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Final Report: April 2018 737 high speed aborted TO

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Final Report: April 2018 737 high speed aborted TO

Old 26th Jan 2021, 03:04
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Final Report: April 2018 737 high speed aborted TO

5811.pdf (skybrary.aero)
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Old 26th Jan 2021, 04:13
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And he was an IP !
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Old 26th Jan 2021, 04:53
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Strange. Maybe I missed it but as I read it, there was no record on the FDR of T/O Config Warning.

However the crew stated that the T/O Warning came on at around V1. The PIC then wasted a couple of valuable seconds dicking around with the speed brake handle to ensure it was in the detent and to no avail before initiating an RTO. Some people refuse to believe the numbers and think they know better, I guess.
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Old 26th Jan 2021, 05:54
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Page one: the purpose of the report is not to apportion blame!!
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Old 26th Jan 2021, 06:02
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The decision of rejecting the take-off was well taken since it was unsafe to continue considering the airport surrounding high terrain and bad weather conditions.
Well, the Malaysian AAIB seems to think the decision was well taken. I don't know Boeing's blurb but Airbus states that an RTO may still be initiated above V1 if there is a very strong indication that the aircraft is unsafe to fly. If there was any chance the performance was drastically reduced out of KTM I'd say that was a fair stop! Yes, 'dicking around with the speed brake handle' wasted a quite a few stopping yards and full stopping potential was not apparently realised; but there is a thing called 'startle' and it happened at a local time that, for me at least, is a low performance hour.
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Old 26th Jan 2021, 08:41
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Originally Posted by lucille View Post
Strange. Maybe I missed it but as I read it, there was no record on the FDR of T/O Config Warning.
No FDR data (CB not pulled) only QAR data. Boeing says:
"... the take of parameter present in the QAR data would not have been triggered. The S651 switch (Speed brake handle stowed switch, BDA) signal is provided to the proximity sensor electronics unit (PSEU) which then provides outputs for the takeoff config lights and aural warning module. The takeoff config warning parameter recorded by the QAR is sourced from the flap-slat electronics unit (FSEU)."
So the data was recorded somewhere in the middle of the signal path before aditional trigger conditions (speed brake not stowed) were OR'ed to it.
They do not say if the Takeoff config warning would have been captured differently for the FDR .

This perpetuates my views I expressed in the most recent MAX thread. E/E wise this plane was mess well before the MAX.
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Old 26th Jan 2021, 09:37
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He aborted because of a take off config warning, not a engine failure. Both engines running, so performance was not an issue. Poor excuse.
Not a good warning to get near V1, and he decided to abort. Fair enough, that was the commanders decision.
He failed in the execution of the aborted TO when he started to trouble shoot the warning. Poor decision.
A properly executed abort would have saved the day and we would not have this discussion.

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Old 26th Jan 2021, 10:21
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Report states decision to stop was made at 154 Kts. Well after V1 then. Between V1 & 154 kts, looks like the pilots were attempting to correct an indication of a fault. Not good but AIB reckons it was a good decision.

Been in & out of this demanding airfield many times in 767's. Doesn't matter what type or where though, ingrained is the notion that up to V1 you can stop, after V1 you go. No messing.

This case shows it was a false warning and if the crew had of continued, fly the aircraft, get safe and then mess about with analysis later, a better outcome would have resulted.
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Old 26th Jan 2021, 10:41
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The report is slightly misleading. My interpretation is that the captain thought that the decision to reject was a good one. Well in the words of Mandy Rice Davies he would say that wouldn’t he? Regardless of his IP status the decision to reject post V1 was not optimum and not a role model performance for Jet transport pilots. I have flown in / out KTM many times and the weather reports were not particularly threatening. The nasty thunderstorms normally occur in the afternoon. As a pilot it is better to take ownership of mistakes. An RTO above V1 is never likely to end well. The Boeing FCTM gives excellent guidance on this. The points ref startle and circadian low are well made. The loop closes on knowing sops and procedures to countenance the threats. Fortunately the outcome was not worse.
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Old 26th Jan 2021, 10:49
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Re the thread title.....

.....there but the grace of God etc......
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Old 26th Jan 2021, 11:22
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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.

Last edited by Uplinker; 26th Jan 2021 at 11:34.
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Old 26th Jan 2021, 12:45
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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.


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Old 26th Jan 2021, 13:34
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I'm not a 737 jock, so maybe a silly question but no mention of reverse thrust; would that usually be deployed?
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Old 26th Jan 2021, 14:22
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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.
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Old 26th Jan 2021, 14:30
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Malindo. Big brother or kissing cousin to Lion Air.
Take a look at some of the other threads if you want a few clues.
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Old 26th Jan 2021, 14:54
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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:

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Old 26th Jan 2021, 15:29
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"It's not things that upset us, but our judgments about things"

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 …
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Old 26th Jan 2021, 16:09
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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.


Last edited by ATC Watcher; 26th Jan 2021 at 21:57. Reason: title changed for the better
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Old 26th Jan 2021, 16:55
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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.

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Old 26th Jan 2021, 17:43
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Originally Posted by B2N2 View Post
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.
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