Final Report: April 2018 737 high speed aborted TO [Archive]

Uplinker

26th Jan 2021, 10:22

Yes, and on the other hand, had there been an actual config problem and PIC had continued the take-off towards mountains in poor weather and then crashed because the speed brakes were deployed, would we be condemning those actions?

This was clearly not PIC's finest hour, and it would seem that recurrent SIM training in this airline had not focused on practising the basics, such as RTOs. In addition, it would appear that B737 speed-brake lever position switches can be less than precise, so crews are probably used to having to jiggle the damn thing on occasion, (this is certainly my experience of old B737 classics, but this was not an old classic).

When the alleged config warning occurred at V1, PIC would have been go minded, and probably thought a quick jiggle of the speed-brake would stop the alarm. Where it all unraveled though was that the alarm was not stopped and PIC then wasted several seconds thinking about the config alarm rather than continuing or stopping. By V1, the first actions of an RTO must have been started, otherwise the take-off must be continued.

According to the report the crews' knowledge of RTO was not solid, and during briefings I have sometimes started to review RTO reasons and actions, only to be interrupted by PIC, saying "yes, yes, that's all SOPs".
Finally, I do not accept the so-called "startle effect", especially on take-off, when one should be prepared for anything. We are supposed to be trained and prepared for things to go wrong. Good PICs I have observed, go through a silent touch drill of the stopping actions before starting the take-off roll.

George Glass

26th Jan 2021, 11:45

Extract from QRH;

“Rejected Takeoff
The Captain has the sole responsibility for the decision to reject the takeoff. The decision must be made in time to start the rejected takeoff manoeuvre by V1. If the decision is to reject the takeoff, the Captain must clearly announce “STOP,” immediately start the rejected takeoff manoeuvre and assume control of the airplane. If the First Officer is making the takeoff, the First Officer must maintain control of the airplane until the Captain makes a positive input to the controls.
Prior to 80kt, the takeoff should be rejected for any of the following: • activation of the master caution system
• system failure(s)
• unusual noise or vibration
• tyre failure
• abnormally slow acceleration
• takeoff configuration warning
• fire or fire warning
• engine failure
• predictive windshear warning
• if a side window opens
• if the airplane is unsafe or unable to fly.
Above 80 knots and prior to V1, the takeoff should be rejected for any of the following:
• fire or fire warning
• engine failure
• predictive windshear warning
• if the airplane is unsafe or unable to fly.
During the takeoff, the crew member observing the non-normal situation will immediately call it out as clearly as possible.”

The assumption is that a genuine configuration problem will be obvious on hitting TOGA at the start of takeoff and below 80 kts.

Timmy Tomkins

26th Jan 2021, 12:34

I'm not a 737 jock, so maybe a silly question but no mention of reverse thrust; would that usually be deployed?

ManaAdaSystem

26th Jan 2021, 13:22

Yes, but they are not included in the take off calculation (on a dry runway) so you will normally stop on a shorter distance than what the data says.
IF you do the reject in the correct way.

WingNut60

26th Jan 2021, 13:30

Malindo. Big brother or kissing cousin to Lion Air.
Take a look at some of the other threads if you want a few clues.

MikeSnow

26th Jan 2021, 13:54

Actually, it is mentioned in appendix 5 containing the Boeing Investigation Report, starting at the 4th page of that appendix. They used reverse detent 2 instead of maximum reverse thrust. There are also mentions on the following pages, for example from page 6 of that appendix:

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/761x111/image_b52aecb10882da2d10d71195c54191b9cf912eb8.png

safetypee

26th Jan 2021, 14:29

George, #12, agree, except we cannot know that the aircraft is unsafe or unable to fly.
Previous QRH items are fact; 'unsafe', 'unable' are … unknowable.
Yes, it's the Captains call, judgement, but what is judgement … .
Hindsight is the gap between an event and subsequent analysis.
Surprise is when fear overcomes fact.
Fear is also when we are unable define every situation before the event. Its these which we should 'fear' before the event, think about how we react to uncertainty in situations.

After the event 'fact' is only opinion; a forum post, a realisation that we had not thought about these situations beforehand. Alternatively with prior thought, not having considered every aspect, so there is still opportunity to learn.
Reduced safety margin when rejecting on a wet, downhill, rubber contaminated runway.

Uplinker,#11.
Our finest hour always precedes the outcome, but no-one knows that.
Config Warning is a difficult case, but the settings and alerting were correct at the start of the roll.
Certification requirements are (statistically) sufficient to eliminate false activation thereafter. We trust requirements in other instances, so why think otherwise in these situations; 'otherwise' involves surprise, lack of knowledge, biased training.

For those who change control for an RTO, consider the time taken; a further reduction in the available stopping distance.

This is a good safety investigation; but where is the strong recommendation that the manufacturer should improve the detent (> recc 4.5, 4.6). How many events are required, how many accidents …

ATC Watcher

26th Jan 2021, 15:09

I have worked in KTM a few years ago and there is enough aluminum scattered in the hills around the airport to make you you have an humble view of things.
Startle effect plus knowing the geography around KTM made them take that decision . We were not in their shoes on that flight , . What I see is embarrassment , but nobody hurt and an aircraft undamaged .Could have been worse , yes. But certainly much worse if they had anything less than 500ft/min after taking off for whatever reason. Their call.

B2N2

26th Jan 2021, 15:55

Et tu Brute?

Prime example of what often irritates me about Pprune, pedantic attitudes and that overall sense of superiority.
We all know that even after 14,000 hrs a career can be over in seconds.
There is a certain amount of luck required in this profession, we’ve all had our moments where skill had no part in the outcome.

what next

26th Jan 2021, 16:43

We all know that even after 14,000 hrs a career can be over in seconds.

And 200 human beings can be killed within the same number of seconds. In my book this pilot did the right thing. He decided to abort at V1 (for a good reason given where they were) and if he had applied full brakes and full reverser right form the beginning nobody would ever have heard about this incident. That an aircraft briefly continues to accelerate between the decision to abort and the beginning of the actual actions is figured into the calculations.
All this "I will abort for this and that below 80kt and for that and something else between 80 and V1" briefing bla-bla is nice in a classroom and maybe in a simulator (where already less than one half of pilots - me included - will get it right every time) but in real life it will be done wrong in the majority of cases. Because we are not machines. This is why the give us machines to facilitate our decisions, like this configuation warning system, but when those machines get it wrong we are even more alone than before.

flash8

26th Jan 2021, 17:26

Approximately at V1 (cannot be confirmed in FDA) the TO Configuration Warning came up both visual and aural.Oh, well we'll never know when will we since modesty prohibits me expounding my thoughts on the CVR "issues".

FullWings

26th Jan 2021, 18:29

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...

chriscrepon88

26th Jan 2021, 19:14

Page one: the purpose of the report is not to apportion blame!!

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).

George Glass

26th Jan 2021, 21:38

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.

B2N2

26th Jan 2021, 22:43

Oh, well we'll never know when will we since modesty prohibits me expounding my thoughts on the CVR "issues".

Mmmm... and you would take an airplane up in some of the worlds highest terrain, at night, with rain showers and thunderstorms....and possibly a serious aerodynamic issue such as a flap asymmetry?
Yeah right...

vilas

27th Jan 2021, 05:55

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

Icarus2001

27th Jan 2021, 06:18

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.

:rolleyes:

Momoe

27th Jan 2021, 06:24

B2N2,

Well said, stones and cast springs to mind.

50m overrun or potential for unscheduled arrival, not too much thinking required

DaveReidUK

27th Jan 2021, 06:32

Original thread on the incident from 2018:

PPRuNe: Why is Kathmandu Closed? (https://www.pprune.org/rumours-news/607986-why-kathmandu-closed.html)

Momoe

27th Jan 2021, 06:34

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.

FullWings

27th Jan 2021, 08:09

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?

safetypee

27th Jan 2021, 08:19

- “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.

Landflap

27th Jan 2021, 08:44

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 !

ManaAdaSystem

27th Jan 2021, 10:17

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.

vilas

27th Jan 2021, 11:27

It is not the purpose to apportion blame or liability (Annex 13 to the Chicago Convention and Civil Aviation Regulations 2016).
Does it mean that the purpose of inquiry is to tell a bed time story? If an inquiry reveals that there was a deficiency of skill or procedural knowledge or maintenance so all that they can say is this wasn't done and that wasn't executed but no blame. The involved pilot will be given corrective training not because he did or didn't do something but just for fun? This fits the definition being politically correct which is defined as " trying to pick up piece of **** by its cleaner end".

ManaAdaSystem

27th Jan 2021, 12:42

You don't have a clue what you are talking about, Vilas.
First you mix Airbus procedures into an Boeing incident, and now this?

safetypee

27th Jan 2021, 13:11

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.

B2N2

27th Jan 2021, 15:11

Landflap

Rare occurance but still,
https://skybrary.aero/index.php/MD83,_Ypsilanti_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.

ManaAdaSystem

27th Jan 2021, 15:34

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.

hans brinker

27th Jan 2021, 16:12

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.....

vilas

27th Jan 2021, 16:18

ManaAdaSystem

I didn't mix AIRBUS but somebody wrongly quoted Airbus FCTM I just posted the correct version. Airbus also doesn't recommend reject after V1.

vilas

27th Jan 2021, 16:27

In the present case reject wasn't necessary but having decided to do it it should have been executed properly without wasting precious moments on any trouble shooting. In general if you cannot rotate even with proper procedure then reject is the only answer whatever the result.

Stuka Child

27th Jan 2021, 17:30

I was going to shut up, but I just can't. This is addressed to no one in particular, but to some of the arguments which have been presented here.

Every procedure, whether designed by the manufacturer or your company, is based on the assumption that a conscious mind operates your brain, and that said mind is capable of understanding and reacting to situations correctly, and making optimal if not the best decisions to give everyone on board the best chances of making it in one piece. If that weren't the case, there would be no pilots.

This whole "go-minded" stuff was not caused by horrible takeoff overrun accidents that killed everyone on board. Yes, people have tragically died in overruns (mostly on landing) and it is not something to take lightly. However, you have 1000 times more chances of dying in a LOC accident while in the air. The actual origins of these procedures are the following: X, Y, Z aviation safety people examined a series of aborted takeoff above V1 incidents (many not resulting in overruns mind you!) and figured out that most of these were perfectly flyable aircraft, and that the takeoff was aborted for some insufficient reason that in the heat of the moment seemed critical to the crew. Conclusion: there is statistically very rarely a valid reason to reject the takeoff after V1, so it makes sense numbers-wise to "force" pilots to press ahead, because much more people risk to lose their lives if we continue to allow these frivolous rejected takeoffs than the 200 lives we're going to save when once in a blue moon there is actually a valid reason to attempt to stop. Or, more cynically, it could be about tyre costs. Realistically, it's probably a bit of both.

Let's take an example where the runway is too short to stop once you've passed V1 and the overrun is guaranteed - which again is not always the case. Now think about it. What offers your passengers the best chance of survival? Driving into the forest at the end of the runway while slowing down? Or nosebombing the same forest from the air because you took off with your wing on fire like a dumbass? And it doesn't even have to be something as dramatic as a fire chewing off bits of airfoil. Anything that would cause an aircraft to refuse to fly is a great reason to stop, no matter the speed. Same if you suspect possible imminent structural failure (wing on fire example). For the life of me, I can't figure out why you would try to power your way through that.

Obstacles at the end of the runway and to the sides are a concern, of course, but you should already be aware of these things before you even report for duty. It is your job to know the aerodrome and have plans in case something goes wrong. Where are the obstacles in case of an overrun? Where can I go? If I have a dual engine failure, where can I go? If I'm already in the air, where can I put her down to give us the best chances? If you're thinking about these things during a takeoff run, you are late. This is no time to discover the layout of the airport. The homework should have been ready from before.

Making the correct decision within seconds is what saves lives or elevates them from this earthly plane in a violent manner. And despite what you might think, there is no procedures and no checklist for decision-making. That burden lies squarely on your shoulders. Try to get used to it.

what next

27th Jan 2021, 18:18

And despite what you might think, there is no procedures and no checklist for decision-making.

Excellent post, Stuka Child. This is the very reason why my alarm clock is set at 5:00 tomorrow morning because no one invented a device yet that could do that for me.

B2N2

28th Jan 2021, 04:36

We are but mere mortals some just more then others.

Captain Sullenberger and Captain Haynes come to mind.

We will all be judged by our decisions.

pineteam

28th Jan 2021, 04:58

The number of people who think it’s ok to reject take off above v1... What am I reading here?! Unless you lost a wing or something after V1 you go. Period.
Some guys survived miraculously car accidents without wearing a seat belt. Does that mean it’s the right thing to do? Certainly not cause it’s undeniable that wearing the seat belt is safer overall.
You pass V1, start to rotate and nothing happens. What do you then?.
We did that in the sim. Toga and rotate using the trim wheel

Edit: Nice Post Stuka Child!:D

George Glass

28th Jan 2021, 05:42

Some posters need to have a bit of a chat with their Check Captain about this issue at their next License Renewal sim. session.
Of course if ,in fact , they ever do one............

vilas

28th Jan 2021, 09:05

We are discussing a takeoff that was rejected for a wrong reason and not even correctly executed. There are hardly any accidents that required split second decision. In takeoff incidents wrong decision is the major cause. So let's not go overboard. Most accidents are caused by incorrect handling of straightforward procedures without any time constraint. After V1 only at Vr one will know whether aircraft will get off with only option of trying other side or stabilizer. If it doesn't then you reject and accept the result. But for this one in million hours possibility you cannot throw the standard procedure of being go minded out of the window.

Landflap

28th Jan 2021, 09:25

Pinetree & George, thank heavens. Thought I was on my own there ! Trust some of these posters are not pilots. I doubt that any professional, trained and practiced pilot would even contemplate stopping after V1.As I said before, keep the discussion in the classroom please. Out in the tough world, it is a no brainer. Boeing seem to agree. Airbus seem to agree. I got through 40 years of sim tests where if I continued after V1 but pleaded that I was "thinking outside of the box" I would have been granted a bit of re-education. Persisting in the dangerous delusion would have resulted in job termination. Quite rightfully so.

excrab

28th Jan 2021, 10:46

vilas

I would agree with all of that, except for the first part of the first sentence. Boeing are quite clear in the QRH, that:

Above 80 knots and before V1, reject the takeoff for any of the following:

any fire or fire warning

engine failure - confirmed by two parameters

blocked runway

take-off configuration warning

control malfunction

predictive windshear warning

if the airplane is unsafe or unable to fly.

That’s a cut and paste from the 737-800 QRH at the airline I currently fly from. The decision to stop was for a correct reason, if it was taken before V1, but the problem was in the execution, and that shouldn’t have been an issue because there are four simple steps in the initial RTO which any B737 captain should have engraved in their muscle memory, should review in the before take-off emergency brief, and be mentally rehearsing throughout the take-off role.

However, looking at the report, it would seem that despite what was written in the tech log the decision to reject was almost certainly taken above V1, and the process was slowed down further by attempting to fault find. Those were both errors which shouldn’t have happened, but in defence of the crew involved I wonder how much is due to the way simulator training is conducted. I’ve been flying the 737 for fifteen years, so nowhere near as long as some of the posters here. I’ve flown it for five airlines, so I’ve done about 26 recurrent checks and five OCC’s, three of which were excellent and covered virtually the whole type rating course, one of which included the type rating so was even better (that was the first one, obviously), and one of which was two sim sessions then a proficiency check, so wasn’t quite as good. But in every OCC except the initial type rating, and in every training or checking event, at five different airlines, every RTO has been for a fire or engine failure, and every RTO has been conducted with either 125 or 75 metres visibility, and every RTO has been initiated by a failure or fire two or three knots below V1 and every EFATO has been initiated 2 or 3 knots above V1 because the instructor or examiner has set that on the touch screen on their IOS because they either want you to stop or they want you to go, and don’t want some grey area right in the middle, exactly at V1 where in a non EFIS aircraft the width of the ASI needle can lead to discussion.

Not once, in any of those events, has the RTO been performed when taking off from a wet runway, in the dark, knowing that if we get airborne then at four hundred feet the LNAV is going to command an immediate right turn and we are then going to climb on a 4 DME arc around the Kathmandu VOR with the flaps out until we get to about three thousand feet above the airfield, which is going to take forever if we lose an engine, and we are going to climb to about twelve thousand feet to get across the foothills of the Himalayas to our take off alternate which is a dreadful sh*thole in India, and knowing that if we had a major control malfunction or a fire that wouldn’t go out then if we can’t get to that sh*thole our only option is, if we’re lucky and have the approval is to fly fourteen miles from Kathmandu and then return flying a curving RNP/AR approach through a narrow valley, or even worse, without the approval, fly a steep VOR approach where once you get to 4 DME and you’re visual, in the dark, in your burning or barely controllable aeroplane you are going to increase the rate of descent to get down onto the three degree PAPI slope for the visual landing, and if in the stress of all that, which you have never practised even in your Cat C training you get it wrong and have to go around then you are going around towards high ground where the MSA reaches 28,000 feet within 25 miles of the airfield.

Having been to Kathmandu many times, despite knowing that we stop below V1 and at or above V1 we go, I’m not sure, what I would have done, without the value of hindsight and a thread on prune to learn from, If I’d been in the left hand seat of that aircraft and had got a configuration warning at or slightly above V1, except I hope I wouldn’t have tried to find out if it was real, in the same way as we don’t try to find out if a fire warning is real, or a wind shear warning is real, we just assume it is and react. I’m probably going to get flamed for this by the pundits, but after thirty five years of flying for a living I’ve learned that it’s easy to sit in the back of a simulator or in an armchair and pontificate, but we weren’t there, and we shouldn’t vilify someone for a mistake which at some point in our careers, before we knew everything from reading prune, we could have made ourselves.

George Glass

28th Jan 2021, 11:02

Excrab , great post. ( Not being sarcastic! )
I have been to Kathmandu ( and Lukla ! )
I feel your pain.
But its your job.
That’s what you’re paid for.
When you do your flight planning , pre-flight briefing etc. and line up on the runway and press TOGA you should have a pretty comprehensive mental image of what you are going to do.
And be confident about it.
If you don’t you are in the wrong game.

sheppey

28th Jan 2021, 11:22

The Malaysian AAIB report agreed with the captain’s declaration to reject the takeoff was well taken since the captain said it was unsafe to continue considering the airport surrounding terrain and bad weather.

That said, some would argue the sound of the configuration warning at V1 was so inconsequential that a continued takeoff was a safer option than a high speed abort beyond V1 on a wet runway.

The Boeing report at Appendix 5 of the AAIB investigation made the following observations of the conduct of the abort. The aircraft had already passed the V1 of 141 knots when the captain initiated the abort. The QAR indicated the abort commenced ten knots after V1 – namely 151 knots which put the aircraft further down the runway which was already wet. The maximum speed reached was 154 knots before reducing. That is 13 knots beyond V1

The captain immediately overrode the RTO feature by using manual braking as the auto brakes actuated. The RTO feature applied instant 3000 PSI but this was reduced to 800 PSI the instant the captain applied manual braking. It gradually increased to 3000 PSI over the next 20 seconds. . Full reverse was not used.

Boeing stated: “During RTO, reverse thrust, wheel brakes and autobrake were used; however not to their maximum capability. Reverse detent was used instead of maximum reverse which would have been expected on a wet runway and commanded brake pressure was reduced from the autobrake applied brake pressure of 3000 PSI to 800 PSI and gradually increased back to maximum brake pressure over 20 seconds.”

To an informed observer it would appear the decision by the captain to abort beyond V1 was more a panic move rather than a fully considered decision of all the circumstances. If, as the captain stated, a takeoff configuration warning occurred as the aircraft passed V1, there is little doubt that there would have been a WTF moment startle factor and a momentary delay before he elected to continue the takeoff or reject.

It is doubtful if the captain at the time of the takeoff configuration warning, would have found the time to consider terrain and weather before making an informed decision. More likely he made a snap decision to abort. But why stop?

The fact he dithered with the speed brake handle after V1 would indicate he was caught by surprise while still accelerating. Maybe he hoped it would stop the configuration warning which was distracting. When the noise didn't stop he then instinctively initiated an abort because he didn't know what else to do.

Regardless of his handling errors during the abort which would suggest a degree of technical incompetency, it would appear that to the casual observer there could be only one reason for his action to abort beyond V1.

The captain’s considered on the spot opinion that the aircraft may not fly in terms of possible handling difficulties and unknown gradient of climb.

Or: A startle or WTF factor so strong that standard operating procedure as espoused by the aircraft manufacturer in the flight manual was overridden by the captain's primeval desire to stay on the ground regardless of stopping performance considerations. In other words a panic driven abort which fortunately caused no casualties. What do readers think?

IcePack

28th Jan 2021, 11:34

Reading this thread, I still get the impression, that a lot of pilots really do not understand the definition of V1 and how it relates to an abandon take off. I am sure someone on here can quote verbatim the definition. But for a start brakes should (already) be fully applied AT the V1 speed in the event of an abandon.

excrab

28th Jan 2021, 13:26

My understanding from the FAA rules is that V1 is either the maximum speed at which the RTO manoeuvre can be initiated, or the minimum speed at which a take off can safely be continued in the event of an engine failure. As we are talking about the stop
case here this means that at V1 we should be (in the 737) 1. Disconnecting the auto-throttle 2. Retarding the thrust levers 3. Deploying the speed brakes and 4. Deploy Max reverse thrust. As we carry out the second action the auto brakes kick in. So max braking will not be already applied at V1.

Uplinker

28th Jan 2021, 14:37

Yes, V1 is not the moment to start applying an RTO. When V1 is called by PM, it is already too late to begin a safe RTO - hence, many SOPs have the PIC removing their hands from the thrust levers as soon as V1 is called.

The actions of an RTO must already have been started by the time V1 is called - otherwise one must continue. What those actions are will vary between aircraft types.

Only in extremis should a stop be attempted after V1 - a catastrophic loss of control or airframe damage or separation etc.

PS, great post #50 exrab :ok:

safetypee

28th Jan 2021, 16:17

The origins of 'go minded' are from work on the FAA Takeoff Training Safety Aid circa 1992-94 AC120-62. At a similar time the definition of V1 was harmonised world wide; the FAA had to 'add' time for recognition used elsewhere, and redefine with 'first action'.

Some US operators had difficulty with this, resorting to 'procedural' adjustment - calling V1 slowly, or starting 5 kts before the decision speed.
Within this, the hypothetical cases appeared without due consideration of requirement or risk; also the Unions promoted 'Except', more for legal cover than safety or practicality. The result was a legacy of indecision and inaccuracy imposed on the world via FAA and Boeing / Douglas.
In later years Airbus have provided balancing views in a range of safety publications (no 'except' in their drill?)

An ideal procedure is a simple If-Then.
There are a few time-critical events requiring 'automatic' pre-conscious action with little need for situation assessment: 'Pull Up', 'Wind-shear', 'Descend'.
Conversely RTO is one, if not the only time-critical situation which requires situation assessment before acting.
The situations for 'automatic' action are defined by technical systems (EGPWS, TCAS).
RTO situations are defined by 'people', individual perception and assessment, judgement of 'failure', in a time limited period, with inherent bias of human thought.

We construct RTO situations in our head at the particular moment; our interpretation of reality.
How we 'create' these situations is the dominant factor in modern RTOs. Yet increasingly our minds are cluttered with inappropriate knowledge, ill-informed hypothesis and wild supposition from others. The unbalanced fears from extreme situations or outcome, or risk, will resurface from memories biasing our thoughts in those rare and surprising situations where the clarity of If-Then is required.

Dispel hypothesis with fact, validate assumptions, check regulations, and rationally evaluate risk. These with a 'go mindset' will help judge and choose an appropriate action.

No choice is perfect, but it should at least be well considered based on prior understanding and knowledge; then doing what is perceived to be correct, at the time, for 'your' situation, no one can rationally judge otherwise - because they were not there.

Stuka Child

28th Jan 2021, 16:29

pineteam

Thanks for the love :O

No one is saying it's ok to reject after/above V1, but it is an indisputable fact that in some rare cases this is exactly what one must do. I can name you off the top of my head accidents with heavy loss of life, or death of everyone onboard, where the correct action was to stop and take the overrun if needed, but the go-minded captain went...and came right back down in a big fireball.

Miraculous escapes from car accidents are not exactly the best comparison. Aborted takeoffs above V1 are a relatively common occurrence despite what is being suggested on these fora, and the VAST MAJORITY of them end with no major damage to the aircraft, let alone hull losses or fatalities.

If anyone would like to see some numbers to compare fatalities from RTOs above V1 vs loss of control immediately after takeoff, I would be more than happy to pull them up and compile them for your viewing pleasure.

PPRuNe is a funny place. Operate outside of procedures (or on the thin grey line) and keep everyone alive, you are pilloried. Do something really stupid and kill everyone, you become a martyr - "oh don't blame the pilots" and all that hoo-hah.

GlobalNav

28th Jan 2021, 17:27

We are but mere mortals some just more then others.

Captain Sullenberger and Captain Haynes come to mind.

We will all be judged by our decisions.

In the cases of these examples, the decisions were made long before, and habitually, before the famous incidents. Decisions which demonstrated their professionalism and preparing them as well as could be done for those brief and perhaps singular events that defined their long careers.

tdracer

29th Jan 2021, 00:15

George Glass

29th Jan 2021, 01:40

Stuka

You’re making it up.
Spot the Flight Sim. driver.
td is correct.
Put up the numbers or shut up.
Oh , but thats right , they don’t exist.

Icarus2001

29th Jan 2021, 02:44

If anyone would like to see some numbers to compare fatalities from RTOs above V1 vs loss of control immediately after takeoff, I would be more than happy to pull them up and compile them for your viewing pleasure. I would love to see the numbers, with their source data.

Chris2303

29th Jan 2021, 05:15

Incident: EAT Leipzig A306 at Brussels on Nov 26th 2020, rejected takeoff above V1 due to difficulties becoming airborne (http://avherald.com/h?article=4dfbfe95&opt=0)

Incident: EAT Leipzig A306 at Brussels on Nov 26th 2020, rejected takeoff above V1 due to difficulties becoming airborne

jmmoric

29th Jan 2021, 08:43

https://havarikommissionen.dk/luftfartsarkiv/2019/2019-234/

Think we can find a number of incidents where the decision to abort late in a departure was the correct choice.

Momoe

29th Jan 2021, 10:32

Way beyond V1 and VR - airborne (https://aviation-safety.net/database/record.php?id=19980331-1)

vilas

29th Jan 2021, 10:57

These are just exceptions that only prove the rule.
That you must not reject after V1 is not disputable at all. It's as bad as saying A few get the multimillion dollars lottery so every one should come out of school and put all that money in buying lotto tickets. Never know!

Beamr

29th Jan 2021, 11:24

Some may find this an interesting read: https://code7700.com/pdfs/nlr_rejected_takeoff_after_v1.pdf

As a background: The complete sample encompassed 135 high speed rejected takeoff accidents and serious incidents. In 90% of these cases the aircraft could not be stopped on the runway. The statistical results are presented for the period 1980-1993 and 1994-2008 separately.

Based on the study while 100% of pilots believe that the RTO is the correct choice to be made on the occasion, in hindsight only ~32% of the RTO decisions were correct ones. However, ~44% are clearly bad decisions, leaving ~24% of the cases unclear.

Take what you will out of it.

olster

29th Jan 2021, 12:54

Reluctantly I will join the fray. The incident in question was not at night time. The weather was fine (no thunderstorms). To reject a take off after V1 is wrong as per both main manufacturers guidance, backed up by industry and regulation. As already pointed out, rto beyond V1 in the simulator will end in repeat, retest or fail. Why? Statistically go minded has been proven the safer option as per Boeing FCOM / FCTM / QRH guidance material. But hey, what do they know compared to the armchair experts who have already proven that they are unaware of the industry definition of V1. It is not decision speed as previously understood from the 90s.

The report has been translated from another language and there are some ambiguous issues through translation. The accident report does not say that the decision was correct. National air accident reports are compelled not to apportion blame. It was the captain’s view post event. To reject post V1 and even then not conduct the rto properly is not role model performance even though apparently it is offensive to call it incompetent. Go figure.

I am only contributing in order to correct all the misleading rubbish that appears here. In the unlikely event of a current younger B737 pilot reading this and debating even in their own mind whether it is acceptable to reject post V1 because of an incident in an HS748 at Stansted 30 years ago.Dangerous and misleading. I have got 25 years of flying B737s and been a TRE for 27.Also flown out of KTM many times. Sorry for the willy waving but I just want to emphasise that the report describes an incorrect manoeuvre. I do not want to hang out the PIC to dry; we all make mistakes and we can learn from them. Cheers.

alf5071h

29th Jan 2021, 15:15

olster, et al, your concerns reflect mechanistic modern industry, the expectation of unambiguous situations, decisions which can examined without bias, and only one 'right' outcome vice being 'wrong' in so many ways.
This is not the real world; operations are uncertain, and as much as we try to remove uncertainty with rules and procedures, the unachievable ideal remains embedded in our imagination.
^^^
Re the 748; context is everything. The good outcome - an innovative violation, providing opportunity to lean.
Alternatively a poor outcome, 'blame' - because the LP fuel cock was not turned off in the fire drill ('read the report'), opportunity to learn.
^^^
'Risk is the amount of uncertainty we have to manage'.
Intelligence:- the ability to manage uncertainty; to learn from experience.
… an ability to adapt to the environment. People who are intelligent can learn, reason, solve problems and make decisions that fit their real-life circumstances.
… is something that you can change through life. It is constantly updated by your interactions with your environment.
Real world problems:-
Are for high stakes, sometimes life-changing ones
Are emotionally arousing, to the point that emotions often cloud people’s better judgement
Are highly context-driven, requiring people to balance many conflicting interests
Lack a single “correct” answer
Lack any indication that there even is a problem; or else, the nature of the problem is unclear
Need a collective solution, often by people with different backgrounds and interests
Offer only vague paths to a solution, or seemingly no good paths at all
Unfold and need to be solved over long periods of time (but time is limited)
Make it hard to figure out what information is needed or where that information is to be found
Come riddled with numerous bits of false or misleading information, sometimes deliberately posed to make a valid solution more difficult
Solving such problems requires a mixture of creative, analytical, practical and wisdom-based skills – the foundation of the notion of adaptive intelligence.
Adaptive intelligence is relevant to solving complex problems in the real world. It consists of four main skill sets: creative thinking, analytical thinking, practical thinking and wisdom (the quality of having experience, knowledge, and good judgement).
An extract from New Scientist - Essential Guide to AI.

Humans must not be evaluated with mechanistic analysis after the event.
The real world is not If-Then; it is full of exceptions,
Except Pull Up, … !

MikeSnow

29th Jan 2021, 15:20

I searched the ICAO database ( https://www.icao.int/safety/iStars/Pages/Accident-Statistics.aspx ) for accidents with fatalities related to takeoff in the last 13 years, as the database only contained accidents since 2008. This is what I found that may be somewhat relevant to this discussion:

Crash: Avient Aviation MD11 at Shanghai on Nov 28th 2009, overran runway on takeoff (http://avherald.com/h?article=423638d8) - 3 fatalities

The crew did not properly operate the thrust levers so that the engines did not reach take off thrust. The aircraft had not reached Vr at the end of the runway and could not get airborne.
[...]
The crew members perceived something was wrong. Audibly the engine sound was weak, visibly the speed of the aircraft was low, tactically the pressure on the back of the seat was weaker than normal. Somebody within the crew, possibly on the observer seats, suggested the aircraft may be a bit heavy.
[...]
When the aircraft approached the end of the runway several options were available: reject takeoff and close the throttles, continue takeoff and push the throttle to the forward mechanical stop, continue takeoff and immediately rotate. The observer called "rotate", the captain rotated the aircraft. This shows the crew recognized the abnormal situation but did not identify the error (thrust levers not in takeoff position) in a hurry but reacted instinctively only. As the aircraft had not yet reached Vr, the aircraft could not get airborne when rotated. As verified in simulator verification the decision to rotate was the wrong decision. The simulator verification showed, that had the crew pushed the thrust levers into maximum thrust when they recognized the abnormal situation, they would have safely taken the aircraft airborne 670 meters before the end of the runway. The verification also proved, that had the crew rejected takeoff at that point, the aircraft would have stopped before the end of the runway.

Accident: Bek F100 at Almaty on Dec 27th 2019, lost height shortly after takeoff and impacted building after two tailstrikes (http://avherald.com/h?article=4d127dc6) - 13 casualties

The captain decided only the elevators were to be de-iced. The aircraft departed runway 05R, engines and systems were all working normally. The aircraft rotated and became airborne at 07:20:36L at 148 KIAS. The aircraft reached a maximum height of 20 feet, rolled right to a bank angle of 5 degrees, rolled left to 18 degrees left bank angle and rolled right again to 14.5 degrees losing height, the pitch dropped from 16 degrees nose up to 4 degrees nose down and went up to 14.7 degrees nose up again, the aircraft contacted ground, climbed to 6 feet AGL again, pitch reduced to 5 degrees nose up, the aircraft descended to the ground again, speed decaying reaching 129 KIAS, while on the ground the airspeed recovered again to 148 KIAS, the pitch increased 19.6 degrees, the aircraft climbed to 11 feet AGL, the gear was retracted, the aircraft lost speed again reaching 130 KIAS, pitch dropped 1.6 degrees nose down and the aircraft impacted ground a last time.
[...]
After commencing takeoff the aircraft became airborne but began to roll left and right, the left wing tip touched the runway. The aircraft sank back onto the runway. The first officer called to reject takeoff and retarded the thrust levers, the captain called "no need", advanced thrust levers and continued takeoff stating "Let's go, Let's go!". About 7 seconds later the commander instructs gear up, in the following the aircraft touched the runway 6 times with the tail, 4 times with the landing gear and one time with the wing.

Crash: NOAR L410 near Recife on Jul 13th 2011, lost height (http://avherald.com/h?article=43fa03da) - 16 fatalities

The captain briefed before engine start, that in case they had an engine failure above V1 and the landing gear not yet retracted, considering the length of the runway of 3100 meters, they might still abort takeoff and put the aircraft down onto the runway again. The aircraft was accelerating for takeoff from Recife's runway 18 when the left hand engine failed and lost power just at rotation. The first officer called to reject takeoff three times, the commander responded there was insufficient room to stop the aircraft and instructed to retract the gear. The first officer complied with that instruction only 50 seconds later after the captain had repeated the instruction for the 4th time. The captain instructed the first officer to request a return to runway 30 three times without realizing the runway layout of Recife had runways 18 and 36. The first officer advised ATC they would return to runway 36. The captain instructed the first officer to feather the left hand propeller, the propeller had already feathered however.

Automatic warnings "Do not sink!" and "Too low, Terrain" sounded. The captain again requested the left hand propeller to be feathered, the first officer responded the propeller was already feathered. The first officer requested to return to the aerodrome, the commander responded he was already turning.

The stall warning activated, the first officer requested to lower the nose, GPWS sounded "Do not sink!" and "Too low! Terrain". The first officer called "120 feet", the stall warning activated again. The first officer again requested to lower the nose and asked whether the captain wanted to land on the beach which met a categoric no. The first officer radioed they would land on the beach, the captain again denied, the first officer argued they would hit the top of the buildings, the stall warning activated continuously for 19 seconds, "Too Low! Terrain" and "Do not Sink!" sounded and the aircraft impacted the beach.

Crash: Ababeel IL76 at Khartoum on June 30th 2008, hit ground immediately after takeoff (http://avherald.com/h?article=408f9862) - 4 fatalities

The Sudanese CAA stated in their preliminary factual report, that the crew attempted to reject takeoff and hit the brakes, but it was too late and the crew pulled the airplane up below the required takeoff speed. The airplane was seen nose high after liftoff, then started a sharp left turn without gaining height and continued banking to the left crossing the North East Part of the Green Square, then lost height until impact with the ground. The impact occured with a nose down attitude of 30 degrees and a 60 degrees left bank.

alf5071h

29th Jan 2021, 15:38

Mike, the examples are not relevant because of either prior mistakes; i.e. as per 'spoiler'; mis-set thrust, no flap, icing check, which should have been identified before commencing takeoff, or because of system failure after take off.
These do not related to situation assessment and decision making at a critical point during takeoff.

excrab

29th Jan 2021, 15:51

I apologise, Olster, but the first part of your post makes no sense to me. You say the incident wasn’t at night, but the report states that it happened at 1621z, or 2205 LT, so it most definitely was night, being about 3 1/2 hours after sunset. You also say the weather was fine, with no thunderstorms, but we can’t draw that information from the report. It states that both crew members were aware of the bad weather in Kathmandu, and the latest METAR given in the report was at 0820, eight hours before the incident occurred, so totally pointless as far as the report is concerned. Even if they had included a weather report at the time just because it’s fine at VNKT doesn’t necessarily meant it’s fine in the valley between GURAS and the KTM. So I don’t see how we can discount the fact that the PIC may have had bad weather in his mind when he decided to reject, just from that report.

You also mention the HS748 crash at Stansted. This has, as you say, no relevance to the accident at Kathmandu, as at Stansted they didn’t reject above V1, they got airborne and then landed straight ahead on the remaining runway. However I think it is very relevant to the subject of simulator training, emergency drills and decision making. Had they continued into the air and carried out the standard drills and requested vectors back to land at Stansted they would have been airborne probably for fifteen minutes, and had the fire not gone out maybe the wing would have failed structurally. Maybe it wouldn’t, no one will ever know, but what we do know is that as a result of the Captains decision that night everyone walked away from it, and the AAIB report stated that the decision was sensible in the circumstances. Personally I think that every pilot be they young or old, flying 737 or any other type should be aware of that accident, and think outside the box. It’s really easy to say that in the simulator rejecting after V1 will require a retest, so we should never do it. But when we are accelerating down the runway, passing 150 kts and above V1 and suddenly something happens that makes us think that the aircraft is unsafe or unable to fly should we never stop? In a 737 on a 2000 metre runway probably not. But on a 4000 metre runway when we’ve got 2500 metres of it still in front of us, why not ? Real life isn’t the simulator. In real life we can’t be certain of the outcome of a scenario because we know what failures we’ve programmed, what speed we’ve armed the engine failure at, whether the fire will extinguish on the first bottle, or the second, or not at all ?

olster

29th Jan 2021, 16:26

I don’t really want to get involved in further debate on this. You are either in the industry and understand how performance works or you are not. It should appear obvious that you have to have a set of rules and understanding how go / no go decisions are made. The HS748 incident is not relevant in this context nor really any of the other examples. The general view here is that we have to have endless debate with a kind of free for all over the reject decision. Is that what we want or is it better that we have rules and regulations that determine how we perform in certain non normal situations? Statistically it has been proven beyond doubt that approaching V1 to be go minded. Both Boeing and Airbus promote this and indeed it is rubber stamped by regulation. Also both manufacturers in different ways reduce the reasons for reject in the high speed regime. Whether you like it or not rto twice at V1 plus on a recurrent check under any regulatory regime and you can hand your licence in on the way out. The rules are there for a purpose. They are not made up arbitrarily. What I don’t like is the intimation that we don’t have to follow or understand the technicalities of take off performance, what V1 actually means and we can find our inner Sully and use our self proclaimed superior skills and intellect for non normal scenarios. Dangerous stuff. I might add, the incorrectly performed rto in this instance, beyond V1 might not have had such a happily casualty free outcome at other airfields.

excrab, you are right on the time of day. There is a confusing mismatch between the metars and the take off time which I misinterpreted. The weather was relatively benign. and although nighttime my views on this incident remain unchanged. Finally, I have spent one dimensionally my career in the real world since the late 70s and understand real world dynamics. I have been @ V1 @ night @ KTM. I am empathetic to the crew and I am not here to castigate but we also have to be honest and realistic. Cheers.

FullWings

29th Jan 2021, 16:50

I agree with the above posters that it is not as simple as it sounds. When was the last time you were given a sim exercise where you had to reject after V1 in order not to crash? So, strangely enough, don’t reject after V1 in the sim!

Back in the real world, having an unexpected situation develop around V1, we don’t know in the case under discussion exactly where, leaves you in the position where rote behaviour (V1 = GO) is now at odds with cognition (can we fly?). I’m not a behavioural scientist but I don’t think you have to be one to realise that there is an awful lot of human factors here, not least the way we process information and make decisions, especially with conflicting inputs. I’m going to be controversial and say that one of the major causal factors here is a configuration warning that doesn’t appear to be inhibited at high speed - what’s the point of having it sounding if the consensus is that you should continue anyway? All it provides is an opportunity for confusion. On later aircraft, config warnings are inhibited approaching V1.

Statistically, it’s better to continue pretty much all of the time, so that’s what we train and what we expect to do. However, there is the possibility that one of us reading this thread may be dealt something truly nasty at some point in their career, like a multiple birdstrike at speed that causes multiple engine problems. Then you have to make a decision rather quickly...

PEI_3721

29th Jan 2021, 18:03

FullWings, you observe two important points.

First in simulation; either the situations are not sufficiently challenging, or that we behave differently in a simulator than we might in reality. Probably some of each.
Simulators are not reality; pilots in reality may not meet the imagined reality in SOPs.

Second, that the technology in more recent aircraft reflects what is now taught and accepted as good practice.
Investigations into incidents in older aircraft should consider these later standards. It would be impracticable to expect that older aircraft be modified to the latest standard, but at lest the errant config alert could be improved to work as designed.

hans brinker

29th Jan 2021, 18:41

olster

Sorry, but I have to disagree. In the SIM you get the same canned exercise year after year. I have 20 years of flying, and have never seen a reason to abort a fter V1, especially in the SIM. But I have landed on a runway covered in geese at night, and I struck a few in the flare. Had it been during take off there is a good chance I would have lost both engines. Dual engine failure after V1 is never trained in the SIM, to enforce the habit of aborting, because it is correct 99.9% of the time. But it is not correct 100% of the time.

sheppey

29th Jan 2021, 23:25

Dual engine failure after V1 is never trained in the SIM

I have often wonderd why not. I don't mean near the ground but at high altitude where double flameout in a thunderstorm has occurred. Garuda 737 for example. The drill in the QRH calls for a re-start and hopefully one engine always re-lights. Now your troubles are over - end of exercise and box ticked.

But what if you are unable to get both engines going? Boeing avoid that situation and leave it to the pilot to use good airmanship (or is that NTS 1,2,3 or 4?) On the other hand full marks to Airbus. At least their QRH or whatever it is called in that aircraft, leads you into a forced landing with all its additional hints.

I have yet to see a Boeing simulator demonstrate a dead stick landing. He wouldn't have a clue anyway. if a dead stick landing is allowed by a keen instructor it becomes a "fun" exercise like a barrel roll rather than a serious session. Thread drift apology

Stuka Child

30th Jan 2021, 00:19

Stuka, I'd like to see that.
Years ago, Boeing did a study of exactly that (aborting above V1 vs. continuing) and concluded just the opposite. The percentage of aborts above V1 which resulted in "catastrophic" outcomes was quite high (catastrophic being hull loss and/or multiple fatalities), where as cases where the aircraft was "unflyable" were extremely rare.

Now I'm not 100% sure we are thinking of the same thing, but I believe you are misremembering. What the study showed was that a high percentage of high speed RTOs were unnecessary and/or unjustified, versus the smaller percentage of correct calls. Pretty sure there weren't that many catastrophic outcomes.

There are many post V1 aborts that happen regularly. Much too many to list here. Of these, a number of instances result in overruns. Again, very long to list and I don't currently have a precise number, so I'd rather not say. A small number of these overruns result in fatalities. This is where we can actually dive into some figures.

This is the list of fatal accidents resulting from a high speed RTO, starting in 1980 (this includes aborts after being airborne, and I’m including even stuff like trying to take off from a taxiway or engaged parking brakes, taking forever to accelerate, etc.):

- JULY 1982: Philippine Air Lines 480, HS-748 at Yolo, 1 fatality out of 30
- SEPTEMBER 1982: Spantax 995, DC-10 at Malaga, 50 fatalities out of 394
- JANUARY 1986: VASP 210, Boeing 737-200 at Sao Paulo, 1 fatality out of 72
- JUNE 1986: Aeroflot, Tu-34 at Penza, 1 heart attack fatality out of 59
- JUNE 1989: Interflug 102, Il-62 at Berlin, 21 fatalities out of 113
- SEPTEMBER 1989: USAir 5050, Boeing 737-400 at New York, 2 fatalities out of 63
- APRIl 1990: Lao Aviation, An-24 at Luang Namtha, 1 fatality on the ground
- JULY 1992: China General 7552, Yak-42 at Nanjing, 107 fatalities out of 126
- SEPTEMBER 1993: Chaillotine Air Service, Falcon 10 at Besançon, 2 fatalities out of 3
- DECEMBER 1995: Chilean Military, CASA C-212 at Rancagua, 1 fatality out of ?
- JUNE 1996: Garuda 865, DC-10 at Fukuoka, 3 fatalities out of 275
- AUGUST 1998: Cubana 389, Tu-154 at Quito, 70 fatalities out of 91 + 10 on the ground
- MAY 1999: Kenyan Air Force, DHC-5 at Mandera, 1 fatality out of ?
- NOVEMBER 2000: Malu Aviation, An-32 at Luabo, 2 fatalities out of 11
- APRIL 2002: SELVA, An-32 at Popayan, 3 fatalities out of 8
- NOVEMBER 2003: Congolese Air Force, An-26 at Boende, 20 fatalities out of 24 + 13 on the ground
- JANUARY 2007: RAE 7755, Fokker 100 at Pau, 1 fatality on the ground
- JULY 2011: Missinippi Airways, Cessna Grand Caravan at Pukatawagan, 1 fatality out of 9
- MAY 2014: Private, Gulfstream IV at Bedford-Hanscom Field, 7 fatalities out of 7

TOTAL count: 317

So let's contrast that with loss of control accidents. Here are some fatal accidents where the crew decided to force the takeoff in an unsafe aircraft (non-exhaustive list this time, just want to give you an idea of scale):
- JANUARY 1982: Air Florida 90, Boeing 737-200 at Washington, 74 fatalities out of 79 + 4 on the ground
- DECEMBER 1985: Arrow Air 1285, DC-8 at Gander, 256 fatalities out of 256
- AUGUST 1987: Northwest 255, MD-82 at Detroit, 154 fatalities out of 155 + 2 on the ground
- AUGUST 1999: LAPA 3142, Boeing 737-200 at Buenos Aires, 63 fatalities out of 100 + 2 on the ground
- JULY 2000: Air France 4590, Concorde at Paris, 109 fatalities out of 109 + 4 on the ground
- NOVEMBER 2000: ASA Pesada, An-24 at Luanda, 57 fatalities out of 57
- SEPTEMBER 2005: Mandala 091, Boeing 737-200 at Medan, 100 fatalities out of 117 + 49 on the ground
- AUGUST 2008: Spanair 5022, MD-82 at Madrid, 154 fatalities out of 172
- MAY 2018: Cubana 972, Boeing 737-200 at Havana. 112 fatalities out of 113
- DECEMBER 2019: Bek Air 2100, Fokker 100 at Almaty, 12 fatalities out of 101

The entire number of people killed by takeoff overruns over a period of 40 years is equivalent to 2-3 LOC accidents. None of these lives should have been lost, and each and every one matters.
But if an accident is inevitable, I hope you can see which one will give you the best chance of survival.

(*main source: You can find them all in the Aviation Safety database, no matter the size of the aircraft. You just have to know how to search. The ones I was unfamiliar with I validated by going through the reports, just to make sure that they fit the criteria)

Conclusion: Yes, everyone knows we should be go-minded at V1. But that does not mean go at any cost. I see some of you saying, "oh you should never be in that situation anyway, these accidents were all preventable if they had made the right calculations, set the stab trim correctly, set the flaps correctly, etc etc.". But that matters zero! If you somehow find yourself in that situation, whether it's a wonky weight & balance, or wrong flaps setting, or ice or fire or a satanic force holding you by the gear, if you judge loss of control or structural failure are imminent, or that you cannot clear whatever obstacle you will be flying towards, you take the goddamn overrun!

Icarus2001

30th Jan 2021, 03:54

These do not related to situation assessment and decision making at a critical point during takeoff.

V1 is the decision.

It is simply impossible to "make a decision" about the flyablility of the aircraft after V1. That is why we have V1.

This crew were "lucky". Some crews are unlucky.

alf5071h

30th Jan 2021, 09:52

I bother because I am still learning.
“You are either in the industry and understand how performance works or you are not.”
Re 'industry', a yes-no answer.
Re 'understanding', an opinion, after the event, without assurance that my opinion or that of others is correct, at that time, in that situation.
Re 'performance'; for aircraft a simple yes-no, a line on the page.
Re 'performance' relating to people; this defies explanation, too many variables, thought, context, situation, etc; thus the use of Behavioural Markers, ratings, not numbers.

Consider a jump-seat CRM check-ride for this incident. You rate the crew at the moment the aircraft stops, as a crew member; a judgement call either way - but you are going to walk away.
Consider the same scenario in a simulator; a decision for a pre-programmed event chosen by you, where the outcome is known (one way or another) and can be judged (rated) yes-no.
Consider now, penning words to Pprune, with incident report and FDR to hand; another rating.
If these ratings differ, why.
If they are the same, why; which is easier to explain … and why.
Why do I bother, because its another opportunity to ask why, hoping to improve understanding.
Learning from the misfortunes of others.

olster

30th Jan 2021, 10:43

Cheers George. I don’t know what happened to your post. The only reason I engaged at all is because the misinformation and lack of basic understanding masquerading as expertise is very dangerous and misleading. There are obviously very few professional pilots here but nevertheless everyone has an ‘opinion’. It is not up to me who contributes to these threads but it was optimum when those who knew what they were talking about posted.

Assuming you are in Australia, hope you are easing out of lockdown safely.

ManaAdaSystem

30th Jan 2021, 10:46

Icarus2001

Well, if the aircraft doesn’t fly after V1, it’s unflyable.
I’m a firm believer in the V1 consept, but I also believe in Murphy.
«That can’t happen» doesn’t apply to me,

Momoe

30th Jan 2021, 14:28

Surprised that no-one has mentioned flex take offs as a contributory factor.

There have been some serious brown trouser moments when flex calculations have been incorrect, even a correctly calculated flex take off gives less runway if something goes wrong. I can't find statistics on flex related accidents but I'm certain that the bean counters win with increased time on wing and maintenance costs for engines.

Semreh

30th Jan 2021, 14:29

I don't have the statistics to hand.

I would hope the relevant authorities do have the statistics to hand.

The official advice given about when to attempt a no-go after V1 should be followed. Such advice is normally generated by people's deaths. Discussing individual cases is pretty fruitless as what is important are the overall statistics and the criteria by which the statistics are judged. If you want to criticise that method from a position of knowledge, go ahead: but using individual cases to argue a point isn't really helpful due to all the biases involved, most of which are unwitting.

The other things to remember are that:

(a) Hindsight is a wonderful thing, beloved of 'armchair quarterbacks' the world over. Analysing a situation from the relaxed position of having enough time to think things through and being in possession of the relevant facts is vastly different to making a decision in the heat of the moment.
(b) Simulators are artificial. You know you do not have a bus-load of souls behind you. You end up treating things in a different way, some better, some worse.

There is room for individual decision making. As a captain you have that right, which also has a heavy responsibility. There are times when declining to follow the official guidance is the right thing to do, and if you get it right, you might be a hero, and if you get it wrong, you will be responsible for bad things happening. Rules are for the guidance of wise men, and wise men know their limitations.

olster

30th Jan 2021, 14:49

My final word on this subject. It may come as a big surprise that simulator instructors / examiners are also real world pilots (including me) and very aware of both their responsibilities and real world scenarios. Simulators are regulated to a very high fidelity and are not toys. You may not lose your life in one but you can certainly lose your licence. Rules in commercial aviation are defined by regulatory authority and are not merely for guidance but adherence that is if you wish to remain employed. Nobody is a hero and in professional aviation we just try to do our jobs properly and recognise if they are not. It’s called professionalism based on years of experience and study. The only reason I have engaged is to dispel the dangerous misinformation and lack of even basic understanding of jet transport performance displayed in many of the posts here.

Stuka Child

30th Jan 2021, 14:56

Semreh

No it is not. It is generated by statistics showing that usually when rejecting above V1, the PIC gets it wrong and does so for an insufficient reason. However, those same statistics show that in a smaller proportion of these cases, the abort was actually justified! That should be the end of the debate right there! Another member posted one such study several posts up. Look it up.

As for individual cases, I just enumerated them so you can see the severity of the accidents vs loss of control on takeoff accidents. These are the actual numbers - 317 human lives lost in 40 years from high speed aborts - and we're talking everything from V1 to x knots above Vr. We're talking cases where the aircraft got airborne twice and still they rejected and the net result was better almost every time than continuing with a non-flying aircraft. If you don't believe me, do your research.

As for the members accusing everyone who doesn't agree with them of being flight sim drivers, that's just disgusting. If you wanted to see some credentials, you could have asked in a civilized manner over PM.

This is the last time I participate in such debates. Take your chances on the ground or take your chances in the air, in the end you alone will be judged for your actions.

B2N2

30th Jan 2021, 16:15

Take your chances on the ground or take your chances in the air, in the end you alone will be judged for your actions.

I’ll take my chances on the ground thank you.
What is indeed disgusting is the pedantic attitude and the cherry-picking.
Its been said already and I’ll repeat it, he buggered up the RTO.
To focus solely on the reason for the RTO is not seeing the entire picture.

“Airplane unable or unsafe to fly”
Now they had no annunciation but have a read and consider rejecting after V1 and going off the end or taking it “flying”

https://aviation-safety.net/database/record.php?id=20181111-0
Similar event: (https://aviation-safety.net/database/record.php?id=20181111-0)
https://www.dw.com/en/german-government-jet-suffers-serious-damage-in-crash-landing/a-48403681

Now sit back in your armchair and reconsider the above two examples in some of the highest mountainous terrain in the world...at night...with weather. (https://aviation-safety.net/database/record.php?id=20181111-0)
I’d be more then happy going off the end in these cases.
I’ll even shred my license as I’m walking away from it.

Big Pistons Forever

30th Jan 2021, 17:04

To focus solely on the reason for the RTO is not seeing the entire picture.

There has been a lot of back and forth on this thread and from my POV, posts that seem more directed at "winning" the argument than contributing to expanding understanding of what and more importantly WHY this event happened.

I like reading PPRUNE because there are often ideas expressed that force me to challenge my assumptions on important issues. And numerous times I have been forced to reconsider things I thought were obvious and not worthy of debate.

B2N2's, quote above, to me, really summarizes the issue.

When I first read the report I have to admit my first thought " Oh Yah some third world crap airline went off the runway after they totally pooched the RTO and this would never happen to me", then I thought of a takeoff I did at Terrace British Columbia (CYXT) one really, really nasty night. We had a long discussion about getting out of the valley if various bad things happened but they were all considerations for after we got airborne. The part from max power to V2 was just the standard brief. I remember letting go of the brakes after the stable power call and thinking only about getting safely out of the valley. I like to think if a similar issue ( i was not flying a 737) had occurred I would have acted perfectly but thinking back I am now not so sure. You can be mentally behind the airplane but you can also be mentally too far ahead of the airplane.

From a human factors POV I think this was a significant factor in this incident. Combine the mental model the captain had at the beginning of the takeoff roll flying out of a very challenging airport, with evidence of incomplete/poor training and you have this result. Even in reputable Western airlines there has been constant pressure to reduce training costs which has IMO led to a very tick the box culture developing in sim training sessions. So if all the boxes are ticked the pilot must be fully trained, right ? This would never happen to a us flying for a real airline, right ?

Finally I think it is worthwhile to acknowledge that after the aircraft came to a stop there was some good CRM happening. This could easily have turned into a full evacuation with probable injuries if he FO had not made some good recommendation to the Captain which the Captain accepted.

The take away for me, and I think it is important to note this is a personal take away not advocacy for a particular action as the "right way" to do things; Is a reinforcement that regardless of the situation, when the power levers go up the importance of having my brain engaged totally on what is happening from now to Vr, not on what might happen later in the departure.

tdracer

30th Jan 2021, 19:20

Stuka, you're missing the point. On the above list, on how many did the crew learn of something after V1 but before they attempted to rotate? Most of those the aircraft were not flight worth at the beginning of the takeoff run (generally mis-configured with an inop or disabled warning system). If the aircraft won't rotate, you're generally not going to discover that until you attempt to rotate - at which time you better pray there isn't much to hit at the end of the runway.
The only one that really fits the scenario of the crew getting some sort of indication of trouble after V1 is Concorde - and they were going so fast when the tire blew that even if they'd tried to abort I doubt it would have ended much better.
The question is, should you abort if you get an indication of a problem after V1. The Boeing answer was no...
Pointing out that aircraft that are not airworthy at the beginning of the takeoff run often crash is a non sequitur.

Semreh

30th Jan 2021, 21:35

Stuka Child.

I hope you continue to participate - your knowledge, experience and opinions are valuable and worth sharing.

Beamr posted a link to an interesting (and I hope, informative) study: NLR Air Transport Safety Institute: REJECTING A TAKEOFF AFTER V1...WHY DOES IT (STILL)HAPPEN? (https://code7700.com/pdfs/nlr_rejected_takeoff_after_v1.pdf)

The inclusion criteria for data analysis were:

The following criteria were used to establish the data sample:
•Only occurrences that were classified as ‘accidents’ or ‘serious incidents’ according to ICAO Annex 13 definition were included;
•Both fatal and non-fatal accidents were included;
•The accidents and serious incidents involved a high speed rejected takeoff in which the abort was started after V1 (the actual decision to abort could be before V1);
•Accidents related to unlawful or military action were excluded;
•The occurrences involved fixed wing aircraft with a maximum takeoff mass of 5,500kg or higher that were used in a commercial operation (passenger or cargo) including training and ferry flights. There was no restriction to the geographical location of the occurrence;
•Both turbofan and turboprop aircraft were considered. Piston engined aircraft were excluded; •The accidents occurred during 1980 through 2008.

As far as I am concerned, the inclusion of fatal accident data means that the data are generated from peoples' deaths. Hard won statistics.

Note that I am not saying one should never abort after V1. Obviously, things are far more nuanced than that, and as the report linked to by Beamr says:

•Pilots have difficulties in recognising “unsafe to fly” conditions;
•The Detection-Decision-Action process still takes a lot of time!

Despite these difficulties, in the period 1994-2008, for the incidents analysed, 31.9% of the decisions to abort were correct (44.4% were not, with the remainder unknown)

I have neither the experience or knowledge to evaluate what happened in Kathmandu, and the multiple opinions in this thread show that it is not cut-and-dried. What we know from statistics is that many RTOs are unjustified. Some, however, are not, and we are arguing/debating/discussing how to tell the difference. It isn't always easy.

I'll thank you again for your engagement. I think we are on the same side, but maybe on different wings (football, not aircraft).

Stuka Child

30th Jan 2021, 23:08

Semreh,

I am sorry if I came across as confrontational. I apologize for that, it was never my intention to write as if we were arguing. My "steam" was mostly directed to a particular set of posters who insisted dogmatically that to even contemplate aborting above V1 meant you don't know what you're talking about, you are not in the industry, etc.. You are absolutely right that people have indeed died in these tragic accidents, and sometimes looking at numbers and statistics one forgets that these were actual beings with their own inner universes, with their own emotions, and that is something that cannot ever be measured. Even one fatality is too much.

I guess what I'm trying to do here is to churn up some ideas that we can all maybe think about in order to at least increase the chance of survival if - God forbid - we are confronted with such a situation one day. As you said, 31.97% of high speed RTOs in that study were judged correct. That is a mighty high percentage, which in itself completely disproves the notion that V1 means continue at any cost. Now, as you say, how to tell the difference between something catastrophic is happening vs. I can fly this? Or between this plane is never getting off the ground (or will only come down harder if it does) and let's just grab some more airspeed and hope? In the heat of the moment, it is a nasty choice to make, knowing that you might kill people either way. Only thing we can do is be prepared - knowing the airport, knowing the aircraft and having some personal criteria set down. Beyond that, it's just instinct. Could turn out right, could turn out wrong.

For the incident at hand, I can understand why the Captain made this decision and even the relevant authorities are in agreement. Just to get a visual idea, this is the outcome:

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/512x341/malindo_overrun_bb8e4638fc825486850ec3a798242022ac59fc3b.jpg

No injuries, aircraft is fine, and keep in mind this was not a properly executed RTO.

Thank you for keeping the discussion going, I think there is great potential for all of us to increase our understanding.

tdracer

The point remains the same, whether something catastrophic happens after V1, or whether you realize as you try to rotate that your aircraft won't get off the ground, or that if it does it will only be controllable for a short time. The fatality rates are clear: if an accident is bound to happen one way or the other, you drastically increase everyone's chances of survival by staying on the ground and slowing down as much as possible before you hit whatever is in front of you VS. forcing her up into the air and hoping she'll go and starting to hit stuff with the engines running at takeoff thrust or pancaking it in from the sky. I'm not saying it's an easy call to make. But it is something to think about.

If you have time, look through the accident reports as I have and also through some of the non-fatal incidents. Many of these high speed RTOs were obviously wrong calls. If they had continued, everyone would have lived. But there were quite a few right calls as well. And I'm talking rejecting well after rotation, forget about V1.

Think of it this way. You are in what you believe to be an unflyable/uncontrollable aircraft as you are rotating or trying to. If you take your chances on the ground and get it wrong, you will kill 16 people on average in case of a fatal accident. A common number is between 1 and 3 fatalities. If you take your chances in the air and get it wrong, you will on average kill almost everyone on board in case of a fatal accident. These are the stakes.

Fursty Ferret

31st Jan 2021, 08:38

I have no issue at all with the crew's decision to reject the take-off. They received an unambiguous indication that the aircraft wouldn't fly safely but were hamstrung by the fact that they were in, essentially, a 50-year-old aircraft with no further information about why that might be. If you gave me a config warning at V1 I'd be thinking about an uncommanded flap retraction, or speedbrake deployment, or trim runaway - all of which would lead to loss of control very quickly.

The aircraft would have stopped on the paved surface if they hadn't disconnected the autobrake, which is really the only learning point I'd take away from this.

Momoe

31st Jan 2021, 09:29

One of the unwelcome elements of PPRuNe is it's ability to polarise topics, which then creates factions, something this thread demonstrates very well.

Having taken a side, IMO it does reduce any objectivity. If you believe you can argue either side of the argument and still sift the wheat from the chaff, carry on.

What I do find ironic is that some of the go minded posters are also the one's who would criticise "Children of the magenta line"

safetypee

31st Jan 2021, 11:45

Stuka, focus on emotive fatalities can lead to unbalanced conclusions.
Historical risk, with known outcome and statistical probability is a measure of what happened, but more often not suitable for judging future risk requiring statistical inference. The future does not follow the past.
Past probability is not always suitable (e.g. 737 Max should not happen again).
Also, the outcome in future events is unknown, particularly fatalities - circumstance, aircraft size, passenger load, etc.
As in previous posts, there are very few if any actual 'catastrophic' (n.b. emotion) events after V1, but far more issues prior to takeoff.

A good comparison with this event is the CRJ overrun at Charleston - mis set flap, then config alert after the crew reselect during the takeoff. RTO after V1, saved by EMAS.
The outcome risk in each of the accidents appears similar, overrun mitigated by EMAS or 'mud'; but considering future risk - without mitigation, the difference between the steep drop off the end of 23 CRW, or more grass at KTM, would influence our judgement of 'risk' (likelihood of harm), … for an event which more likely is initiated before takeoff.
https://www.skybrary.aero/index.php/CRJ2,_Charleston_WV_USA,_2010
https://www.skybrary.aero/index.php/KCRW

momoe; the problem with the much quoted "Children of the magenta line" is that it fails to explain how we achieve the awareness and then decide to 'click click'; aspects central to this incident.

Background reading 'Decisions under Uncertainty'
https://www.farnamstreetblog.com/2013/11/decisions-under-uncertainty/
Follow the links to parts two and three:-
2 Two types of Ignorance; … we live in a world where we are, to some extent, ignorant, then the best course is “thoughtful action or prudent information gathering.” Yet, when you look at the stories, “we frequently act in ways that violate such advice.”
3 Avoiding Ignorance; … our “illusion of predictability.”

Also; a view of reality, situations and decision making are not clearcut, not black or white arguments.
Conditions for Intuitive Expertise 'A Failure to Disagree'
Under what conditions are the intuitions of professionals worthy of trust?
True experts, it is said, know when they don’t know. However, nonexperts (whether or not they think they are) certainly do not know when they don’t know.
http://www.hansfagt.dk/Kahneman_and_Klein(2009).pdf

Fortissimo

31st Jan 2021, 19:07

Stuka,

tdracer has a point, you are not comparing like with like. I have taken the time previously and again today to look at the cases you cite of "crews forcing an unsafe aircraft into the air..." and your argument only holds true if the pilots knew at the time that their aircraft was unsafe. The Northwest accident is a classic in this respect - there was no evidence to suggest the T/O Config warning was available, as the warning horn was not present on the CVR and the CB was found in the popped/pulled position; that crew would likely have been unaware there was a problem until the first indications of a stall, when the natural reaction is to try to fly your way out of it, not close the throttles and accept an over-run. Similarly with Bek Air (failure to de-ice) and the Havana B732. Throw in some startle and surprise, and you can expect people to try to make the circumstances fit the their mental model. Would any of those crews have known - without the benefit of hindsight - that an RTO was safer than V1? Would they have had time to think it through? I doubt it.

Centaurus

1st Feb 2021, 06:01

The uncertainity factor in stop or go situations is often critical. Particularly if the runway length is marginal and it is night time.

For example, I was jump seating when a Boeing 737-200 took off on a performance limited runway at night. That means a rated thrust bleeds of takeoff which usually means a real kick in the back at full power. At the far end of the runway was a road, then large boulders that formed a sea wall with a drop of 20 feet into the Pacific ocean. A motor bike policeman was stationed on the road to stop traffic until the airraft was airborne.

What we (the captain, the first officer and me as a pilot observer) did not know was that insects and blowing phosphate dust from a nearby phosphate mining area had already blocked the entrance to the Pt2 sensor situated at the front of the P&W JTD-17 engines. So when the first officer applied power to achieve 2.18 EPR at 101% N1 the captain took over the thrust levers and set 2.18 EPR. The engine instruments of N1 and N2 are quite small and the instrument lighting was set low because of the sheer black Pacific night.
In fact, although the EPR gauges showed the needles on 2.18 it turned out to be in this case, a false reading similar to the iced up Pt2 tubes of the Air Florida 737-200 that crashed into the Potomac River at Washington.

Passing one third of the way down the 5200 ft runway of this Pacific atoll, I had an uneasy feeling that the acceleration wasn't the kick in the back that I had been expecting. I leaned forward to get a better focus on the N1 gauges to confirm their readings agreed with the expected 2.18 EPR. I was not wearing my glasses at the time and it was difficult to see the exact reading of the needles of the N1 gauges because of the small graduations. The difference between 101% N1 and 90% N1 was about 4 millimetres.

As I was focusing on the readings of the N1 gauges, I noticed the captain was rapidly glancing ahead at the runway remaing then back at the instrument panel. I wondered if he had the same feeling of unease as me. With the end of the runway coming up fast, it suddenly dawned on me that we were never going to become airborne before the end of the runway - especially as the airspeed was was still approaching V1 with three runway lights to go. At the same time I realised we were in dire straits, the captain acted fast and taking over control from the first officer he firewalled the thrust levers forward against the mechanical stop and hauled back on the control column. . An abort at that point would have been fatal. There was an immediate surge in power as the EPR shot up to 2,30 EPR or thereabouts. . We cleared the threshold and the captain was immediately on instruments. What we didn't know was the jet blast blew parts of the road and sea wall boulders back over the threshold and along the runway. It had been a very close shave. . The policeman blinded by the aircraft landing lights coming closer had already seen the Boeing bearing down on him like an express train and had gunned his motor bike away from danger fast.

At a safe height the captain set standard 1.94 EPR climb power on both engines and commenced flap retraction. During the climb and after the flaps and leading ege devices had fully retracted, we accelerated to 280 knots climb speed. The rate of climb at 10,000 ft was much less than expected. A comparison of climb EPR versus N1 from the manual revealed the N1 was lower than expected;.as was the rate of climb. On a takeoffa few weeks earlier, I had experienced the effect of a single blocked Pt2 sensor which had cleared itself after application of engine anti-ice; even though the OAT was quite high at 25 C.

A simultaneous blockage of both Pt2 sensors at the sea level temperature of 30 C was something I had never heard of before. With both engine readings showing parallel to each other (including EPR and N1) during the takeoff and climb, it was not immediately obvious that we were experiencing a double Pt2 sensor blockage unless one was quick enough to take the N1 readings. Keeping in mind it was night and instrument lighting low.

The captain decided to return to land as the cause of the low rate of climb was not obvious at that point. Fuel contamination was suspected since both engines had identical readings. After touch down, normally 1.6 EPR is used for reverse thrust. I hinted to the captain to use full reverse against the aft stop in case the EPR was mis-reading because at least we knew we were obtaining full reverse. The landing was normal; as was the taxy in. On the ground, the cowls were removed and evidence found of insects and phosphate deposits in both Pt 2 sensors. Both sensors were totally blocked. Hence the subsequent EPR faulty reading. The engineers had forgotten to install covers over the engine intakes during an overnight stop.

Calculations made after the event revealed the actual EPR attained during take off was around 2.07 although both EPR gauges showed 2.18 EPR. A closer check of the N1 during the takeoff would have revealed a figure of around 90% on both engines instead of 101.5%. The fact that all engine readings were parallel to one another led us to believe that all was normal.

On the other hand, if only one Pt2 sensor was blocked it would have stood out as a significant split between the two sets of engine readings and thus the crew would have been alerted at the beginning of the takeoff roll and rejected the takeoff.at low speed. The lesson I took from that event was the difficulty of assessing remaing runway length to go at night and to use N1 as the prime thrust setting and not EPR if fitted.

Capn Bloggs

2nd Feb 2021, 08:41

May have been posted before but Reject after "rotate":

ASN Aircraft accident McDonnell Douglas MD-83 N786TW Detroit-Willow Run Airport, MI (YIP) (aviation-safety.net) (https://aviation-safety.net/database/record.php?id=20170308-0)

ManaAdaSystem

2nd Feb 2021, 17:48

I don’t think this situation was covered in his set in stone pilot manual, Steinar.
Or he could do what Pinestream said he did in the sim, TOGA and fly by trim. Except that would not have worked either.
What did the report say?

Contributing to the survivability of the accident was the captain’s timely and appropriate decision to reject the takeoff, the check airman’s disciplined adherence to standard operating procedures after the captain called for the rejected takeoff, and the dimensionally compliant runway safety area where the overrun occurred."

safetypee

2nd Feb 2021, 17:59

Re the MD83 RTO, #98
The report did not discuss the preflight control check. Would the fault be detectable before flight; it was at some point after flight. A similar servo-tab check on the 146 should have detected the stuck elevator, vice free tab; this check was difficult in a tailwind. The MD83 event discusses wind as causing the damage; similar aircraft have gust dampers, were these working.
Nor does the report consider the certification aspects of dual-path, split control systems, which require the ability to rotate and fly with a single system.

Steinar, 'What would you have done', I expect an honest answer would be that we don't know, because such decisions depend on the situation at the time, as assessed then and there; we were not there.
Questions answered with hindsight (as in the report, with outcome knowledge) might have little relevance to real world outcomes; explanations in the last link. https://www.pprune.org/showthread.php?p=10980286

FullWings

2nd Feb 2021, 22:21

If find it interesting that those most critical of this discussion, and it is only a discussion, have made no input to it apart from disparaging remarks and “I’m right and you’re wrong”, without presenting facts or any kind of rational argument. Not the way anyone I know who is actually involved in training (or any kind of endeavour) behaves, or should behave.

I don’t think I have seen any suggestion on this thread that rejecting at V1 or above is anything other than a last-ditch method to try and avert/ameliorate a major catastrophe. Most of us will go through an entire career without ever coming close to being put in this position, but there is always the possibility.

We have rules, regulations and standards in aviation to cover a lot of eventualities, with the caveat that when you find yourself in a situation outside the purview of the QRH, etc. you need to draw on all your knowledge and experience and those aforementioned rules become guidelines. It is understandable that those used to enforcing standards find this difficult to grasp, as it is not something which can realistically be trained or assessed. A scenario where the best result is a survivable crash, which is only possible through taking unorthodox action, is not something most would wish as part of an LPC/OPC.

There are a lot of shades of grey here. Taking off from 16L at DOH and birds go down both engines at V1+5, with pops and bangs from both sides with 3,000m+ remaining is a different proposition to a short, wet runway with a very wet or rocky overrun. Is there EMAS installed? Is the V1 we’re using at the high or low end of what is usually a spread? And so on. A good working knowledge of aircraft performance is very useful because it will give you some idea of what might happen if you have to bend/break SOPs through force majeure. Conventional performance is based on losing only one of your powerplants and the configuration of the aircraft being what was planned; as soon as any of those cease to be true, you are on your own and flight may become difficult or impossible.

Capn Bloggs

2nd Feb 2021, 22:31

Safetypee

Most of those points are covered in the NTSB report:

https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1901.pdf

jmmoric

3rd Feb 2021, 09:17

Some reading:

https://www.skybrary.aero/index.php/Rejected_Take_Off

https://tc.canada.ca/en/aviation/commercial-air-services/publications-guidance/multicrew-aircraft-standard-operating-procedures/723-abort-rejected-take

safetypee

3rd Feb 2021, 12:17

Bloggs, Thanks, #100
I have fallen foul of my own criticism of using incomplete or summarised, third party accident reporting.
I will reconsider the technical issues in the report, but initial reaction is that for most aircraft the control check is a true check, but there are still some which are not - grandfather rights (DC 9 - MD80).

For this thread, the 737 airbrake detent - Takeoff Config Warning; some aircraft better than others, where this 737 required special maintenance procedures, with additional risk of error.

The MD83 crew faced a no-win situation; something which the industry should not tolerate.
The contributing factors were avoidable providing later safety standards had been applied; they were not. Thus the safety responsibility - these who should bear the risk, lies with the regulators and manufacturers, not those last in the chain of events, the 'crew'.

The time history indicates a 7 sec period between Rotate and the Abort call; a measure of the difficulty in assessing the situation and deciding what to do.
No dispersions on the MD crew, they acted as they saw the situation, but for those in this thread who believe that it is possible to have instant awareness and decision making in these situations should reconsider human behaviour, particularly in rare and surprising situations.

This also applies to those who write SOPs, what is imagined to occur vs reality; who knew of the limitations of the control check.

It is better to consider the SOPs for RTO as only applying up to V1; thereafter Go.
There will be situational exceptions above V1, but not sufficiently imaginable for a SOP - nothing is Standard.
In these rare circumstances, requiring pilot judgement, the mindset should consider the action of stopping as only to reduce the effects an accident.

netstruggler

3rd Feb 2021, 12:27

safetypee

I agree. I remember attending a presentation at work on: Conscious and subconscious behaviours in a safety critical environment. One of the problems, I was told, is that, "In an emergency your subconscious tends to arrive first".

Flaps1Pls

6th Feb 2021, 04:06

Is there an airline in the world that trains , in License Renewals , Instrument Ratings etc. for rejected takeoff after V1 ?

PPRuNe Towers

6th Feb 2021, 16:42

As a test item no... As a training item yes - twice for me. Hydraulic failure was the simple switch method to create locked controls after V1.

Rob

Landflap

8th Feb 2021, 08:04

Rob, bet that training exercise was still a bit of a flatulence trigger though. Mine was (training), passed 80kts, rapidly getting to V!, Expecting the V1 call but FO briefed to feign death, or something. No call. J u s t got away with it .

Flaps1Pls

9th Feb 2021, 02:03

PPRuNe Towers

Hydraulic failure in a B737 does not stop you rotating at Vr.
There is a fine line between novel scenarios that enhance training and instructors own made up “ what ifs “ that lead you to doubt SOPs and sound judgement.
There is nothing achieved by putting trainees in unsurvivable situations.
There are many runways I operate out of where rejecting after V1 will result in going over the breakwater and into the sea.
Finito.
No point in training that.

PEI_3721

9th Feb 2021, 06:37

For those who use training scenarios after V1; would these result from a single systems failure in your aircraft.
Are these realistic 'aircraft unable to fly' situations, or just 'lets think of a situation'.
There is no training value in the latter, which could negatively influence crew's interpretation of real, but not critical failures requiring continued takeoff.
I doubt that any modern aircraft have any single, undetectable systems failure which results in the inability to fly.

Landflap

9th Feb 2021, 08:06

PEI 37: Drifting a bit, but ,
There is huge traing value in 'let's think of a situation' so long as it is kept in the classroom. After much debate, rigid reminder & enforcement over the principle, STOP before V1, GO after.would be the instructional aim.

In the Sim, again, "training" would involve enforcement of the rule.

FullWings

9th Feb 2021, 16:57

I would have thought running through scenarios where a V1+ stop is a good idea, then telling people NEVER to do it, might lead to a bit of cognitive dissonance in the recipients?

If there were unlimited time and budget for training, then you could start throwing one-in-a-million problems into the pot, but that is not what we have. Probably better to concentrate on things like raw data NPAs, rejected landings and conventional RTOs. ATQP, EBT, etc. focus on things that have relevance to the operation, some derived from FOQA/ASR.

I think it is the responsibility of any aircraft commander to have at least thought a little bit about what could drive a quick decision to abort >V1, and what the outcomes might be in different scenarios. I don’t think it’s something you can have SOPs for, as every day is different. If you get it right, you’ll be a hero, if you don’t, you might have to carry on walking. Luckily, the overwhelming majority of professional pilots won’t ever be placed in this situation, so we should have some sympathy for those who have been...

ManaAdaSystem

9th Feb 2021, 21:14

Agree, we all use the V1 concept every time we fly, but it doesn’t mean the world is black or white.
There are for instance cases where I will continue with failures from below V1. Rejects above V1 may turn out to be the only option.

Rwy in Sight

10th Feb 2021, 07:25

Wasn't here a thread about calling V1 early to assist with continuing the take off after a failure?

FullWings

10th Feb 2021, 10:43

You have to be a little careful with that as continuing below V1 can have consequences as bad (or worse) as stopping after. Vmcg, obstacle clearance and the like. As ever, it depends on the exact circumstances what the options and the result of taking one of those options are...

Big Pistons Forever

10th Feb 2021, 15:13

It is impossible to have a plan for every possible contingency for every takeoff. At the end of the day the situation where the Captain will have only a few seconds to decide what to do for an emergency will usually fall into the fairly obvious keep going category, but there will be the odd one where all the skill and knowledge acquired to get to that left seat will be called on to in maybe 2 or 3 seconds make a decision that will be very consequential.

The only defence we have is good training and effective line checking to keep standards up, something I would suggest was deficient in this airline.

Landflap

11th Feb 2021, 08:14

OK. Last effort. Fullwings, not difficult at all. Up to 80 kts, stop for anything, beteween 80 & V1 only for specific items, well rehearsed, well discussed, even here, big Boeing making it very clear, big airbus making it very clear,......after V1 ...................go baby go baby go, FFS ! Back to thread though, the KTM guy made the wrong decision" was very lucky to have got away with minimal damage.

SteinarN

11th Feb 2021, 09:27

Ok.
No thinking required, only follow predetermind rules, sounds good....
Now we can expand those no-thinking-rules to all parts of the flight, easy....
Then we have no-thinking for the full flight. We all know that computers are much better and more reliable than humans at executing no-thinking actions based on easy to follow rules....
We now can get rid of the humans in seat row zero. We save on salary since computers are much more reliable in executing no-thinking easy to follow rules. Accident rates should drop markedly....

FullWings

11th Feb 2021, 11:44

after V1 ...................go baby go baby go
That’s what we teach, train and by and large, what people do. What we’re talking about here is the possibility, small but non-zero, that this time the baby won’t go, or that there is serious evidence that it may not. The statistics appear to show, surprisingly, that we are not as bad as we think in making that judgement call, and that overruns are much more survivable than crashes. Should that change what we normally do approaching V1? No, of course not, but at least we should be aware of the above.

I would be right up there with the critics if this had been a rushed approach with many opportunities to throw it away and have another go; as it was, there was a config warning around V1, taking off hot-and-high from a terrain-constrained airfield. By the time you can positively ascertain what is causing it and how it is going to affect flight (or even allow flight at all), it would be too late, so a decision is required. The conflicting pressures of learnt behaviour in 'V1 must go' vs. 'config warning must stop' (as it will have been almost exclusively trained and experienced at low speed, requiring a stop) shouldn’t be underestimated. We only really find out how we behave in unlikely/unforseen scenarios when they actually happen...

Landflap

12th Feb 2021, 08:37

Geeeps, some of you guys made my job easy. You know, the bit where, in the de-brief, I take my "Training hat" off, put on my "Examiner Hat" , place my portable licence shredding machine to 'warm up mode' and say..........." I think we'll stop you there "........

Crosswind Limits

12th Feb 2021, 09:30

Landflap,

You have added nothing thoughtful or meaningful to this discussion other than stating the bleeding obvious and when that fails, frustration fuelled sarcasm aimed at other posters. A cursory review of some of your past posts would lead me to conclude I would rather sit next to FullWings on a flight or have his ilk training or testing me in the sim.

I have absolutely no problem with this post being removed by the moderators.

Gordomac

13th Feb 2021, 08:51

Xwind: "Frustration fueled sarcasm" clearly displayed by yourself. Cursory view of your threads suggests similar explosions that Landflap, me and many others of our ilk look carefully at not only in the training/ testing but at the very basic selection procedure.

Choosing to sit next to our behind anyone on a flightdeck is is a choice you can enjoy. ( actually, do you have a choice in your company-?) But do exercise that choice carefully X-wind. I know who I would rather be sitting next to as we hurtle towards V1 . I also think that the hotheads who extol the virtue of "thinking outside the box" as they hurtle towards VR after V1 troll these forums in increasing numbers.

I think your post adds nothing thoughtful or meaningful to the "discussion" either and , once again, you might be moderated out. Surprised it is still up after 24 hrs.

ManaAdaSystem

13th Feb 2021, 11:29

I think XWind is spot on.
An instructor who refuse to see that in some cases a GO after V1 may be the only option, is not one I would like to have in the sim. Or the aircraft.
I’m happy with the V1 concept, I use it in the sim every time I’m there. We all do. It doesn’t mean we go outside the box every time we practise, but we refuse accept a «that can’t happen» attitude when we fly.

V1 is basically an engine failure speed, but over time other failures have been added. WS, Fire, etc. I do fly out of very limited runways in the winter time. A stop at V1 on a short, contaminated runway is very doubtful to be a success. An engine fire (listed as a stop both by Boeing and Airbus) with that engine still producing thrust, is a GO for me.
Landflap would stop and most likely end up in freezing seawater. Because that is what the book says. No exception. No thinking.

Gordomac

14th Feb 2021, 08:23

Manad; You admit to disagreeing with Boeing, Airbus, and most professional pilots. GO, after V1, with engine fire .(?) I. for one would rather be with Landflap in the freezing water Actually, I was. But that was in some Manch public pool doing our ditching drills..
Steering back to thread though, I do feel that the AIB was wrong. The Commander was wrong. The bent aeroplane at the end of KTM's runway proved it. Advocating "thinking outside" of the box after V1 , in the cases we are discussing, is very likely to have you being carried away in a pine box. Along with many, quite innocent people.

vilas

14th Feb 2021, 08:57

I really wonder what is the discussion about. You cannot deny that for any problem before 80 or 100kt (depending on whether B or A) you stop go back and have it checked, beyond 100kt carry on unless a few things happen. After V1 just get airborne even with fire and handle it in the air. If you are unable to get airborne at Vr what's there to discuss? You are forced to stay on Ground so try to stop and crash into something as slow as possible.

The Deec

14th Feb 2021, 09:33

I think this should be an autonomous decision, let the computers decide the best course of action after v1... I thought it was a simple go or no go decision, am I wrong ? This is a decision speed for a reason not to be messed with and certainly not a time for looking for quick fixes. It proves that you cannot leave the decision to trained professionals in this case, there's too much at stake. Practising this scenario in a sim is totally different to the real thing. You are relying on the human response on the day at that particular time to decide the fate of peoples lives.

PEI_3721

14th Feb 2021, 11:12

Learning from this thread:-
Hindsight bias is an insidious and powerful influence; some posters acting as though they are a video referee, forgetting that aviation does not allow replays.

ManaAdaSystem

14th Feb 2021, 13:01

Gordomac

GO after V1 in case of an engine fire is SOP, what are you talking about?
I say GO before/close to V1 if both engines give normal thrust, even with a fire warning. I'm pretty sure you have never departed for a snow/ice contaminated runway with max flap setting, max thrust and close to 0 stopping margin. I know that any given braking action is a best guess. I know that braking action is not the same all over the runway. I know that conditions can change very fast. I know that if I abort at V1, chances are I will go off the end and people will die.
On the other hand, I know that an engine fire is really an overheat. It may just be a bleed leak. I know that if I continue, I will be airborne well before the runway end. I have performance to shut it down in the air, and odds are the fire warning will go out. I then have a full runway for landing and stopping.
And before you say I should not depart when conditions are like this? This is what I do. This is part of my job for months every winter. I'm paid to use my brain, not to be a SOP monkey.

I had a simulator instructor once who told me the most importance thing to get done if you depart and the aircraft is filled with smoke, are the procedures. I asked if maybe getting the aircraft on the ground ASAP should be a priority? No, then you are not legally protected, was the answer.
So you and landflap prefer to flop around in the ice water with dead bodies floating around you, because thats what the book tells you to do.

Landflap

15th Feb 2021, 08:26

Oh dear. Troll Master Caution going on. As we are short of 80kts I will stop myself here ! . Quick debrief for our hot headed contributors ; Between 80kts & V1, in all professional outfits I worked for, the "Engine fire" situation was ;"as confirmed by two parameters ...........ManaAdaSystem tries to qualify an earlier statement and goes on to mitigate with a silly taunt about dead bodies in freezing water - very worrying but pretty much on profile. For the cooler heads, thank heavens, very clear support of what is a no-brainer. Damn, burnt me fingers on me Licence Shredder !

excrab

15th Feb 2021, 09:03

Land flap,
Out of interest, after the fire warning / bell what is the second parameter you would expect me to use to identify an engine fire to avoid you shredding my licence ? I ask because in the non normal manoeuvres section of the Boeing 737 800 QRH at the professional outfit I work for it says we should reject between 80kts and V1 for any fire or fire warning, and only requires two parameters for the engine failure case. If, as you suggest there should be two parameters to reject for a fire then the poster who says he or she would continue for a fire with no loss of thrust is correct according to your statement, the fire warning is the first parameter but if there is no loss of thrust, no yaw, nothing on the engine instruments then there is no second parameter.

Landflap

16th Feb 2021, 09:43

Exie ; Ours just says "Engine fire" as evidenced by at least two "parameters. It does not talk about the parameters that produce a " warning". Engine failure is a failure and would be clearly evidenced by other control factors that, surely don't need at "least two other parameters". or deep discussion. Up to V1, a "failure" would be pretty obvious. I would not seek a second confirmation to a boot full of rudder.

Drifting a long way off thread though. Someone earlier asked about some thread about calling V1 before V1. There was one. That too drifted a long way off into the hand-bag swinging this is getting close to. We do call V1 at V1 minus 5 kts & even stress the speed, in knots, that the call will be made at.

Kathmandu AIB publication is the thread and I must, finally agree with all the others that, quite simply, rejecting after V1 proved horribly wrong.

Stuka Child

17th Feb 2021, 14:42

Thread recap for those who might have missed the important points or are purposefully ignoring them:

- Boeing guidance has always been that rejecting post-V1 is not recommended (which for the obviously English-speaking people who are pretending not to understand English is not the same thing as forbidden), but it remains at the Captain's discretion if the Captain judges the aircraft unsafe to fly*. As for airlines, not sure what outfit you fly for, but I have never seen it phrased as anything other than you are encouraged to continue after V1, but this is by no means a command to go at any cost. That little phrase "unsafe to fly" is always, always there, in order to give you the freedom to adapt to whatever crappy circumstances you might be faced with one day.

- For this particular incident, the report agreed with the Cpt's decision to abort, even though said decision was wrong in hindsight. Why did the investigators then give him the benefit of the doubt? Because he judged the aircraft unsafe to fly. Every Captain must make this decision on every takeoff, and unfortunately there is no clear guidance on what would help her or him decide what makes an aircraft unsafe to fly. This is where judgement is exercised*.

- A study examining high speed aborts found that 31.9% of decisions to reject after V1 were correct, 44.4% were incorrect and the rest debatable. That is to say, in 31.9% of these cases, continuing after V1 would have resulted in a crash. It is not the majority, but it is a lot, and it puts to sleep your theory that there is never a reason to stop after V1. I don't see how it's thinking outside the box or being hot-headed to save passengers' lives.

* unsafe to fly and exercising judgement: if you are making the argument that you would never reject above V1, your judgement is not sound and you are not fit for a captaincy. Popped tyre? Sure, go! Engine failure with remaining engine generating adequate thrust? Let's get it! Engine fire? Not your best day, but ok, go!
However, any major fire, anything next to flight control surfaces, wing fire, fire near the tail, cockpit fire, cockpit rapidly filling with smoke - you cannot possibly contemplate going up. You might not even have time to make a VFR turn back to the runway, let alone shoot an actual approach. There might be terrain, you might fly into IMC, you might be taking off at night...just take the overrun. Much better to drive into something at 100-something knots than to fly into something or drop out of the sky.

For a runway like Centaurus' or like the Aussie poster's a little earlier in the thread, where you have a massive seawall at the end and the sea beyond - let's say you have one of those catastrophic fire scenarios. What do you do? You again exercise your judgement and make the best of your circumstances. You rotate, clear the boulders or concrete and come right back down onto the water. Many people have survived overruns (and underruns) into the water, as it is among the mildest accidents you can have, many people have survived ditching, but if you lose control and nosedive into the ocean, the list of survivors becomes much thinner. I can't believe I have to say this, but don't take up a burning aircraft!

Whoever has trained you, nothing in your training precludes common sense. You must always be aware of what your best chances for survival are, and take them when you have to.

safetypee

17th Feb 2021, 17:59

Stuka, interesting views;
‘… rejecting post-V1 is not recommended … is not the same thing as forbidden …’, yet there are operators with very good language skills which simplify their safety responsibilities by declaring any manufactures recommendation as mandatory.
Some checklists have ‘except’; ‘ freedom to adapt ‘. However, any decision in this category depends on knowledge, the quality of judgement, awareness, and risk assessment in time-restricted surprising circumstances. All individual human attributes, not something which can be predetermined nor something which can be identified after the event.

For every exception (one persons judgement) there is an alternative (another person); arguing fire severity and location are unknowable in real time during takeoff. These are situations which defy logical argument before the event, but which reflect misjudgement in real situations, more often based on assumption *.

Before considering such extreme ‘what if’s compare their likelihood against certification requirements.
These are based on ALARP; not every possibility, but those situations which are Reasonable and Practical (which contribute to the current good level of safety). The requirements consider combined fire / control system (fire containment, distancing from controls, dual control paths); we should not challenge what design and certification has already considered.

* In the HF section of the PSM+ICR report, the analysis refers to the Boeing Engine Malfunction database. This listed 21 events of discontinuing takeoff after V1; none involved inability to fly (and few actual engine related), but all involved judgement and assumption.