Final Report: April 2018 737 high speed aborted TO
Approximately at V1 (cannot be confirmed in FDA) the TO Configuration Warning came up both visual and aural.
It’s an interesting one. Although a config warning >80kts is not specifically included in the list of RTO triggers, there is the catch-all of “...if the airplane is unsafe or unable to fly”. As there are quite a few things that can cause a config warning, some of them pretty serious, it’s not completely cut-and-dried. If flaps and/or LEDs decided to retract themselves (has happened), flying becomes much more difficult and may not even be possible in the remaining distance - you might have the choice of going off the end at low speed or high speed. A suspicion that the speed brakes may have been deployed likely didn’t help, either.
These kind of scenarios are worth thinking a little bit about ahead of time as what condition(s) would you regard as “unsafe or unable to fly”? It’s not something much trained/practiced as the result could well be an overrun/crash, which could lead to negative training outcome, even though the exercise was successful. For the avoidance of doubt, I firmly support the take-it-into-the-air-and-deal-with-it logic when close to or above V1, just that there is always an exception to a rule somewhere.
What appears at first reading to have contributed to the overrun once the RTO was initiated was manual braking. Autobrake, according to the graphs, would have stopped the aircraft on the paved surface...
These kind of scenarios are worth thinking a little bit about ahead of time as what condition(s) would you regard as “unsafe or unable to fly”? It’s not something much trained/practiced as the result could well be an overrun/crash, which could lead to negative training outcome, even though the exercise was successful. For the avoidance of doubt, I firmly support the take-it-into-the-air-and-deal-with-it logic when close to or above V1, just that there is always an exception to a rule somewhere.
What appears at first reading to have contributed to the overrun once the RTO was initiated was manual braking. Autobrake, according to the graphs, would have stopped the aircraft on the paved surface...
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Very true. However, this disclaimer is usually made to state that the report may not be used in tort litigation. That's my understanding. Ultimately someone or something or some combination of the two always receive some 'blame'. It's not necessarily a bad thing, unless it's the common practice certain airline manufacturers have of blaming pilots where there's a faulty design, mechanical defect, etc etc. (*cough* Airbus). But, yeah, there's a reason the full quote there is:
It is not the purpose to apportion blame or liability (Annex 13 to the Chicago Convention and Civil Aviation Regulations 2016).
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Maybe the mob I work for is an exception but startle events like a master caution approaching V1 is routinely trained in the simulator.
As is removing your hand from the thrust levers at V1.
Not being judgemental to point out that on a balanced field length T/O you ARE going off the runway if you reject after V1.
”Unsafe or unable to fly” is the get out of jail card , but it is the very last resort.
As is removing your hand from the thrust levers at V1.
Not being judgemental to point out that on a balanced field length T/O you ARE going off the runway if you reject after V1.
”Unsafe or unable to fly” is the get out of jail card , but it is the very last resort.
Yeah right...
Last edited by B2N2; 26th Jan 2021 at 22:57.
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White Knight
AIRBUS FCTM
Below 100 kt:
The decision to reject the takeoff may be taken at the Captain's discretion, depending on
the circumstances.
The Captain should seriously consider discontinuing the takeoff, if any ECAM
warning/caution is activated.
Above 100 kt, and below V1:
Rejecting the takeoff at these speeds is a more serious matter, particularly on slippery
runways. It could lead to a hazardous situation, if the speed is approaching V1. At these
speeds, the Captain should be "go-minded" and very few situations should lead to the
decision to reject the takeoff:
1. Fire warning, or severe damage
2. Sudden loss of engine thrust
3. Malfunctions or conditions that give unambiguous indications that the aircraft will not fly
safely
4. Any red ECAM warning
5. Any amber ECAM caution listed bellow:
‐ F/CTL SIDESTICK FAULT
‐ ENG FAIL
‐ ENG REVERSER FAULT
‐ ENG REVERSE UNLOCKED
‐ ENG 1(2) THR LEVER FAULT
Exceeding the EGT red line or nose gear vibration should not result in the decision to reject
takeoff above 100 kt.
In case of tire failure between V1 minus 20 kt and V1, unless debris from the tires has
caused serious engine anomalies, it is far better to get airborne, reduce the fuel load, and
land with a full runway length available.
The V1 call has precedence over any other call.
Above V1:
Takeoff must be continued, because it may not be possible to stop the aircraft on the
remaining runway.
Airbus FCTM
AIRBUS FCTM
Below 100 kt:
The decision to reject the takeoff may be taken at the Captain's discretion, depending on
the circumstances.
The Captain should seriously consider discontinuing the takeoff, if any ECAM
warning/caution is activated.
Above 100 kt, and below V1:
Rejecting the takeoff at these speeds is a more serious matter, particularly on slippery
runways. It could lead to a hazardous situation, if the speed is approaching V1. At these
speeds, the Captain should be "go-minded" and very few situations should lead to the
decision to reject the takeoff:
1. Fire warning, or severe damage
2. Sudden loss of engine thrust
3. Malfunctions or conditions that give unambiguous indications that the aircraft will not fly
safely
4. Any red ECAM warning
5. Any amber ECAM caution listed bellow:
‐ F/CTL SIDESTICK FAULT
‐ ENG FAIL
‐ ENG REVERSER FAULT
‐ ENG REVERSE UNLOCKED
‐ ENG 1(2) THR LEVER FAULT
Exceeding the EGT red line or nose gear vibration should not result in the decision to reject
takeoff above 100 kt.
In case of tire failure between V1 minus 20 kt and V1, unless debris from the tires has
caused serious engine anomalies, it is far better to get airborne, reduce the fuel load, and
land with a full runway length available.
The V1 call has precedence over any other call.
Above V1:
Takeoff must be continued, because it may not be possible to stop the aircraft on the
remaining runway.
Airbus FCTM
So the AAIB concluded that the decision to conduct a RTO above V1 was the correct course of action. Against the words of the manufacturer and SOP at almost every other carrier in the world.
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Vilas,
Why you've quoted the Airbus FCTM I've no idea, regardless of protocol as Captain the ultimate decision is with him.
There have been a number of incidents where take off has been rejected at or after V1 where carrying on would have led to a certain crash. It wasn't perfect but no injuries and damage limited to tyres being swapped out, I could live with that because like most of the folk on here I'm not striving for perfection, just trying to get it right.
Why you've quoted the Airbus FCTM I've no idea, regardless of protocol as Captain the ultimate decision is with him.
There have been a number of incidents where take off has been rejected at or after V1 where carrying on would have led to a certain crash. It wasn't perfect but no injuries and damage limited to tyres being swapped out, I could live with that because like most of the folk on here I'm not striving for perfection, just trying to get it right.
George Glass
Same here but do you practice an “unsafe or unable to fly” level defect being introduced at that point, such that you would crash if an attempt to fly was made? I suspect MCs, etc. are used more to reinforce the idea of continuing than to introduce doubt about whether you should? This is normal practice as on 99.99% of occasions it is the correct course of action but Boeing wouldn’t have included the above phrase in the QRH/FCTM if they didn’t think it might be needed at some point.
In the incident under discussion, it’s not clear precisely when the warning occurred but the RTO was initiated 3sec/10kts after V1. Given the startle effect, that would indicate that the warning was somewhere close to V1 but could have been either side of it. There is no information as to whether the PF had removed their hand or not at V1 - they might have done but put them back to initiate the stop.
It’s not textbook handling by any means but it’s not a textbook airfield or terrain, weather, density altitude, problem, etc. Compared to crossing the threshold at 200kts and trying to land half way down a wet runway with a tailwind, it seems they might have been a little unfortunate in the timing of the warning as the realisation, decision and initial actions were clustered around V1?
Same here but do you practice an “unsafe or unable to fly” level defect being introduced at that point, such that you would crash if an attempt to fly was made? I suspect MCs, etc. are used more to reinforce the idea of continuing than to introduce doubt about whether you should? This is normal practice as on 99.99% of occasions it is the correct course of action but Boeing wouldn’t have included the above phrase in the QRH/FCTM if they didn’t think it might be needed at some point.
In the incident under discussion, it’s not clear precisely when the warning occurred but the RTO was initiated 3sec/10kts after V1. Given the startle effect, that would indicate that the warning was somewhere close to V1 but could have been either side of it. There is no information as to whether the PF had removed their hand or not at V1 - they might have done but put them back to initiate the stop.
It’s not textbook handling by any means but it’s not a textbook airfield or terrain, weather, density altitude, problem, etc. Compared to crossing the threshold at 200kts and trying to land half way down a wet runway with a tailwind, it seems they might have been a little unfortunate in the timing of the warning as the realisation, decision and initial actions were clustered around V1?
Sometimes doing your best is not good enough. Sometimes you must do what is required.
- “Churchill"
'… a number of incidents where take off has been rejected at or after V1 where carrying on would have led to a certain crash.''
Certainty' is word which requires careful use in aviation, and begs examples, open to different viewpoints, moderated by context, and supported with facts.
With one possible exception I cannot recall an aircraft which would have been unable to fly - even if investigations suggest otherwise.
'… and possibly a serious aerodynamic issue such as a flap asymmetry.'
All things are 'possible', but few actually happen. The safety requirements for flap asymmetry would involve a similar level of integrity as a wing falling off.
Instructors, simulator scenarios must temper what is chosen for example; it is easier impart dramatic mind numbing situations, than focus on the simple 'mistakes'.
Mis-set flap, incorrect speed, weight, thrust, or no flap with MEL alert. Real events, not RTO scenarios, but more likely 'off-the-end', 'unable-to-fly' situations where training, knowledge, discipline might help.
'… a number of incidents where take off has been rejected at or after V1 where carrying on would have led to a certain crash.''
Certainty' is word which requires careful use in aviation, and begs examples, open to different viewpoints, moderated by context, and supported with facts.
With one possible exception I cannot recall an aircraft which would have been unable to fly - even if investigations suggest otherwise.
'… and possibly a serious aerodynamic issue such as a flap asymmetry.'
All things are 'possible', but few actually happen. The safety requirements for flap asymmetry would involve a similar level of integrity as a wing falling off.
Instructors, simulator scenarios must temper what is chosen for example; it is easier impart dramatic mind numbing situations, than focus on the simple 'mistakes'.
Mis-set flap, incorrect speed, weight, thrust, or no flap with MEL alert. Real events, not RTO scenarios, but more likely 'off-the-end', 'unable-to-fly' situations where training, knowledge, discipline might help.
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Lots of this stuff is for back in the classroom & CRM etc. What should come out of it is that V1 is the line. Stop before, go after. End of. Sim should then re-enforce so that, really we get into an action for all cases. No discussion. Longest runway in the world, no obstacles in front or behind, V1 occurring with miles of concrete in front (?)- STOP for heavens sake because that is what we do all the time. Next day, you could be on a very limiting & challenging set of conditions. Up to 80k, stop for anything, even uncontrollable flatulence , 80-V1, only for well specified and briefed circumstance, after V1....................go...................pleeeze !
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You pass V1, start to rotate and nothing happens. What do you then? Happened twice in my company.
There will always be a situation outside the box.
On the other hand, a very long runway doesn't mean you have the brake energy to stop at very high weight/speeds.
There will always be a situation outside the box.
On the other hand, a very long runway doesn't mean you have the brake energy to stop at very high weight/speeds.
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It is not the purpose to apportion blame or liability (Annex 13 to the Chicago Convention and Civil Aviation Regulations 2016).
You pass V1, start to rotate and nothing happens. What do you then?
Good question, but as a professional there should be an answer.
Jammed control drill, failure to rotate drill. Some aircraft - pull harder, announce the condition, both pilots pull, split the controls if the automatic systems has not done so (improbable second failure).
When was this last practiced in the sim; were the forces involved surprisingly high - something which you would not normally consider.
Alternatively, before such situations are encountered, consider:- cg verified, trim setting, when and how the before-takeoff-control check is done; a snowy day, what deicing procedures were used, hold over time.
Its easy to quote the negative, more difficult to think about the positive.
Anyway what happened on those two occasions; accidents avoided because of a long runway. What was the issue which contributed to the situation.
What was learnt, what might we learn.
https://fs.blog/2021/01/practice-failure/
If we don’t practice failing, we can only safely fly on sunny days.
Good question, but as a professional there should be an answer.
Jammed control drill, failure to rotate drill. Some aircraft - pull harder, announce the condition, both pilots pull, split the controls if the automatic systems has not done so (improbable second failure).
When was this last practiced in the sim; were the forces involved surprisingly high - something which you would not normally consider.
Alternatively, before such situations are encountered, consider:- cg verified, trim setting, when and how the before-takeoff-control check is done; a snowy day, what deicing procedures were used, hold over time.
Its easy to quote the negative, more difficult to think about the positive.
Anyway what happened on those two occasions; accidents avoided because of a long runway. What was the issue which contributed to the situation.
What was learnt, what might we learn.
https://fs.blog/2021/01/practice-failure/
If we don’t practice failing, we can only safely fly on sunny days.
Landflap
Rare occurance but still,
https://skybrary.aero/index.php/MD83...i_MI_USA,_2017
The following crew obviously should have rejected the take off even after V1, alas no config warning due to either a malfunction or a pulled (?) breaker.
https://en.wikipedia.org/wiki/Spanair_Flight_5022
The original incident? Good decision on the reject then buggered up the process.
Nobody got hurt, tires got replaced, plane got washed, back in business.
Rare occurance but still,
https://skybrary.aero/index.php/MD83...i_MI_USA,_2017
The following crew obviously should have rejected the take off even after V1, alas no config warning due to either a malfunction or a pulled (?) breaker.
https://en.wikipedia.org/wiki/Spanair_Flight_5022
The original incident? Good decision on the reject then buggered up the process.
Nobody got hurt, tires got replaced, plane got washed, back in business.
Last edited by B2N2; 27th Jan 2021 at 15:22.
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safetypee
This was some 20+ years ago, and happened to two MD-80s. The MD-80 elevator is not powered, but controlled by tabs. Residue of deice fluid (type IV, new at the time if I remember correctly) build up inside the elevator system and jammed it. The flight control check only moves the tabs, so nothing unusual during the flight control check. Both aborted above VR and managed to stop. Luckily, and the correct decision by both captains.
A GO decision would most likely have killed a lot of people. Yes, a long runway did help.
This was some 20+ years ago, and happened to two MD-80s. The MD-80 elevator is not powered, but controlled by tabs. Residue of deice fluid (type IV, new at the time if I remember correctly) build up inside the elevator system and jammed it. The flight control check only moves the tabs, so nothing unusual during the flight control check. Both aborted above VR and managed to stop. Luckily, and the correct decision by both captains.
A GO decision would most likely have killed a lot of people. Yes, a long runway did help.
After V1 you only abort if running of the end at low speed during abort is better than failing to fly at high speed. As we can never put every conceivable failure in the checklist there will alway be the discussion afterwards if it was the right decision. If Sully had hit the geese between V1 and Vr, and overrun into the water aborting it would be the right decision, because you can’t fly with both engines failed. If you think the speed brakes are stuck in the up position it might be the right decision, I wasn’t there.....