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Emirates B777 gear collapse @ DXB?

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Emirates B777 gear collapse @ DXB?

Old 14th Sep 2016, 12:51
  #1521 (permalink)  
 
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The RAAS technical description in Tech Log raises further questions and provides a interesting scenario which might relate to this accident.

The RAAS 'Long Landing" alert is only given in the air between 100ft and 5ft RA.
The distance down the runway where the alert is given is pre-selectable by the operator according to aircraft type and runways used.
The position information comes from GPS (GPS/FMS or internal GPS in EGPWS? Which is more accurate?). The warning distance appears to be based on GPS, but could involve ground speed-distance calculation from either the threshold or runway end.
The 'standard' distance is 2000ft or 25% of the runway. 2000ft might be a bit short for a 777, particularly when regularly operating in tailwinds: 2000ft is 25% of an 8000ft runway, thus some compromise is required. The distance chosen by this operator is not known, nor the option of fixed distance or %.

The 'only in the air' aspect is very interesting.
Requiring a go-around after an alert would, with simple assumption, always be an 'airborne' GA where TOGA will provide auto thrust commands, even if the aircraft subsequently touches the runway as the AT will remain engaged.
However, if the alert is very close to the ground, above 5ft, it would be possible - likely, that the TOGA selection could be made below 2ft, where the auto thrust (TOGA) is inhibited.
More frequent alerts might be expected in this situation because the aircraft is always reducing the distance to the long landing point during a normal landing.

In such a scenario a crew can follow the procedures, expect normal auto thrust operation based on the (incomplete) Boeing/FCOM system description - "TOGA is inhibited on ground". The crews expectation may be enhanced by normal operations (always use AT).
Although the manual thrust arguments are well founded, it is probable that a 777 PF never manually advances the thrust levers - not during takeoff, and nor during a GA (do operators encourage two handed finesse for pitch control to avoid a tail strike?).

During takeoff the crew focus is on power and speed, the task is to fly.
During a GA the task has to be quickly reformulated from the landing objective; PF has to fly, PM select flaps, check FMS, FMA, and hearing, noting, and responding to ATC clearance ... and verifying that the thrust is set.
A 10-12 sec delay in identifying the unexpected AT operation might be reasonable given the workload and behavioual influences.
And as much as the manufacturer, regulator, management, (or some Ppruners) might expect the crew to recall the FCOM notes on page 4.29.17. line 12, or the textural rejected landing procedure, humans, pilot's do not function that way, particularly in very rare and surprising situations, where procedures have been actioned correctly, ... with a minor oversight which subsequently appears to have been identified, but a little too late.

This is an 'as designed' situation, with opportunity for misleading system operation, and probably with the gross assumption that the crew will manage error avoidance, detection, and mitigation: in a time scale much shorter than it takes to read this post.
Pilots have a responsibility for safety, but just because they are the last line of defence, their responsibility does not include the responsibilities of those who have much more time and influence to consider the situation; the regulators, manufacturers, and operator.
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Old 14th Sep 2016, 14:34
  #1522 (permalink)  
 
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BuzzBox
When one flies automated FBW aircrafts isn't it necessary to know the limitations of automation? I think if the pilot knew that throttles will not advance by triggering the GA button then he would have pushed it manually. Inadequate knowledge of auto throttle/FD in GA mode is the cause of this accident. It's not that pilots don't read but may fail to see the trap system can get them into. Airline's OPs/TRG department needs to disseminate such information. I am sure it will be done now. If only AF447 pilots knew that you never yank the stick back in alternate law they may have survived because that's what set the ball rolling. We talk of lack of basic flying skills but now in addition insufficient knowledge automation is also getting added to that.
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Old 14th Sep 2016, 16:00
  #1523 (permalink)  
 
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vilas, the complexity of modern aircraft is such that it is unrealistic to expect pilots to understand, remember, and recall all of the details, even just those deemed important. And who chooses what is relevant anyway.
Even if all pilots were to be aware of a system's limitations, it would not alter the risk of encountering an adverse situation. It is difficult, if not impossible to allocate a meaningful probability to human reliability; there are too many variables and unknowns.
One very influential safety action is to change the conditions of work so that the 'system', technical design, documentation, and procedures will help the pilot in these rare conditions.
Certification was discussed earlier in the thread. We assume that the initial certification of the 777 AT operation was judged acceptable - frequency of occurrence and consequences - in context.
Since then there may be greater exposure due to the additional focus on a bounced landing; the risk increased, but probably not re-evaluated.
The introduction of RAAS appears to further increase the exposure; furthermore assuming that the TOGA AT RAAS were to be contributory in this accident, then the outcome aspects of inappropriate TOGA selection could be re-considered.
Then what would be changed, man, machine, or environment; which would be more effective.
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Old 14th Sep 2016, 16:16
  #1524 (permalink)  
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I have patiently waited to see an explanation of something that has been puzzling me, but don't think one has emerged - and I don't think it is going to unless I ask.

One focus of attention has been the TOGA button, which I understand commands the autothrottle to provide "take off" power - so lots of thrust.

We have learned the TOGA feature is inhibited when the plane is on the ground - more accurately the weight on wheels sensors are detecting that the plane is ground - again subject to some "cleverness" taking account of the multiple sets of wheels.

I understand TOGA to mean "Take Off / Go Around".

When a plane takes off "normally" it starts, by definition, on the ground. There will be weight on wheels, so TOGA should, it would seem, be inhibited?? Clearly a nonsense - I must be misunderstanding something.

So why is TOGA not inhibited for a "normal" takeoff - or what is it the PF does to override the inhibition? Or does the operation of the button change from TO to GA such that in TO mode the WOW is not relevant, only in GA? If the function changes, what tells the TOGA function that this is not a take off, but is a go around - or vice versa?

Please don't flame me - I have been patient! I am not a pilot - well, I flew a glider solo three times four and a half decades ago, but I do not think that gives me much credibility. And I have been well battered SLF for many years. But I am an engineer, and because of some studying I did into the use of expert systems / artificiall intelligence in automation some years ago am VERY curious about this incident as it raises fascinating questions about the dividing line between man and machine holding authority over operating the system.

In another question - surely the thing the RAAS system should be "concerned" about is how much usable runway is ahead - not how much lies behind the plane - but again I may be miusnderstanding.
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Old 14th Sep 2016, 18:20
  #1525 (permalink)  
 
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When a plane takes off "normally" it starts, by definition, on the ground. There will be weight on wheels, so TOGA should, it would seem, be inhibited?? Clearly a nonsense - I must be misunderstanding something. So why is TOGA not inhibited for a "normal" takeoff - or what is it the PF does to override the inhibition? Or does the operation of the button change from TO to GA such that in TO mode the WOW is not relevant, only in GA? If the function changes, what tells the TOGA function that this is not a take off, but is a go around - or vice versa?
The autoothrottle is part of the auto pilot system. The autopilot has multiple modes such as takeoff, cruise, and approach. When in takeoff mode the TOGA switch activates the Take Off function. When in Approach mode the TOGA switch activates the Go Around function. When in Approach mode weight on wheels (or a very low radar altitude) will inhibit TOGA.

In another question - surely the thing the RAAS system should be "concerned" about is how much usable runway is ahead - not how much lies behind the plane - but again I may be miusnderstanding.
That depends on how the RAAS system is set up. For example on a dry runway, 4000 ft remaining may be plenty to stop the aircraft. But that may be insufficient for a wet or snowy runway. So the RAAS may be set up to give an alert whenever a certain amount of runway has been used to account for "a worst case scenario" that RAAS cannot detect. Normally the flight crew would know what the braking action is on a runway and take appropriate action when RAAS provides an alert. On a dry runway the appropriate action would probably be to land the aircraft. If there is poor braking action, the appropriate action may be to do a Go Around. In this case the airline's operating manual apparently required the flight crew to do a Go Around with any RAAS alert. That sounds prudent on paper, but under the right set of circumstances it may be imprudent. In this case the circumstances all lined up to result in an unnecessary disaster. RAAS also provides alerts during ground taxi to alert the pilot they are about to cross a runway. If the pilots have received clearance to cross the runway, the pilots ignore the alert and proceed, but if not, they should stop. It also provides an alert in the event they line up for takeoff on a taxiway instead of a runway.
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Old 14th Sep 2016, 18:57
  #1526 (permalink)  
 
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M.Mouse
Clearly you do not fly either the B777 or B777.
You are right, I neither fly the B777 nor the B777 However, my point is type-independant.

M.Mouse
... and the autothrottle system handles the power extremely well and, in gusty conditons especially, arguably far better than the PF could hope to do.
Except once in AMS. And except once in SFO. And except once in DXB. We don't need speed control on the knot, what we need is never speed dropping 20kt below bug unnoticed for 20 sec, or never going around with just pushing inhibited buttons.

Didn't the crew of the lost BA A319 cowling in LHR have problems flying without ATHR since they never did it before outside of the simulator? I certainly didn't want to have my first ATHR off approach under the stress of an abnormal.

alf5071h
During takeoff the crew focus is on power and speed, the task is to fly.
During a GA the task has to be quickly reformulated from the landing objective; PF has to fly, PM select flaps, check FMS, FMA, and hearing, noting, and responding to ATC clearance ... and verifying that the thrust is set.
A 10-12 sec delay in identifying the unexpected AT operation might be reasonable given the workload and behavioual influences.
And as much as the manufacturer, regulator, management, (or some Ppruners) might expect the crew to recall the FCOM notes on page 4.29.17. line 12, or the textural rejected landing procedure, humans, pilot's do not function that way, particularly in very rare and surprising situations, where procedures have been actioned correctly, ... with a minor oversight which subsequently appears to have been identified, but a little too late.
I strongly agree. In certain dynamic situations it is impossible to absorb all the indications from the FMA fast enough, it just doesn't work. That is why we need more hands on work. KISS, keep it simple stupid.

Manual flight equals manual thrust would have prevented this accident. As it would have many more. Pilots need to be in the loop, speed scanning MUST become second nature again, for all crews, not just for most.

alf5071h
This is an 'as designed' situation, with opportunity for misleading system operation, and probably with the gross assumption that the crew will manage error avoidance, detection, and mitigation: in a time scale much shorter than it takes to read this post.
Pilots have a responsibility for safety, but just because they are the last line of defence, their responsibility does not include the responsibilities of those who have much more time and influence to consider the situation; the regulators, manufacturers, and operator.
Strongly agree. It would not have happened if AFS-mode-selection was designed into the thrust levers itself as it is with Airbus.

Didn't AF in CDG have an incident with the B777 TL-button design? Instead of TOGA buttons they pressed ATHR disconnect buttons and advanced the TL manually, so the plane kept following the glide while accelerating close to the ground. AFS-mode-selection within the TL-itself would just be much more intuitiv.

Last edited by 1201alarm; 14th Sep 2016 at 19:13.
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Old 14th Sep 2016, 19:09
  #1527 (permalink)  
 
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Auto-thrust. I've seen it on B757/767/737NG be very lethargic. Equally I've seen many an F/O be over enthusiastic. Thrust management on finals is a fine art. It's not wait for limits then handfuls on or off. I've watched manual thrust actions where there was no appreciation of what the airology was doing. Changes from tail to headwind with huge thrust changes. Flying through thermals with high thrust changes. Usually it was large reductions of thrust only to find that a few seconds later it was needed to be increased. It would have been better to leave the datum and let the speed oscillate a little with delicate adjustments.
This was educated via non-autothrust a/c and an understanding of the environment. The auto-thrust has no such knowledge. It is a limit system. The pilot who flys with A/T also has no education of the environment.
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Old 14th Sep 2016, 20:42
  #1528 (permalink)  
 
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Auto Thrust
Auto Pilots
Auto Mation

None of it is designed nor programmed by Pilots. That's why you HAVE to be suspicious of it.

I believe Humankind's greatest achievement was going to the moon AND coming back. And it's very telling... The Astronauts, Drivers, Chiefs, Bwanas, whatever you demand they should be called, insisted that the voice they heard on the radio, was one of them, not a scientist, not a manager, not a systems designer. Another person that did exactly the same as they did.

There was inherent trust in the operation because there were checks and balances in the system that removed ego and intransigence.

Our profession hasn't been so fortunate. This profession has degenerated to the point where the wrong people have authority, not because they deserve it, but because they can quote chapter and verse.

There have been posts on this thread that really want to find the Captain at fault because... he is a local! Well thinking outside of the box just might allow this investigation to develop more, into looking into the extenuating circumstances of this accident.

Yep, bigots might say it's to protect the local, but if the investigation delves into the training culture and finds an issue with it, pilots all over the world will be glad there was an indigenous commander at the controls, because his country will stand behind him. And it's a very good thing because the investigation won't be so bigoted and will look beyond him, unlike the Uk and Captain Stewart who landed his 747 without much fuel...And I hope they castigate the training regimes they have inherited. The training culture, clearly leaves a lot to be desired.

2, 7,000+ hour pilots, that flew a G/A without increasing thrust... Neither of them... That has nothing to do with nationality, that points to the fact they have been in the wrong training environment, professionally, for a very long time.

The cause of this accident is to do with a lot more than Auto anything.

Last edited by 604driver; 15th Sep 2016 at 10:24.
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Old 14th Sep 2016, 20:45
  #1529 (permalink)  
 
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Originally posted by vilas
When one flies automated FBW aircrafts isn't it necessary to know the limitations of automation?
Yes, of course it is, and therein lies one of the problems. In the past, these hidden 'traps' of the 777 autoflight system (eg FLCH HOLD mode, TOGA inhibit, etc) have been poorly documented and poorly trained. We've seen at least three serious incidents/accidents over the last few years (SQ at Munich, Asiana at SFO and now EK at DXB) where the pilots' poor understanding of these traps seems to have been a factor. It's high time the manufacturer and the airlines recognised the problem, provided better documentation and procedures, and trained people accordingly.
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Old 14th Sep 2016, 21:14
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Sadly, it is clear that the most qualified Pilots are those who have flown Jets that still require a scan and manipulation of the thrust levers, those Pilots are often the ones who are disregarded. Modern accidents appear to be associated with reliance on automation and SOP's (which are very important but the use of common sense is more important).
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Old 14th Sep 2016, 21:15
  #1531 (permalink)  
 
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notapilot, #1573, I don't disagree with action before reporting, but I would question the assumption that most airlines learn from their own and others mistakes.
Have all of the mistakes been identified, is 'error' reporting as widespread as the Just Culture promoters imagine. Which operators share safety data, real data; there are some good examples, UKFSC, but what about the outsiders.
Is the reasoning behind 'the error' fully understood, e.g. It appears that many pilots in this thread have or have known someone who has learnt about the 777 TOGA AT GA functioning through experience (error), but how many of these events were reported, who else knew, and what action was taken.
Mandatory reporting is fine providing the report is a true reflection of the incident and contributing factors. Unfortunately pilots, humans, more often 'blame' themselves and do not question the technical system or wider influences affecting behaviour.
Also, who publicly reports incidents which do not fall into the mandatory categorisation.
A sceptical view maybe, but an optimistic sceptic.
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Old 15th Sep 2016, 03:06
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1- If not from the LONG LANDING audio message it is most probable the guys would have simply completed their landing, but didn't like the idea to have to meet the boss for disregarding the computer ...
2- What made the PF think he could rotate without feeling the thrust output first ?
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Old 15th Sep 2016, 06:52
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What made the PF think he could rotate without feeling the thrust output first ?
7000+ hrs of longhaul, widebody flying, staring out the window trying to keep his eyes open while the automatics kept him safe?

We've seen at least three serious incidents/accidents over the last few years (SQ at Munich, Asiana at SFO and now EK at DXB) where the pilots' poor understanding of these traps seems to have been a factor
They all forgot to fly the aircraft.
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Old 15th Sep 2016, 07:14
  #1534 (permalink)  
 
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They all forgot to fly the aircraft.
I said a poor understanding of the traps was A factor, not the ONLY factor.

Last edited by BuzzBox; 15th Sep 2016 at 07:36.
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Old 15th Sep 2016, 07:18
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Sure, but there is a simple way out of the situation.

Am I a pilot or a passenger? What every pilot should ask him/herself before going to work.
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Old 15th Sep 2016, 07:37
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Problem solved then. No need to look any further.
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Old 15th Sep 2016, 08:04
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It's all very well saying we should know the FCOM inside out ( true) but it's one thing being able to recite the books, it's another one understanding every subtle nuiance and logic trap that the designers may have buried in the system- and there are more than a few. Over the years on a couple of the big Boeings I've certainly seen manuals and company training " morph" as yet another aspect of the autothrottle system has been discovered by some poor so and so on the line....(and I'll fess up and say been there and explored the system logic, or apparent lack of it on a GA from a lowish platform altitude one dark and not so stormy night....)

However ultimately yes, you have to be prepared to get rid of the automatics.
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Old 15th Sep 2016, 08:30
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No one can remember everything in all the manuals. There will always be circumstances where you will forget something or not be able to bring it to mind quickly enough in the time available. The less you use something, the more this will be true.


I once had an F/O bounce a badly executed x-wind landing some 50' into the air, with the thrust levers at idle, & then let go of the controls. I didn't even think of TOGA. I didn't have the luxury of the time required to think & then act. I simply pushed the thrust levers way forward & then tried to pick a pitch attitude that would not lead to a stall on one hand, but also not lead to an excessive sink rate on the other. Eventually the power came in & the incident had a happy ending, but it was not much fun.


Sometimes you just need to be able to fly, not operate the equipment.
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Old 15th Sep 2016, 08:44
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OMG Oakape, you didn't verify the FMA????
Very unsafe pilot, you are.

Well done!
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Old 15th Sep 2016, 08:49
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Originally Posted by ManaAdaSystem
They all forgot to fly the aircraft.
In this case I see that there were a few factors restricting their flying decisions...

1: Windshear: headwind turned to a tail wind so they landed long.
2: Long Landing not pilot fault but an OK Landing performed
3: automatics: LongLanding annunciated
4: Not your decision. See #5
5: Company SOP: You shall go-around buddy
6: Boeing: sorry but with WOW, Toga inhibited
7: EK SOP: Flaps 2, raise UC on +ve climb
8: OK, we did what we were ALLOWED and told
9: Whoops: +ve Climb was temporary
10: Alert: IAS falling, now lets start flying this brick
11: too late, no time to spool up.
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