure. But all these drills involved engine fire apparently without any thrust assimetry. In the case of a severe engine failure a strong yawing moment may arise abruptly and the pilot (assume for simplicity, that the captain is the PF) would struggle to regain directional control over the aircraft. After the throttles are slammed back, the pilot would have to level the pedals gradually, as the aircraft is brought back to the normal heading. It is stressed in all manuals and tutorials for pilots that keeping safe trajectory of the aircraft is paramount and has priority over any other action. Having not myself even a driver's license but understanding, as an aeronautical engineer, the physics of aircraft operations, my guess is that deploying the speedbrakes is essential to directional control, as they ensure good contact of the wheels with the runway, and must be done as quickly as possible while the pilot strives to recapture the directional control. But I have almost zero knowledge in psychological aspects of airmanship. So, what in opinion of the real 737 pilots is right: 1) to pull the speedbrakes handle immediately after slamming the throttles back (as it is done in drills I have watched) or 2) after slamming the throttles back the pilot must do anything only when he have fully recovered the correct heading of the aircraft?
 
Woodreau
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 1:03 pm

I cannot comment on the specific 737 procedures on rejecting a takeoff, I think the instructor would prefer the pilots to expeditiously retard the thrust levers to idle and deploy the speed brake rather than slamming the throttles back and pulling the speed brake handle.

There is no drama or struggle involved in operating an aircraft.

While rejecting a takeoff is not a common occurrence it is not beyond the capabilities of an average pilot that is demonstrated during their initial type certification and regularly during recurrent simulator training.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 2:48 pm

Woodreau wrote:
I cannot comment on the specific 737 procedures on rejecting a takeoff, I think the instructor would prefer the pilots to expeditiously retard the thrust levers to idle and deploy the speed brake rather than slamming the throttles back and pulling the speed brake handle.

What is the difference between "expeditiously retarding the thrust levers to idle" and "slamming the throttles back"?
 
GalaxyFlyer
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 3:04 pm

Airplanes are flown with pressures applied with fingertips, not fists slamming controls around, that’s the difference.

As the throttles are retarded, the handling pilot has to remove the rudder to avoid swerving into the applied rudder that isn’t opposing thrust any longer. It’s a coordinated action, not independent ones. Get the power off, plane straight, then deploy the stopping devices, speed brakes and wheel brakes.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 3:50 pm

GalaxyFlyer wrote:
Airplanes are flown with pressures applied with fingertips, not fists slamming controls around, that’s the difference.

As the throttles are retarded, the handling pilot has to remove the rudder to avoid swerving into the applied rudder that isn’t opposing thrust any longer. It’s a coordinated action, not independent ones. Get the power off, plane straight, then deploy the stopping devices, speed brakes and wheel brakes.

But the wheel brakes will be engaged automatically as soon as both tcls are at idle. Does this mean that one should be careful of keeping the engines above idle until the aircraft fully regains the right heading?
 
GalaxyFlyer
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 4:01 pm

No, just need to get the plane tracking straight. I was considering manual braking, RTO function will do its job while you do yours. If there’s an RTO function, it almost certainly has auto spoilers, the pilot is just backing up the auto function.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 4:08 pm

GalaxyFlyer wrote:
No, just need to get the plane tracking straight. I was considering manual braking, RTO function will do its job while you do yours. If there’s an RTO function, it almost certainly has auto spoilers, the pilot is just backing up the auto function.

So the pilot is likely to have the engines at idle before (or around the moment) he begins to recapture the course parallel to the centerline, and then he deploys speedbrakes and thrust reversers while steering the aircraft to the desired heading?
 
GalaxyFlyer
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 4:19 pm

Yup
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 4:26 pm

GalaxyFlyer wrote:
Yup

I. e. hands and legs doeing their respective jobs first in strict coordination and then independently?
 
bigb
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 7:29 pm

I can comment on the 737, but the 747 and I know 777. The speed brakes will auto deploy in the event of a RTO when the thrust levers reduced to idle and TR deployed to reverse Idle above 80 knots.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Fri Jan 21, 2022 8:20 pm

bigb wrote:
I can comment on the 737, but the 747 and I know 777. The speed brakes will auto deploy in the event of a RTO when the thrust levers reduced to idle and TR deployed to reverse Idle above 80 knots.

In 737 they are autodeployed upon engagement of thrust reversers above 80 knots, but Boeing insist that the only good practice is to deploy them manually. I suspect, that they don't consider the logic of their deployment to be reliable enough. 737 is exceedingly conservative airplane even by standards of 1960s. As far as I can remember, the thrust reversers are commanded mechanically and it is likely that You can't fully deflect the lever if the reverser is inoperative. As far as I have learned, normally both levers are used in the case of an RTO without caring to choose the correct. Than even is only one of Your reversers is inop, the blocked lever would prevent Your hand from raising the operative one. And it is legal per MEL to fly with the both thrust reversers inop. So it may be wise indeed to deploy the spoilers manually. The contribution of the thrust reversers to decelerating the aircraft is relatively modest and spoilers (speedbrakes) prevent the wing from generating lift and ensure good contact of the wheels with the ground which is not only the best way to decelerate but also is critical to the directional stability and controllability of the aircraft on the ground.
 
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Starlionblue
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Re: Use of speedbrakes in Boeing 737 during RTO

Sat Jan 22, 2022 4:29 am

Ianfromrussia, you seem very concerned about reaction times. In general terms, I would say that in an airliner it is typically better to take a bit longer making a decision than to rush things. An extra second or two, even in the case of a rejected takeoff decision, won't make a material difference.

Also, airliners are certified for controllability in abnormal situations. If a pilot of average skill cannot control the worst-case thrust asymmetry, the airliner would not be certified.

As mentioned above, controls are not "slammed", or "pulled". We use adequate force, which typically is not very much. Positive but delicate movements.

Side note: Airliners have thrust levers, not throttles.



I'll add that it doesn't matter if captain is PF for the sector. He is always PF in a rejected takeoff, even if the FO is PM for the sector. (The exception would be incapacitation.)

Once thrust is set, if the FO is PF, he will remove his hand from the thrust levers and the captain will place his hand on them. On some types and/or at some airlines, the captain also sets the takeoff thrust, so the FO never touches the thrust levers during takeoff.

If the captain decides to reject, he will call "STOP!". He also becomes PF if he was PM. On the 'bus, this is the only time a transfer of control happens without the phrase "I have control."
 
QF93
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Re: Use of speedbrakes in Boeing 737 during RTO

Sat Jan 22, 2022 10:50 am

Starlionblue wrote:
As mentioned above, controls are not "slammed", or "pulled". We use adequate force, which typically is not very much. Positive but delicate movements.

Side note: Airliners have thrust levers, not throttles.



Off topic but I never understood why footage from inside the Concorde cockpit showed the pilots quite literally slamming the thrust levers forward at commencement of takeoff roll, complete with a countdown.

If there are any Concorde experts lurking I would love to know the reason for the quite drastic slamming.
 
113312
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Re: Use of speedbrakes in Boeing 737 during RTO

Sat Jan 22, 2022 1:04 pm

The actions depend upon the model of 737 you are operating. Newer ones have autobrakes and autospoilers. Both will activate when the trust levers are retarded in a rejected takeoff. However, it is the pilots responsibility to follow up that the spoilers did deploy and that the aircraft is decelerating. Autobrakes in RTO mode should provide optimum braking all the way to a full stop. However, it is human instinct to apply manual brakes which will kick off the autobrake function. In the old days on 707s and 727s without these features, the drill was: thrust levers idle, apply maximum brakes, speed brake lever extend. This is done without delay. Yes, there is a directional control element in the case of loss of thrust in an engine. But not all rejected takeoffs are from an engine failure. Even when there is asymmetric trust, maintaining directional control should be an instinctive reaction of the pilot with the rudder and should not result in significant deviation on the runway.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Sat Jan 22, 2022 3:06 pm

Starlionblue wrote:
Ianfromrussia, you seem very concerned about reaction times. In general terms, I would say that in an airliner it is typically better to take a bit longer making a decision than to rush things. An extra second or two, even in the case of a rejected takeoff decision, won't make a material difference.

Also, airliners are certified for controllability in abnormal situations. If a pilot of average skill cannot control the worst-case thrust asymmetry, the airliner would not be certified.
"


Do You mean that if the aircraft suddenly begins to veer off the centerline of a wet 140 ft wide runway and full rudder deflection appears just a bit short of stopping it doing so than an extra second or two before beginning to retard the thrust levers won't make a material difference?

I understand well that the aircraft are designed to be controllable in abnormal situations by an average pilot (with certain caveats). I may seem to be concerned with reaction times but not in the sense of believing that they are inadequate. I only try to learn what course of action is proper to fully exploit the capabilities of the aircraft and of an average pilot in certain scenarios. To put it plainly, I try to learn how an RTO (especially a most challenging case) looks from the cockpit.
 
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Starlionblue
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Re: Use of speedbrakes in Boeing 737 during RTO

Sun Jan 23, 2022 12:58 am

IanfromRussia wrote:
Starlionblue wrote:
Ianfromrussia, you seem very concerned about reaction times. In general terms, I would say that in an airliner it is typically better to take a bit longer making a decision than to rush things. An extra second or two, even in the case of a rejected takeoff decision, won't make a material difference.

Also, airliners are certified for controllability in abnormal situations. If a pilot of average skill cannot control the worst-case thrust asymmetry, the airliner would not be certified.
"


Do You mean that if the aircraft suddenly begins to veer off the centerline of a wet 140 ft wide runway and full rudder deflection appears just a bit short of stopping it doing so than an extra second or two before beginning to retard the thrust levers won't make a material difference?

I understand well that the aircraft are designed to be controllable in abnormal situations by an average pilot (with certain caveats). I may seem to be concerned with reaction times but not in the sense of believing that they are inadequate. I only try to learn what course of action is proper to fully exploit the capabilities of the aircraft and of an average pilot in certain scenarios. To put it plainly, I try to learn how an RTO (especially a most challenging case) looks from the cockpit.


As 113312 says above, if the aircraft starts to veer off the centreline the PF will correct almost without conscious thought. There is no delay. For retarding thrust, there's already a one-second reaction time buffer. Additionally, the calculations have a safety factor. So yes, if you delay pulling the thrust levers to idle for a couple seconds, you should still be able to stop. Note that I'm not suggesting you wait just for the sake of it. But making an informed decision, as much as the circumstances allow, is better than performing a high speed reject for a spurious reason.

There are numerous rejected takeoff videos from sim sessions on Youtube. https://www.youtube.com/results?search_ ... ff+cockpit


113312 wrote:
The actions depend upon the model of 737 you are operating. Newer ones have autobrakes and autospoilers. Both will activate when the trust levers are retarded in a rejected takeoff. However, it is the pilots responsibility to follow up that the spoilers did deploy and that the aircraft is decelerating. Autobrakes in RTO mode should provide optimum braking all the way to a full stop. However, it is human instinct to apply manual brakes which will kick off the autobrake function. In the old days on 707s and 727s without these features, the drill was: thrust levers idle, apply maximum brakes, speed brake lever extend. This is done without delay. Yes, there is a directional control element in the case of loss of thrust in an engine. But not all rejected takeoffs are from an engine failure. Even when there is asymmetric trust, maintaining directional control should be an instinctive reaction of the pilot with the rudder and should not result in significant deviation on the runway.


The instinct to apply manual braking is one of the reasons your heels should be on the floor during the takeoff roll. That way you can steer but you can't apply the brakes without first raising your feet fully onto the pedals.
 
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Boair
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Re: Use of speedbrakes in Boeing 737 during RTO

Sun Jan 23, 2022 3:16 pm

I am not qualified on the 737 but did an MCC on the NG and from what I can remember we did in the sim:
As Starlionblue said, the captain will always have the hand on thrust levers until V1 and he will make the call and RTO, whether he is PF or PM. The procedure we used was (Captain):
1. Call "Reject", disengage autothrottle and apply maximum braking (manual or autobrake)
2. Close the thrust levers
3. Raise the speedbrakes lever
4. Maximum reverse thrust
All of this happen while the captain maintain the aircraft on the centerline.
Correct me if I'm wrong but we were told you first have to extend the speedbrakes and then only the reversers. Reason is that RTO distance are calculated only with speedbrakes so technically you only need them to stop, reversers are a "bonus" (and a useful one).
Braking was up to you but you have to check AUTO BRAKE DISARM light first. If the light was on or you preferred manual braking, you apply manual braking.
FO in the meantime cross-check the captain's actions (AUTO BRAKE DISARM light, speedbrakes, reversers...)
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Sun Jan 23, 2022 9:40 pm

Boair wrote:
I am not qualified on the 737 but did an MCC on the NG and from what I can remember we did in the sim:
As Starlionblue said, the captain will always have the hand on thrust levers until V1 and he will make the call and RTO, whether he is PF or PM. The procedure we used was (Captain):
1. Call "Reject", disengage autothrottle and apply maximum braking (manual or autobrake)
2. Close the thrust levers
3. Raise the speedbrakes lever
4. Maximum reverse thrust
All of this happen while the captain maintain the aircraft on the centerline.
Correct me if I'm wrong but we were told you first have to extend the speedbrakes and then only the reversers. Reason is that RTO distance are calculated only with speedbrakes so technically you only need them to stop, reversers are a "bonus" (and a useful one).


I need just a small clarification: can You confirm that "while the captain maintain the aircraft on the centerline" means "while the captain is taking actions to restore the original heading of the aircraft" and not "when the captain have restored the original heading of the aircraft and keeps it's course straight"?
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Sun Jan 23, 2022 9:56 pm

Starlionblue wrote:
IanfromRussia wrote:
Starlionblue wrote:
Ianfromrussia, you seem very concerned about reaction times. In general terms, I would say that in an airliner it is typically better to take a bit longer making a decision than to rush things. An extra second or two, even in the case of a rejected takeoff decision, won't make a material difference.

Also, airliners are certified for controllability in abnormal situations. If a pilot of average skill cannot control the worst-case thrust asymmetry, the airliner would not be certified.
"


Do You mean that if the aircraft suddenly begins to veer off the centerline of a wet 140 ft wide runway and full rudder deflection appears just a bit short of stopping it doing so than an extra second or two before beginning to retard the thrust levers won't make a material difference?

I understand well that the aircraft are designed to be controllable in abnormal situations by an average pilot (with certain caveats). I may seem to be concerned with reaction times but not in the sense of believing that they are inadequate. I only try to learn what course of action is proper to fully exploit the capabilities of the aircraft and of an average pilot in certain scenarios. To put it plainly, I try to learn how an RTO (especially a most challenging case) looks from the cockpit.


As 113312 says above, if the aircraft starts to veer off the centreline the PF will correct almost without conscious thought. There is no delay. For retarding thrust, there's already a one-second reaction time buffer. Additionally, the calculations have a safety factor. So yes, if you delay pulling the thrust levers to idle for a couple seconds, you should still be able to stop.


So may it be stated that an average pilot have under such scenario a generous margin for error? Or, in other words, does this scenario require him to be careful of not falling below average?
 
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Starlionblue
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Re: Use of speedbrakes in Boeing 737 during RTO

Sun Jan 23, 2022 11:34 pm

IanfromRussia wrote:
Boair wrote:
I am not qualified on the 737 but did an MCC on the NG and from what I can remember we did in the sim:
As Starlionblue said, the captain will always have the hand on thrust levers until V1 and he will make the call and RTO, whether he is PF or PM. The procedure we used was (Captain):
1. Call "Reject", disengage autothrottle and apply maximum braking (manual or autobrake)
2. Close the thrust levers
3. Raise the speedbrakes lever
4. Maximum reverse thrust
All of this happen while the captain maintain the aircraft on the centerline.
Correct me if I'm wrong but we were told you first have to extend the speedbrakes and then only the reversers. Reason is that RTO distance are calculated only with speedbrakes so technically you only need them to stop, reversers are a "bonus" (and a useful one).


I need just a small clarification: can You confirm that "while the captain maintain the aircraft on the centerline" means "while the captain is taking actions to restore the original heading of the aircraft" and not "when the captain have restored the original heading of the aircraft and keeps it's course straight"?


It is "while". The captain will be keeping the aircraft on heading the entire time, with perhaps a momentary deviation if there is a significant and sudden asymmetry. It's just instinctive correction with the rudder pedals. It happens at the same time as the other actions like thrust to idle and reverse (and spoilers unless they auto-deploy). You never interrupt maintaining the correct heading to do other things.


IanfromRussia wrote:
Starlionblue wrote:
IanfromRussia wrote:

Do You mean that if the aircraft suddenly begins to veer off the centerline of a wet 140 ft wide runway and full rudder deflection appears just a bit short of stopping it doing so than an extra second or two before beginning to retard the thrust levers won't make a material difference?

I understand well that the aircraft are designed to be controllable in abnormal situations by an average pilot (with certain caveats). I may seem to be concerned with reaction times but not in the sense of believing that they are inadequate. I only try to learn what course of action is proper to fully exploit the capabilities of the aircraft and of an average pilot in certain scenarios. To put it plainly, I try to learn how an RTO (especially a most challenging case) looks from the cockpit.


As 113312 says above, if the aircraft starts to veer off the centreline the PF will correct almost without conscious thought. There is no delay. For retarding thrust, there's already a one-second reaction time buffer. Additionally, the calculations have a safety factor. So yes, if you delay pulling the thrust levers to idle for a couple seconds, you should still be able to stop.


So may it be stated that an average pilot have under such scenario a generous margin for error? Or, in other words, does this scenario require him to be careful of not falling below average?


There is a margin for error like in all of aviation. With adequate training, a pilot who has passed the requisite checks to hold his/her position should be able to perform the tasks required.

I don't quite understand what you mean "careful of not falling below average"? We have to meet the required standard, both when on check, and when flying the line.
 
BoeingGuy
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 12:21 am

bigb wrote:
I can comment on the 737, but the 747 and I know 777. The speed brakes will auto deploy in the event of a RTO when the thrust levers reduced to idle and TR deployed to reverse Idle above 80 knots.


The 787 and 777-9 are the only Boeing models in which the speedbrakes will deploy as part of the Autobrake RTO function. You don’t even have to deploy the Thrust Reversers. As soon as you retard the trust levers to idle, when above 85 knots and RTO autobrakes armed, the speedbrakes will deploy.

All other Boeing models have an interlock such that when the thrust reverser handles are raised, the speedbrakes will also deploy. Several other posters have mentioned this.

The reason Boeing has recommended manually deploying speedbrakes during an RTO, even with the T/R interlock, is because the reliability numbers of that interlock function working didn’t meet the required reliability for the hazard level of the speedbrakes not deploying during an RTO. Last I heard, Boeing was re-evaluating that guidance, but not sure what became of it.
 
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Starlionblue
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 4:27 am

I guess the Airbus auto-speedbrake thing is pretty reliable because a few years ago the RTO callout changed and "Spoilers" was removed.

It is now, "Reverse Green. Decel." only.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 8:04 am

Starlionblue wrote:
There is a margin for error like in all of aviation. With adequate training, a pilot who has passed the requisite checks to hold his/her position should be able to perform the tasks required.

I don't quite understand what you mean "careful of not falling below average"? We have to meet the required standard, both when on check, and when flying the line.


I understand that in every systematic practice some margin for error is always envisioned, like, for example, a mechanical part always has tolerances for its dimensions. But some parts have to be designed with tight tolerances while others don't have to.
So I just meant: how tight are tolerances for performance in the case of need to reject under these unfavorable conditions.

Yes, all pilots are trained to cope with a certain scope of abnormal situations and have to demonstrate their proficiency in checks. But the investigations of aviation accidents reveal that performance of some pilots during infrequent abnormal situations (sometimes rather mild ones) fell short of the training standards. Although aviation is a complex enterprise and a person may be proficient in one part of the trade and deficient in the other, in some cases the investigation revealed that the performance of the crew significantly deviated from their performance in simulator in that instead of taking sober deliberate actions they acted impulsively and inconsistently with their training i. e. they turned out to have no gut enough to cope with a real abnormal situation where one cannot walk home after a failure and where one doesn't expect a certain kind of problem in advance. Others got too startled to act in time, some showed outright complacency etc. Some accident pilots we revealed by the investigation to have a history of systematic violation of procedures and attitudes incompatible with the position of airline pilot. More often than not those people had accumulated multiple thousands of flight hours. It seems like they would end up their careers with an honourable retirement were it not for a rare technical glitch that happened to them. So there appears to be a (hopefully small) minority of airline pilots who are barely skillful enough for normal operations without being really fit for their position.
So, my question is: does a safely performed RTO under realistic unfavorable conditions adds any further credibility to the qualification of a captain who is known to have some thousands of flight hours or is it such an easy task that no pilot who was able to make a thousand flights without a crash can possibly screw it up?
Would it be really stressful for the crew? Can improper execution, like e.g. really slamming the TCLs back instead of smoothly retarding them in coordination with the legwork, turn an RTO into a disaster (specifically on a wet runway)? How easy is it to screw it up for a trained pilot?
Is a slack or an unmanly pilot going to accomplish it safely?
 
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Starlionblue
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 8:42 am

Is it really stressful? I don't think so. A good captain will be mentally ready to reject on every single takeoff. Just like we should be mentally ready to go around on every single approach.

How easy is it to screw up? I can't give you a value. Apart from the need for prompt action, there isn't anything super complicated about the manoeuvre itself. On a contaminated runway especially, particular attention must be paid to any drift, but this is trained for.


It is very important to remember that the vast majority of rejected takeoffs result in nothing more than hot brakes. You can't extrapolate information only from those events that ended up poorly. I don't know how many rejected takeoffs are performed a day but I'm guessing you'll see a decent number. They seldom make the news.


the investigations of aviation accidents reveal that performance of some pilots during infrequent abnormal situations (sometimes rather mild ones) fell short of the training standards.

Can you give specific examples?
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 10:34 am

Starlionblue wrote:

the investigations of aviation accidents reveal that performance of some pilots during infrequent abnormal situations (sometimes rather mild ones) fell short of the training standards.

Can you give specific examples?


What comes first to my mind:
- USAF KC-135R, T/N 63-8877 (2013)
- Colgan Air Flight 3407 (2009)
- Recent 737MAX crashes
(Lion Air Flight 610 and Ethiopian Airlines Flight 302, yes, I know that Boeing screwed it up even more);
- and perhaps Air France Flight 447 (2009).
 
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Starlionblue
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 11:06 am

The 737MAX crashes were in large part due to an undocumented feature and failure mode that the pilots were unaware of. It is hard to have a sufficiently high training standard for something you do not know about.

Air France 447. Somewhat maybe. Fatigue definitely a factor. More importantly, at the time high altitude upsets like that were not really trained for like today. It is worth noting that there had been events of pitot icing previously, none of which resulted in an accident. Again, the events that ended well don't make the news.

Colgan 3407. IIRC fatigue was a factor. But again, what about all those approaches in poor conditions that did not end up in a crash.


USAF KC-135R, T/N 63-8877 (2013). Maybe. But yet again we must ask how many similar malfunctions did not lead to a crash.


Training standards are not magic. Sometimes pilots fall short. And sometimes the Swiss cheese lines up just right with a malfunction and other factors. In almost all cases, however, pilots do not fall short and there is no accident.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 2:25 pm

Starlionblue wrote:

Air France 447. Somewhat maybe. Fatigue definitely a factor. More importantly, at the time high altitude upsets like that were not really trained for like today. It is worth noting that there had been events of pitot icing previously, none of which resulted in an accident. Again, the events that ended well don't make the news.

Colgan 3407. IIRC fatigue was a factor. But again, what about all those approaches in poor conditions that did not end up in a crash.


USAF KC-135R, T/N 63-8877 (2013). Maybe. But yet again we must ask how many similar malfunctions did not lead to a crash.


That's the point! Not all trained pilots are equal. Some (hopefully most of them) worth their salt and some probably don't. And there are situations that are more or less testing for their proficiency and aptitude. Like approaches in marginal conditions, failure of handling augmentation devices (e. g. yaw dumper), pitot icing, abrupt engine failures in critical phases of flight etc. I used to believe, perhaps erroneously as it now seems, that certain unfavorable scenarios of RTO are among them (most RTOs actually are low speed RTOs for minor glitches done without any thrust assimetry and that's not what I'm speaking of). Now I begin to suspect that no realistic scenario of RTO may be compared in difficulty to those situations I've listed above.
 
VMCA787
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 2:40 pm

I really can't add much more than what Starlionblue has added but I think you are overanalyzing the entire situation. First of all, given the number of movements during "normal" times and the relatively few incidents of RTO at high speed, I would say you are looking for a problem when no problem exists.

I am retired now, but I can count on one hand and have fingers left over the amount of RTOs I have experienced in over 50 years of flying in both military and airline operations. I have been a trainer, evaluator and the entire process should be "automatic" for the PF. During the takeoff briefing, one thing I always referred to was the concept both Boeing and Airbus use in aiding pilots with the entire decision to reject or continue. Studies and statistics show the crew is much better off by getting the aircraft in the air versus a high-speed RTO. Personally, unless I am convinced the aircraft will not get airborne, I will continue the takeoff. Nothing has to be done "in a hurry". That is probably the biggest error I see in the sim during training and checks.

I started my airline career with a US 121 carrier that had red tails on all their aircraft. They were overly conservative when it came to RTO and used "wet" V speeds to lower the V1 speed to get the pilots "go" oriented. And it worked.
 
IanfromRussia
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 4:41 pm

VMCA787 wrote:
I really can't add much more than what Starlionblue has added but I think you are overanalyzing the entire situation. First of all, given the number of movements during "normal" times and the relatively few incidents of RTO at high speed, I would say you are looking for a problem when no problem exists.

I am retired now, but I can count on one hand and have fingers left over the amount of RTOs I have experienced in over 50 years of flying in both military and airline operations. I have been a trainer, evaluator and the entire process should be "automatic" for the PF. During the takeoff briefing, one thing I always referred to was the concept both Boeing and Airbus use in aiding pilots with the entire decision to reject or continue. Studies and statistics show the crew is much better off by getting the aircraft in the air versus a high-speed RTO. Personally, unless I am convinced the aircraft will not get airborne, I will continue the takeoff. Nothing has to be done "in a hurry". That is probably the biggest error I see in the sim during training and checks.

I started my airline career with a US 121 carrier that had red tails on all their aircraft. They were overly conservative when it came to RTO and used "wet" V speeds to lower the V1 speed to get the pilots "go" oriented. And it worked.

I think that the misunderstanding is that I somehow appear to believe that RTOs are a major safety issue in civil aviation. I never meant to. I happened at my leisure to start trying my quill in fiction and endeavored to design and properly describe an RTO event as a part of the plot. Despite my engineering background I had to throw into wastebasket my first iteration after having read manuals and QRHs as it proved to be totally unrealistic. Then in attempting to create something realistic I felt that I needed some details about proper execution of the manuals that are obvious to an actual pilot but obscure to a layman. But to my disappointment it seems to turn out that no realistic scenario is challenging enough to show proficiency of the crew. My latest and possibly last hope is a scenario when a FADEC unit fails just after 80 kts and the engine is set uncommandedly and gets jammed at some intermediate power setting regardless of the TCL position. But it doesn't look especially promising either.
 
Woodreau
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 6:04 pm

No that won't work either, the other FADEC assumes engine control upon failure of the active FADEC.

if the second FADEC also fails, then the engine just stops working, it's not going to be in a state where it's uncontrollably producing thrust.

The chances of both FADEC units failing in quick succession is unlikely.

The transition of control from one FADEC to another is automatic and while warnings and cautions are inhibited during the takeoff phase, the pilots will be unaware that it has taken place. Once the takeoff inhibition is removed above 1500ft, the pilots will get their first notification of the FADEC failure.


You should find a simulator and see if you can get to experience a rejected take off or perform one yourself... It's not likely in the US, but it seems there are enough aviation enthusiasts who are able to get simulator time in Europe.
 
bigb
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 7:59 pm

BoeingGuy wrote:
bigb wrote:
I can comment on the 737, but the 747 and I know 777. The speed brakes will auto deploy in the event of a RTO when the thrust levers reduced to idle and TR deployed to reverse Idle above 80 knots.


The 787 and 777-9 are the only Boeing models in which the speedbrakes will deploy as part of the Autobrake RTO function. You don’t even have to deploy the Thrust Reversers. As soon as you retard the trust levers to idle, when above 85 knots and RTO autobrakes armed, the speedbrakes will deploy.

All other Boeing models have an interlock such that when the thrust reverser handles are raised, the speedbrakes will also deploy. Several other posters have mentioned this.

The reason Boeing has recommended manually deploying speedbrakes during an RTO, even with the T/R interlock, is because the reliability numbers of that interlock function working didn’t meet the required reliability for the hazard level of the speedbrakes not deploying during an RTO. Last I heard, Boeing was re-evaluating that guidance, but not sure what became of it.


Thanks, brain fart. I got the RTO triggers mixed up with the speedbrake triggers upon landing. Lots of different triggers for Autobrakes, RTO, Speedbrakes. They all start to run together.
 
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AirKevin
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Re: Use of speedbrakes in Boeing 737 during RTO

Mon Jan 24, 2022 10:50 pm

Woodreau wrote:
You should find a simulator and see if you can get to experience a rejected take off or perform one yourself... It's not likely in the US, but it seems there are enough aviation enthusiasts who are able to get simulator time in Europe.

You can certainly get simulator time in the United States, you just have to know where to look. The Delta Flight Museum in Atlanta has a 737-200 simulator. There's a facility in Miami that has a few. Those are the two I can think of off the top of my head.
 
AABusDrvr
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Re: Use of speedbrakes in Boeing 737 during RTO

Tue Jan 25, 2022 8:24 am

Boair wrote:
I am not qualified on the 737 but did an MCC on the NG and from what I can remember we did in the sim:
As Starlionblue said, the captain will always have the hand on thrust levers until V1 and he will make the call and RTO, whether he is PF or PM. The procedure we used was (Captain):
1. Call "Reject", disengage autothrottle and apply maximum braking (manual or autobrake)
2. Close the thrust levers
3. Raise the speedbrakes lever
4. Maximum reverse thrust
All of this happen while the captain maintain the aircraft on the centerline.
Correct me if I'm wrong but we were told you first have to extend the speedbrakes and then only the reversers. Reason is that RTO distance are calculated only with speedbrakes so technically you only need them to stop, reversers are a "bonus" (and a useful one).
Braking was up to you but you have to check AUTO BRAKE DISARM light first. If the light was on or you preferred manual braking, you apply manual braking.
FO in the meantime cross-check the captain's actions (AUTO BRAKE DISARM light, speedbrakes, reversers...)



The biggest reason you want to get the speed brakes deployed, is to get the "weight" of the airplane off the wings, and on to the wheels. The brakes will do a much better job of stopping the airplane, than the reversers will.

Also, at my airline at least, it's policy on the 73 not to use manual braking during an RTO. If you disengage the auto brakes before the airplane is stopped, that will earn you at a minimum a debrief, and most likely you will be doing it over again before your sim session is over. The reasoning there is RTO brakes provide the maximum possible stopping effort, much better than maximum manual braking.
 
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77west
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Re: Use of speedbrakes in Boeing 737 during RTO

Tue Jan 25, 2022 9:03 am

AABusDrvr wrote:
Boair wrote:
I am not qualified on the 737 but did an MCC on the NG and from what I can remember we did in the sim:
As Starlionblue said, the captain will always have the hand on thrust levers until V1 and he will make the call and RTO, whether he is PF or PM. The procedure we used was (Captain):
1. Call "Reject", disengage autothrottle and apply maximum braking (manual or autobrake)
2. Close the thrust levers
3. Raise the speedbrakes lever
4. Maximum reverse thrust
All of this happen while the captain maintain the aircraft on the centerline.
Correct me if I'm wrong but we were told you first have to extend the speedbrakes and then only the reversers. Reason is that RTO distance are calculated only with speedbrakes so technically you only need them to stop, reversers are a "bonus" (and a useful one).
Braking was up to you but you have to check AUTO BRAKE DISARM light first. If the light was on or you preferred manual braking, you apply manual braking.
FO in the meantime cross-check the captain's actions (AUTO BRAKE DISARM light, speedbrakes, reversers...)



The biggest reason you want to get the speed brakes deployed, is to get the "weight" of the airplane off the wings, and on to the wheels. The brakes will do a much better job of stopping the airplane, than the reversers will.

Also, at my airline at least, it's policy on the 73 not to use manual braking during an RTO. If you disengage the auto brakes before the airplane is stopped, that will earn you at a minimum a debrief, and most likely you will be doing it over again before your sim session is over. The reasoning there is RTO brakes provide the maximum possible stopping effort, much better than maximum manual braking.


This exactly. The RTO setting I believe keeps the wheels on the knife edge of slip/lockup, which is also the maximum stopping effort available. A human could not do this without either under-braking or locking up the wheels. Much like the antiskid on a car but much more powerful.

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