EK407 Tailstrike @ ML
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Take-off power
As a SLF, I wonder why economics might influence the safety of the flight. We, all, agree that if maximum available power is used more fuel will be burned, lifetime of the engine will be reduced and tbo eventually reduced. The risk of overstessing the engines might induce failures.
On the other hand, if lesser runway is used, the chance of remaining on the runway after an aborted take-off close to V1 increases.
Shouldn't engines be operated at a compromise setting between maximum power and settings currently used?
I stand to be corrected and would appreciate to read comments from aero engines specialists.
Thks in advance.
On the other hand, if lesser runway is used, the chance of remaining on the runway after an aborted take-off close to V1 increases.
Shouldn't engines be operated at a compromise setting between maximum power and settings currently used?
I stand to be corrected and would appreciate to read comments from aero engines specialists.
Thks in advance.
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They already are. Take Off calculations already allow for a 15% increase in take off run plus a further third of the distance from airborne to 35 feet. How much more margin do you want, and would it make any difference if you've used the wrong weights in your calculations anyway?
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Not so many years ago now, I know of one (now ex-) 707 operator (military, southern hemisphere) whose SOPs on takeoff calculations were that one pilot prepared a set of figures, then handed the books over to the other with the book closed and no pages marked so that the the second pilot had to go through every step again himself, totally independent of the first.
Then they'd compare figures; and if they didn't agree, they'd look for the error.
On the EK 777 fleet, it was very easy to do something similar until progress intervened with the latest arrivals to the fleet not having the two inbuilt electronic flight bags. It was my habit, (and still is on the older aircraft fitted with the two EFBs), to do the takeoff figures myself, and then, with the very handy XFR button, I could very easily compare my figures with the FO's.
However, this doesn't address the problem of the wrong figures being put into the FMS, and I have to admit that I don't do it for every takeoff. On occasions, if there's the possibility of a runway change, I'll have the figures for the second runway in the other EFB pre start so as to save the FO having to be 'head down' inputting the new figures after taxi.
Having said that, I made a comment way back on page 1 of this or the other thread covering this incident that I'll repeat here, if not in exactly the same words. I think there'd be very few professional pilots who would not say "that could never have happened to me", even with every safety measure known to man in place.
As someone has said before me, the two operating pilots, how ever badly they may - (stress, at this stage, may) - have screwed up initially, did an excellent job in revovering the aircraft from the initial situation and then getting it back on the ground in one piece without injuring anyone among their passengers and crew, (I'm sure very ably assisted by the B crew).
I'd like to think I would be able to half as good a job as they did after the initial problem reared its head and pray to God I never have to.
Then they'd compare figures; and if they didn't agree, they'd look for the error.
On the EK 777 fleet, it was very easy to do something similar until progress intervened with the latest arrivals to the fleet not having the two inbuilt electronic flight bags. It was my habit, (and still is on the older aircraft fitted with the two EFBs), to do the takeoff figures myself, and then, with the very handy XFR button, I could very easily compare my figures with the FO's.
However, this doesn't address the problem of the wrong figures being put into the FMS, and I have to admit that I don't do it for every takeoff. On occasions, if there's the possibility of a runway change, I'll have the figures for the second runway in the other EFB pre start so as to save the FO having to be 'head down' inputting the new figures after taxi.
Having said that, I made a comment way back on page 1 of this or the other thread covering this incident that I'll repeat here, if not in exactly the same words. I think there'd be very few professional pilots who would not say "that could never have happened to me", even with every safety measure known to man in place.
As someone has said before me, the two operating pilots, how ever badly they may - (stress, at this stage, may) - have screwed up initially, did an excellent job in revovering the aircraft from the initial situation and then getting it back on the ground in one piece without injuring anyone among their passengers and crew, (I'm sure very ably assisted by the B crew).
I'd like to think I would be able to half as good a job as they did after the initial problem reared its head and pray to God I never have to.
"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."
Some of the -400 freighters are fitted with this weight and balance system. Perhaps it should be more widespread.
Some of the -400 freighters are fitted with this weight and balance system. Perhaps it should be more widespread.
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So you have seen the report Obie have you??? You are so far ahead of everyone else, muppet habibi!! Some colleagues are too quick to hang, draw and quarter their own, simply amazing 
SyB
SyB
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The old Vickers Vanguard ( Merchantman ) was fitted with a " STAN ",
I can´t remember what it stood for. However, as soon as the freighter
moved it displayed a rough indication of weight and trim, which was then
compared with the load/trim sheet figures. It worked perfectly and saved " big mouth ", one of our load controllers, from getting into serious trouble
when STAN indicated a ten ton weight difference. I know it wasn´t perfect, but it was helpful.
I can´t remember what it stood for. However, as soon as the freighter
moved it displayed a rough indication of weight and trim, which was then
compared with the load/trim sheet figures. It worked perfectly and saved " big mouth ", one of our load controllers, from getting into serious trouble
when STAN indicated a ten ton weight difference. I know it wasn´t perfect, but it was helpful.
As a brand new first-officer in his 1st airline job I was taught by my Training Captain, when the load sheet arrives,to ask yourself "what is V1 and is it logical"? Whilst this was a turbo-prop operation and didn't have the complications of rated thrust or assummed temperature methods or whatever it is called on the Airbus,I asked this question of myself throughout my career.
We know the empty weight of our aircraft,we know the approximate passenger load,(multiply by 100 KGS)we know how much fuel we want.So we know our approximate TOW before we even see a load sheet.The only large variable will be freight.If the difference between my estimated TOW and the load sheet is not the freight or extra passengers THERE IS AN ERROR.
While this method isn't fool proof and V1 can vary greatly with large TOW weight spreads and power settings and runway conditions,it eliminated the weight error possibility and made me think about the logic of my V1 speed.It worked for me throughout my time.
Of course none of this accounts for the added problems of duty time,time zone changes,accumulated fatigue,flight deck preparation interruptions,commercial pressure,company morale,flight operations department integrity,company operating procedures,flight planning,maintenance,MEL's and all the other distractions which the modern airline pilot has to deal with as part of his so called "normal operation".
It was a much safer flight deck preparation when we didn't tolerate interruption to this preparation.
Shooting the messenger will not fix the problem.
We know the empty weight of our aircraft,we know the approximate passenger load,(multiply by 100 KGS)we know how much fuel we want.So we know our approximate TOW before we even see a load sheet.The only large variable will be freight.If the difference between my estimated TOW and the load sheet is not the freight or extra passengers THERE IS AN ERROR.
While this method isn't fool proof and V1 can vary greatly with large TOW weight spreads and power settings and runway conditions,it eliminated the weight error possibility and made me think about the logic of my V1 speed.It worked for me throughout my time.
Of course none of this accounts for the added problems of duty time,time zone changes,accumulated fatigue,flight deck preparation interruptions,commercial pressure,company morale,flight operations department integrity,company operating procedures,flight planning,maintenance,MEL's and all the other distractions which the modern airline pilot has to deal with as part of his so called "normal operation".
It was a much safer flight deck preparation when we didn't tolerate interruption to this preparation.
Shooting the messenger will not fix the problem.
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Obie, if you say I "summed it up" with the message you read into my post, I have a serious communication problem.
I'm assuming you have your tongue firmly in your cheek with your following paragraphs.
I'm assuming you have your tongue firmly in your cheek with your following paragraphs.
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I've read every post in this thread that I can. As far as I can tell, nobody has asked this so far:-
Wouldn't safety be enhanced if every flight started as far away from the far end of the runway as possible? - i.e no starting from intersections with 300m of empty runway behind you.
It might not have made a difference in this accident, and I'm not sure whether or not they did start at the end or part way along the runway. Anyone else got that info?
Wouldn't safety be enhanced if every flight started as far away from the far end of the runway as possible? - i.e no starting from intersections with 300m of empty runway behind you.
It might not have made a difference in this accident, and I'm not sure whether or not they did start at the end or part way along the runway. Anyone else got that info?
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framer
You said : 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.
Which is exactly the point I was trying to make. If you do it this way it works - if you measure the time to 100 kts and discover it's actually 45 seconds not 35, what the heck do you do next? Can you be sure you have enough tarmac to stop?
It strikes me that if more departures are going to be made at reduced power using a bigger percentage of the available tarmac for economic resaons, then it's becoming essential to check the progress of the roll, other wise we're going to see more events like EK407.
You said : 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.
Which is exactly the point I was trying to make. If you do it this way it works - if you measure the time to 100 kts and discover it's actually 45 seconds not 35, what the heck do you do next? Can you be sure you have enough tarmac to stop?
It strikes me that if more departures are going to be made at reduced power using a bigger percentage of the available tarmac for economic resaons, then it's becoming essential to check the progress of the roll, other wise we're going to see more events like EK407.
Here's the spec. for a TakeOff Performance Monitor, published in 1987: sae.org I think that's what we're all asking for? If you have $61 to spare, you can even read it!
I haven't seen the document but I'd assume the problem is a little more complex than you might initially think. However, in these days of GPS and abundant storage/processing power, I'd have thought it would have been possible to construct a device that took as inputs the stabilised N1/EPR from the engines and the flap setting, measured the acceleration (and so determined the mass), then did a quick calculation from knowing (independently) where you were and where the end of the runway was.
If this calculation showed that you wouldn't get airborne in the length available, it would trigger a warning (possibly configuration?). If the warning system was set up so that it would only trigger on recognising a severe performance issue (= impending crash), then there would be much less likelihood of false warnings. The technology is there - certifying such a device is another issue completely...
I haven't seen the document but I'd assume the problem is a little more complex than you might initially think. However, in these days of GPS and abundant storage/processing power, I'd have thought it would have been possible to construct a device that took as inputs the stabilised N1/EPR from the engines and the flap setting, measured the acceleration (and so determined the mass), then did a quick calculation from knowing (independently) where you were and where the end of the runway was.
If this calculation showed that you wouldn't get airborne in the length available, it would trigger a warning (possibly configuration?). If the warning system was set up so that it would only trigger on recognising a severe performance issue (= impending crash), then there would be much less likelihood of false warnings. The technology is there - certifying such a device is another issue completely...
It's just not possible to do it accurately.
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I fly as an F/O on 742 and am a great fan of checking acceleration at 100kts. Though its not a simple calculation as altitude, wind, T/O weight as well as actual performance margin need to all be taken into account. I have an excel program which spits out a value for each Take off which I find accurate to about 3 sec. I start timing as we go through 60% and interestingly the acceleration times vary from 15 - 30 seconds ( I add 2sec for a static T/O ). The greatest variable I find is the F/E technique applying T/O thrust, a problem which won't occur on the new a/c using auto throttle for take off. As I'm in the right seat its will not be my decision to stop however I can at least inform the Capt if the acceleration is way off, possibly he may "feel" it too. I see it as a last resort strategy as I believe if you did mess the figures up you will "feel" that the accelaration is slow and now have a number you can compare it too. And can then make a reasonable decision based on the factors of the day.
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Ed,
All I can say is that the lawyers would have a field day if it went to court and all you were able to say is that "it looked right at 100 kts."
Interesting. I did it for 20 years and didn't realize that.
All I can say is that the lawyers would have a field day if it went to court and all you were able to say is that "it looked right at 100 kts."
The point of this check is to insert another safety mechanism on the takeoff roll, in order to prevent an aircraft becoming a very fast mode of ground transport.
In your example, the crew had chosen to commence the takeoff roll, meaning ipso facto that they were happy with their configuration and calculations to do so.
Without any intermediate check, they would have continued the takeoff roll anyway! By this (ficticious for the example) crew saying "...it looked right at 100 kts..." does not have a bearing on the outcome - they were going anyway! Thererefore legally it has no meaning.
The only way the 100 kt check can change the outcome of a departure is for the crew to abort the takeoff, turn around and have another go; after re-assessing their configuration and calculations. Hardly unsafe.
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oddly enough you say that, but in truth the 100 kt point is very telling, I always say 100 kts, 30 seconds, now that is my airplane, empty or full, a 747.
I say this because if I have not reached 100 kts by 30 seconds I know two things, either I have incorrect power set for the weight, empty or full, or I have a significant speed reduction, ie dragging brake, etc. Either way I know from time on type I may reach V1, but never VR in the confinements.
Rules of thumb are just that, a gross error check, but they serve the purpose to put doubt in your mind, and if I reach 100 kts and I am 20 seconds, I am stopping, if I reach 100 kts and I am 28 seconds I am very very observant. It cast doubt, and thats exactly what a rule of thumb is intended to do. It alerts you to impending disaster, and you react accordingly, I reach 120 and it still looks odd, I am now stopping.
beyond that, my options are limited.
Thankfully this has always carried me through, I have reached V1, and subsequently VR, albeit sometimes pretty far down the available surface, but it has worked.
I can say, from years of flying heavy aircraft, go oriented is a mindset, but the reality is always that the spread between V1 and VR can mean you may make V1, but never VR.
That is a reality I hope I never encounter.
I can well imagine what these guys saw, I hope to never see it, but I feel that gross error checks have their place, and it is exactly this scenario.
I cannot help but think that reliance on technology has pushed the gross error checks to the side, which may be a shame.
I would never dare to criticize the the crew involved, they acted on what was the information of the day. They now live and die by that inputted information, they undoubtedly believed in what they did at the time. I understand they were high experience, well established crew, unfortunately, as previously stated, you are as good as your last flight.
I suspect that training has shifted to reliance on given information, and it is very easy as crew to take face value information as gospel, I have seen it on occasion, the flight plan gives you a fuel, OK put it on, did you check it vs time and burn? no, it was on the plan, but they realize that they will never make destination.... after they depart.
A gross error check would have caught that, average burn VS FP fuel, for your weight.
We as crew are the final check, not dispatch, not load planners, because guaranteed when the flight goes all wrong, none of them are to blame.
The CPT signs the book, and will be fully accountable, and thats why in my back pocket I always hold a few gross error checks, they may seem old fashioned to those trained on glass, and fully reliant on given information, but they have served me well so far, and I have seen no compelling reason yet to give them up.
I say this because if I have not reached 100 kts by 30 seconds I know two things, either I have incorrect power set for the weight, empty or full, or I have a significant speed reduction, ie dragging brake, etc. Either way I know from time on type I may reach V1, but never VR in the confinements.
Rules of thumb are just that, a gross error check, but they serve the purpose to put doubt in your mind, and if I reach 100 kts and I am 20 seconds, I am stopping, if I reach 100 kts and I am 28 seconds I am very very observant. It cast doubt, and thats exactly what a rule of thumb is intended to do. It alerts you to impending disaster, and you react accordingly, I reach 120 and it still looks odd, I am now stopping.
beyond that, my options are limited.
Thankfully this has always carried me through, I have reached V1, and subsequently VR, albeit sometimes pretty far down the available surface, but it has worked.
I can say, from years of flying heavy aircraft, go oriented is a mindset, but the reality is always that the spread between V1 and VR can mean you may make V1, but never VR.
That is a reality I hope I never encounter.
I can well imagine what these guys saw, I hope to never see it, but I feel that gross error checks have their place, and it is exactly this scenario.
I cannot help but think that reliance on technology has pushed the gross error checks to the side, which may be a shame.
I would never dare to criticize the the crew involved, they acted on what was the information of the day. They now live and die by that inputted information, they undoubtedly believed in what they did at the time. I understand they were high experience, well established crew, unfortunately, as previously stated, you are as good as your last flight.
I suspect that training has shifted to reliance on given information, and it is very easy as crew to take face value information as gospel, I have seen it on occasion, the flight plan gives you a fuel, OK put it on, did you check it vs time and burn? no, it was on the plan, but they realize that they will never make destination.... after they depart.
A gross error check would have caught that, average burn VS FP fuel, for your weight.
We as crew are the final check, not dispatch, not load planners, because guaranteed when the flight goes all wrong, none of them are to blame.
The CPT signs the book, and will be fully accountable, and thats why in my back pocket I always hold a few gross error checks, they may seem old fashioned to those trained on glass, and fully reliant on given information, but they have served me well so far, and I have seen no compelling reason yet to give them up.
Finale?
Evertonian
Indeed Feather#3, as reported in our local rag which, by the way, has used ZK-EBC's photos & credited Pprune.org as the source!