EK407 Tailstrike @ ML
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Do the commercial departments weigh up the cost of the risk that reduced thrust take-offs represent, versus the money they save? Everyone assumes they do, but do they?
Clearly, if you are going to severely damage (or worse) an airframe every year or two by planning EVERY take-off to involve rotating at the end of the available runway (and you cannot {as proven} have zero error in such ops= an accepted level of risk/loss), there has to be an enormous benefit in engine life/maintenance to offset.
As PIC and accepting the risk, shouldn't you be privvy to those numbers?
Clearly, if you are going to severely damage (or worse) an airframe every year or two by planning EVERY take-off to involve rotating at the end of the available runway (and you cannot {as proven} have zero error in such ops= an accepted level of risk/loss), there has to be an enormous benefit in engine life/maintenance to offset.
As PIC and accepting the risk, shouldn't you be privvy to those numbers?
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GMDS , your sentiments on accountability are so right. Its sickens me how the other " professions " are never held to account for their bad day at the office. Sorry dont mean to create a thread creep. But I have more respect for every single one of my colleagues ( brown nosing incapable office types excluded), but not a single member of those " professions" .
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As prop jet says, Airbus makes use of the full length of every runway in their performance and reduce the thrust as much as possible to a minimum allowed value. You're most welcome to use more thrust, or TOGA, which would shorten the take-off length. Most airlines promote the Flex take-off for engine life/cost.
Thrust may not be flexed below 25% (A340-300) 40% (A340-500) ref FCOM 2.02.01 pg 14, of the entire thrust and all climb gradient segments must be made.
This is to say, that on a wide body in general, medium to long flight, you will always be having the opportunity to visit the far end of most runway rather closely when rotating.
Screwing up the figures or weights, will always have a disastrous effect.
Thrust may not be flexed below 25% (A340-300) 40% (A340-500) ref FCOM 2.02.01 pg 14, of the entire thrust and all climb gradient segments must be made.
This is to say, that on a wide body in general, medium to long flight, you will always be having the opportunity to visit the far end of most runway rather closely when rotating.
Screwing up the figures or weights, will always have a disastrous effect.
Last edited by Jetjock330; 1st Apr 2009 at 15:32.
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Errors
Reading the postings, it seems that people think that the risk only lies in reducing thrust - not so!
Even if you would use full thrust on every take-off, if you have determined the associated speeds with the Zero Fuel Mass, instead of with the Take Off Mass, you will probably scrape the tail on rotation. Granted, it will happen not so near the departure end of the runway, but still the airplane will be damaged.
As for self weighing aircraft: they do exist! Many cargo aircraft have such a system. Not terribly accurate, but it should provide protection mainly against gross Centre of Gravity errors. However, if such a system is u/s, aircraft dispatch will be allowed according MEL - and then, safety is provided, as on any other aircraft, by rigorous procedures.
Even if you would use full thrust on every take-off, if you have determined the associated speeds with the Zero Fuel Mass, instead of with the Take Off Mass, you will probably scrape the tail on rotation. Granted, it will happen not so near the departure end of the runway, but still the airplane will be damaged.
As for self weighing aircraft: they do exist! Many cargo aircraft have such a system. Not terribly accurate, but it should provide protection mainly against gross Centre of Gravity errors. However, if such a system is u/s, aircraft dispatch will be allowed according MEL - and then, safety is provided, as on any other aircraft, by rigorous procedures.
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Resign = Admit responsibility for the error and take your saved company scheme cash.
Sacked = Don't admit full responsibility for the error (other factors also at play) and company won't let you take the cash = BLACK MAIL!
So....Your liablilty (they win when you resign as not their fault). Part company liability possibly (they won't pay out your cash and they win when they fire you).
Sacked = Don't admit full responsibility for the error (other factors also at play) and company won't let you take the cash = BLACK MAIL!
So....Your liablilty (they win when you resign as not their fault). Part company liability possibly (they won't pay out your cash and they win when they fire you).
In a very dynamic situation at speeds in the order of 160 KIAS, it's simply not possible to look outside and accurately determine whether planned acceleration is matched by actual.
As prop jet says, Airbus makes use of the full length of every runway in their performance and reduce the thrust as much as possible to a minimum allowed value.
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from Air Transport Intelligence - Pilots resign
Pilots resign after Emirates A340-500 accident
Kieran Daly, London (01Apr09, 13:11 GMT, 155 words)
The pilots flying the Emirates Airbus A340-500 that suffered a severe tailstrike at Melbourne on 20 March have left the airline.
A spokesman for the carrier says: "I can confirm that they have resigned." He declined to give any further explanation.
The aircraft (A6-ERG) remains in Australia after being extensively damaged on take-off from the 3660m (12,000ft) runway 16 during which it suffered at least one tailstrike and is reported to have struck antennas just beyond the runway end.
It climbed to an intermediate altitude before dumping fuel for about 30min and then returned to Melbourne instead of continuing to Dubai. It landed without further incident.
No further information on the cause of the accident has been released, although ATI understands that suggestions of a problem with one of the four Rolls-Royce Trent 500 engines have been ruled out, despite passenger reports of seeing sparks or flame from one of them during the take-off run.
Source: Air Transport Intelligence news
Kieran Daly, London (01Apr09, 13:11 GMT, 155 words)
The pilots flying the Emirates Airbus A340-500 that suffered a severe tailstrike at Melbourne on 20 March have left the airline.
A spokesman for the carrier says: "I can confirm that they have resigned." He declined to give any further explanation.
The aircraft (A6-ERG) remains in Australia after being extensively damaged on take-off from the 3660m (12,000ft) runway 16 during which it suffered at least one tailstrike and is reported to have struck antennas just beyond the runway end.
It climbed to an intermediate altitude before dumping fuel for about 30min and then returned to Melbourne instead of continuing to Dubai. It landed without further incident.
No further information on the cause of the accident has been released, although ATI understands that suggestions of a problem with one of the four Rolls-Royce Trent 500 engines have been ruled out, despite passenger reports of seeing sparks or flame from one of them during the take-off run.
Source: Air Transport Intelligence news
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From early days, we have seen the concept of lets blame the pilot, particularly if they cannot answer for themselves. In some cases the situation just like this one, can be part pilot error, but often there are other facts that come into play, and if it suits the operator they can be smoothed over.
Does appear that in this case the pilots made a severe error of judgement, but then the system of checks should have caught the situation, long before it became life threatening. In this case the operators of the aircraft, are sitting back in their offices confident that they have had justice done. However they are failing to understand that wall papering over the cracks does not fix the problem.
I am sure that on this forum, there are many who are thinking "there but for the grace of God go I". It will interesting to see what change of operating procedures Airbus will bring out to avoid this and other situations coming back to haunt.
As for the pilots, would have thought this incident would have made them better pilots and should not be a reason to put them on scrap heap. Certainly showed considerable skill in their handling of events after the scrape.
As an after thought, I wonder if the rest of the fleets bulkheads have been checked, if the story put around of regular over loading has merit, perhaps some of the damage was already there and was only compounded by the incident.
Regards
Col
Does appear that in this case the pilots made a severe error of judgement, but then the system of checks should have caught the situation, long before it became life threatening. In this case the operators of the aircraft, are sitting back in their offices confident that they have had justice done. However they are failing to understand that wall papering over the cracks does not fix the problem.
I am sure that on this forum, there are many who are thinking "there but for the grace of God go I". It will interesting to see what change of operating procedures Airbus will bring out to avoid this and other situations coming back to haunt.
As for the pilots, would have thought this incident would have made them better pilots and should not be a reason to put them on scrap heap. Certainly showed considerable skill in their handling of events after the scrape.
As an after thought, I wonder if the rest of the fleets bulkheads have been checked, if the story put around of regular over loading has merit, perhaps some of the damage was already there and was only compounded by the incident.
Regards
Col
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QA standards at least in Australia, is focused on procedures and paper flow. It has nothing to do with quality of product at the end. It has nothing to do with even if proper process takes place, what it means is the flow of events is docuemented and is followed.
One could be producing the same crap product day in and day out but you could still meet the needs of the QA policy.
So the paperwork could be perfect, but the actual product like in this case could be flawed.
Regards
Col
One could be producing the same crap product day in and day out but you could still meet the needs of the QA policy.
So the paperwork could be perfect, but the actual product like in this case could be flawed.
Regards
Col
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Ed,
The issue here may well have had no different result if the wrong speeds were used. ie the acceleration to (your speed) of 100 KIAS would probably have been within a few seconds of normal.
The problem could have been trying to rotate the aircraft at much too slow a Vr. The aircraft just wasn't ready to fly. They would also have been above the "wrong" V1, and we are all trained to go after that speed.
As has been said before, it is an extremely dynamic situation and valuable seconds would have been taken in wondering why the aircraft wasn't responding. The rotation process over say 5 seconds would have consumed well over 1000 ft in itself, and probably much more with the drag of a continuous tail strike.
The hindsight committee will no doubt say they should have lowered the nose to the correct pitch attitude and immediately apply TOGA thrust. The crew on the night was faced with a situation that they had never ever seen before - so comment after the fact is of little consolation to them.
Time assessment on very heavy take offs, once again, would be a subjective process, even at 100 KIAS. I can't see authorities approving such a system unless it was able to be calulated for every take off. That would also require inputs for possible dragging brakes, airframe deterioration etc etc etc.
It's just not possible to do it accurately.
The issue here may well have had no different result if the wrong speeds were used. ie the acceleration to (your speed) of 100 KIAS would probably have been within a few seconds of normal.
The problem could have been trying to rotate the aircraft at much too slow a Vr. The aircraft just wasn't ready to fly. They would also have been above the "wrong" V1, and we are all trained to go after that speed.
As has been said before, it is an extremely dynamic situation and valuable seconds would have been taken in wondering why the aircraft wasn't responding. The rotation process over say 5 seconds would have consumed well over 1000 ft in itself, and probably much more with the drag of a continuous tail strike.
The hindsight committee will no doubt say they should have lowered the nose to the correct pitch attitude and immediately apply TOGA thrust. The crew on the night was faced with a situation that they had never ever seen before - so comment after the fact is of little consolation to them.
Time assessment on very heavy take offs, once again, would be a subjective process, even at 100 KIAS. I can't see authorities approving such a system unless it was able to be calulated for every take off. That would also require inputs for possible dragging brakes, airframe deterioration etc etc etc.
It's just not possible to do it accurately.
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To those who seem to think that the resignation of the pilots makes the results of the investigation fait acompli, this may or may not be true about the internal EK investigation but remember, there will also be an independent investigation by CASA. CASA has a pretty good reputation for independence and I would bet that "if" an error was made, the very next question will be "why". While I don't really expect much introspection from EK, I would by shocked if CASA refrained from looking into the human factors aspect of this.
It's just not possible to do it accurately.
Surely there could be a chart for your a/c type and engine configuration, down the Y axis is the N1 %, across the X axis is the weight, where they meet is the maximum time to 100kts.
Question for the performance types; how would the actual ambient temp be taken into account with something like this? Could you have bands of say "0-10degrees" 11-20 degrees, and 21-30 degrees, or would that be far too course?
Here is how I imagine it working; if for example you put the data into the laptop and it came out and said max time to 100kts is 35 seconds. You then trundle out to the runway and roll, at 35secs you notice you are only at 98kts, either abort or TOGA and off you go, if you get to 35secs and you are at 85 kts...abort.
I am looking forward to being corrected and having the weak points of this method pointed out as it will help me learn
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Physics
Not being a rocket scientist but Framers idea is quite plausible.
The other alternative as I said earlier is to use toga and those speeds for max TOW - that way ( almost) no take off becomes marginal ( except where you are below max structural- which in Emirates happens only in rare occasions).
Turning a high performance aircraft into a marginal performing one - which is what the current procedures end up doing.
Ask the punters if they want to pay an extra few dollars to use full power - or not... once again like telling them we fly slow and get them to places late when they have paid for a ticket - just to save fuel.
Granted, if you measure all variables with a micrometer - so that you can extend the field length out to a 'balanced field' ( where you can stop or go at V1 within the avail field) then this might save engine life etc but get any one of these wrong ( pax/pallet weights/bit more tailwind at one end of the runway etc) then all of a sudden you have no buffers left.
From basic newtons law stuff - s=ut+1/2 at.t
ut =zero therefore
at any point s=1/2 a. t squared.
a= comes from the accelerometers, therefore if constantly integrated over the changing values of acceleration a figure for time to get to a particular distance is really easy. ( yeah I know that is the trend vector)
All this information is on the jet....position/accel/et etc
I really think it would be possible to use the graphical method that Framer comes up with to come up with a gross error check point.
HOWEVER.... there is already gross error check points ( green dot/vref for the FMC weight etc) and these were ( possibly) not picked up.
Another possible and easy check would be for the performance figures to be pre calc'd for the ETOW by the company and transmitted on the OFP for the predicted take off conditions. or via acars. (Or.... even up linked like some operators)
This should be done on every takeoff to work out regulated anyway ( but it isn't where I work until the pilots do it for most takeoffs)
Would at least give some ball park numbers... but once again it has to be checked by someone ...
I think this is the point of all these possible solutions.... they still require a process to be followed.
Might reduce the swiss cheese holes but still wont stop the problem - just drive the stats out to past 1x 10-9.!
Anyway I really feel for the guys - these mistakes - if that is indeed what happened could happen to anyone of us.
We dont live in a perfect world the more we model it to suit ourselves the more it jumps back at us!
The other alternative as I said earlier is to use toga and those speeds for max TOW - that way ( almost) no take off becomes marginal ( except where you are below max structural- which in Emirates happens only in rare occasions).
Turning a high performance aircraft into a marginal performing one - which is what the current procedures end up doing.
Ask the punters if they want to pay an extra few dollars to use full power - or not... once again like telling them we fly slow and get them to places late when they have paid for a ticket - just to save fuel.
Granted, if you measure all variables with a micrometer - so that you can extend the field length out to a 'balanced field' ( where you can stop or go at V1 within the avail field) then this might save engine life etc but get any one of these wrong ( pax/pallet weights/bit more tailwind at one end of the runway etc) then all of a sudden you have no buffers left.
From basic newtons law stuff - s=ut+1/2 at.t
ut =zero therefore
at any point s=1/2 a. t squared.
a= comes from the accelerometers, therefore if constantly integrated over the changing values of acceleration a figure for time to get to a particular distance is really easy. ( yeah I know that is the trend vector)
All this information is on the jet....position/accel/et etc
I really think it would be possible to use the graphical method that Framer comes up with to come up with a gross error check point.
HOWEVER.... there is already gross error check points ( green dot/vref for the FMC weight etc) and these were ( possibly) not picked up.
Another possible and easy check would be for the performance figures to be pre calc'd for the ETOW by the company and transmitted on the OFP for the predicted take off conditions. or via acars. (Or.... even up linked like some operators)
This should be done on every takeoff to work out regulated anyway ( but it isn't where I work until the pilots do it for most takeoffs)
Would at least give some ball park numbers... but once again it has to be checked by someone ...
I think this is the point of all these possible solutions.... they still require a process to be followed.
Might reduce the swiss cheese holes but still wont stop the problem - just drive the stats out to past 1x 10-9.!
Anyway I really feel for the guys - these mistakes - if that is indeed what happened could happen to anyone of us.
We dont live in a perfect world the more we model it to suit ourselves the more it jumps back at us!
At CX we uplink the Takeoff data from the main frame in HK. We then enter it whilst carefully crosschecking the load sheet in a SET routine patter.
However, it is still possible to screw up the data entry and have both guys miss it.
We are only human after all.
The ONLY way is for the aircraft to weigh itself and come up with V1 VR and V2 numbers which if more than a few knots out wont let you enter the numbers from the RTOW calculations without giving you a clear warning message first.
Until this happens, no matter which way your company does it, there is no way to take out the "human error" aspect.
Just be slow and methodical, know you aircraft and what to expect.
However, it is still possible to screw up the data entry and have both guys miss it.
We are only human after all.
The ONLY way is for the aircraft to weigh itself and come up with V1 VR and V2 numbers which if more than a few knots out wont let you enter the numbers from the RTOW calculations without giving you a clear warning message first.
Until this happens, no matter which way your company does it, there is no way to take out the "human error" aspect.
Just be slow and methodical, know you aircraft and what to expect.