Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Final Report: April 2018 737 high speed aborted TO

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Final Report: April 2018 737 high speed aborted TO

Old 13th Feb 2021, 12:29
  #121 (permalink)  
Join Date: Aug 2000
Posts: 1,492
Likes: 0
Received 0 Likes on 0 Posts
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.
ManaAdaSystem is offline  
Old 14th Feb 2021, 09:23
  #122 (permalink)  
Join Date: Mar 2011
Location: Cyprus
Posts: 350
Likes: 0
Received 0 Likes on 0 Posts
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.
Gordomac is offline  
Old 14th Feb 2021, 09:57
  #123 (permalink)  
Join Date: Jun 2007
Location: Wanderlust
Posts: 3,205
Likes: 0
Received 0 Likes on 0 Posts
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.
vilas is offline  
Old 14th Feb 2021, 10:33
  #124 (permalink)  
Join Date: Jan 2009
Location: groom lake
Posts: 55
Likes: 0
Received 0 Likes on 0 Posts
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.
The Deec is offline  
Old 14th Feb 2021, 12:12
  #125 (permalink)  
Join Date: Mar 2006
Location: England
Posts: 958
Likes: 0
Received 0 Likes on 0 Posts
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.
PEI_3721 is offline  
Old 14th Feb 2021, 14:01
  #126 (permalink)  
Join Date: Aug 2000
Posts: 1,492
Likes: 0
Received 0 Likes on 0 Posts

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.
ManaAdaSystem is offline  
Old 15th Feb 2021, 09:26
  #127 (permalink)  
Join Date: Aug 2007
Location: UK
Posts: 0
Likes: 0
Received 0 Likes on 0 Posts
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 !
Landflap is offline  
Old 15th Feb 2021, 10:03
  #128 (permalink)  
Join Date: Jun 2001
Location: The middle
Posts: 532
Likes: 0
Received 0 Likes on 0 Posts
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.

Last edited by excrab; 15th Feb 2021 at 10:17.
excrab is offline  
Old 16th Feb 2021, 10:43
  #129 (permalink)  
Join Date: Aug 2007
Location: UK
Posts: 0
Likes: 0
Received 0 Likes on 0 Posts
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.

Landflap is offline  
Old 17th Feb 2021, 15:42
  #130 (permalink)  
Join Date: Apr 2019
Location: Montreal
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
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.
Stuka Child is offline  
Old 17th Feb 2021, 18:59
  #131 (permalink)  
Join Date: Dec 2002
Location: UK
Posts: 2,311
Likes: 0
Received 0 Likes on 0 Posts
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.
safetypee is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.