Incident - Incorrect thrust setting for takeoff
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Assumed Temperatures, Flex Thrust etc
Framer, coming from the "steam driven" era I have not had any experience of all these modern techniques. In my day we determined Take-off data from the charts, used the thrust available for the barometric conditions (Flat rated up to 29 degrees C) and from that base determined what our limiting take-off weight would be for the runway to be used. We would de-rate if conditions and runway permitted, otherwise we used max available EPR for the take-off. In any event we had only three levels of de-rate. From what I read, given sufficient runway length the thrust set these days can be greatly below what is available. Also, the FE would compile the take-off data from the charts and the non-handling pilot would check the data. As I said, steam driven and, generally, less likely to allow gross errors to occur. I understand where you are coming from with your explanation and being unfamiliar as I am with modern practice I accept what you say. It seems to me that the old adage about computerised data stands i.e. "Garbage in - Garbage out"
Similar incident reported here:
Report: Arik B737 at Southend on Nov 21st 2010, takeoff with too low a thrust
Report: Arik B737 at Southend on Nov 21st 2010, takeoff with too low a thrust
Report: Arik B737 at Southend on Nov 21st 2010, takeoff with too low a thrust
By Simon Hradecky, created Thursday, Oct 13th 2011 18:53Z, last updated Thursday, Oct 13th 2011 18:53Z
An Arik Air Boeing 737-700, registration 5N-MJI performing positioning flight W3-6656 from Southend,EN (UK) to Lagos (Nigeria) with 2 crew, was taxiing out for departure from runway 24, when ATC changed the runway to 06 requiring the crew to reprogram the FMC with some urgency. The aircraft was subsequently configured for flaps 5, engine anti ice off and bleed air on. The aircraft backtracked runway 06 and began the takeoff run with the first officer being pilot flying. The captain thought acceleration was slow while the aircraft accelerated through 100 KIAS and called for maximum thrust. The aircraft rotated at 133 KIAS, became airborne before the runway end and continued to Lagos for a safe landing without further incident.
The AAIB released their bulletin reporting that during reprogramming the FMC after the runway change the FMC lost its performance data requiring to re-enter them. In the hurry the first officer entered an assumed temperature in the range of about 50 degrees C which was appropriate for most of the longer runways in his home country. However, with a takeoff distance available of 4785 feet for Southend's runway 06 the temperature was too high, an assumed temperature of 29 degrees C would have been correct.
The flight data recorder showed, that the engines had accelerated to about 80.9-81.9% N1 before the brakes were released for the takeoff run. The engines subsequently accelerated to 86.0/86.1% N1 within the first 500 feet of takeoff roll. The rotation was initiated at 133 KIAS and the aircraft became airborne at 140 KIAS and climbed through 35 feet about 4317 feet from the point of brake release. The aircraft crossed the runway end at 150 feet AGL.
A review of the aircraft performance using the assumed temperature of 50 degrees C showed, that had the crew elected to reject takeoff at V1, insufficient runway distance would have been available to stop the aircraft within the runway. The aircraft would needed 656 feet additional stop distance and therefore would have gone into the arrestor bed past the end of the runway overruning the end of the runway at about 60 knots.
Equally, had the aircraft suffered an engine failure at V1 and had the takeoff been continued insufficient runway distance would have been available to become airborne before the end of the runway.
The AAIB anaylsed that although the captain recollected calling for maximum takeoff thrust the FDR did not support that maximum takeoff thrust had been applied.
The AAIB analysed that both pilots were qualified aircraft commanders making it appear likely that mutual confidence into each other's abilities may have caused a break down in the monitoring of each other's tasks. Although the first officer called out the data he was programming into the FMC the captain did not notice the wrong assumed temperature.
By Simon Hradecky, created Thursday, Oct 13th 2011 18:53Z, last updated Thursday, Oct 13th 2011 18:53Z
An Arik Air Boeing 737-700, registration 5N-MJI performing positioning flight W3-6656 from Southend,EN (UK) to Lagos (Nigeria) with 2 crew, was taxiing out for departure from runway 24, when ATC changed the runway to 06 requiring the crew to reprogram the FMC with some urgency. The aircraft was subsequently configured for flaps 5, engine anti ice off and bleed air on. The aircraft backtracked runway 06 and began the takeoff run with the first officer being pilot flying. The captain thought acceleration was slow while the aircraft accelerated through 100 KIAS and called for maximum thrust. The aircraft rotated at 133 KIAS, became airborne before the runway end and continued to Lagos for a safe landing without further incident.
The AAIB released their bulletin reporting that during reprogramming the FMC after the runway change the FMC lost its performance data requiring to re-enter them. In the hurry the first officer entered an assumed temperature in the range of about 50 degrees C which was appropriate for most of the longer runways in his home country. However, with a takeoff distance available of 4785 feet for Southend's runway 06 the temperature was too high, an assumed temperature of 29 degrees C would have been correct.
The flight data recorder showed, that the engines had accelerated to about 80.9-81.9% N1 before the brakes were released for the takeoff run. The engines subsequently accelerated to 86.0/86.1% N1 within the first 500 feet of takeoff roll. The rotation was initiated at 133 KIAS and the aircraft became airborne at 140 KIAS and climbed through 35 feet about 4317 feet from the point of brake release. The aircraft crossed the runway end at 150 feet AGL.
A review of the aircraft performance using the assumed temperature of 50 degrees C showed, that had the crew elected to reject takeoff at V1, insufficient runway distance would have been available to stop the aircraft within the runway. The aircraft would needed 656 feet additional stop distance and therefore would have gone into the arrestor bed past the end of the runway overruning the end of the runway at about 60 knots.
Equally, had the aircraft suffered an engine failure at V1 and had the takeoff been continued insufficient runway distance would have been available to become airborne before the end of the runway.
The AAIB anaylsed that although the captain recollected calling for maximum takeoff thrust the FDR did not support that maximum takeoff thrust had been applied.
The AAIB analysed that both pilots were qualified aircraft commanders making it appear likely that mutual confidence into each other's abilities may have caused a break down in the monitoring of each other's tasks. Although the first officer called out the data he was programming into the FMC the captain did not notice the wrong assumed temperature.
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Tested the 80 knots by 1500 foot vs 80 knots by 1000' yesterday on 737. 80 knots occurred about half way between the two from a standing start , brakes release at toga button.....
Hence my assertion 80 knots by 1500.
Hence my assertion 80 knots by 1500.
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Don.
I appreciate where your coming from.
I don't fly the 737.
I wouldn't necessarily reject a takeoff if 80kts wasn't achieved by my own reference point. It's just a cue to consider my options if there was a significant difference.
Have you ever tried putting changes thru a flight technical department. In a lot of instances I've made submissions. The response is generally unless the data can be backed up from the manufacturer. Then a change or additional information in a training manual wont happen.
MC
I appreciate where your coming from.
I don't fly the 737.
I wouldn't necessarily reject a takeoff if 80kts wasn't achieved by my own reference point. It's just a cue to consider my options if there was a significant difference.
Have you ever tried putting changes thru a flight technical department. In a lot of instances I've made submissions. The response is generally unless the data can be backed up from the manufacturer. Then a change or additional information in a training manual wont happen.
MC
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Rules of thumb may give you a sense you are trying to do the right thing, however they will never cover all cases.
5 sec between 80kts & 100kts, if you are half a second out, that is a 10% error.
80kts by 1500' markers, thats fine if you don't have a displaced threshold or an intersection departure or a 4000m runway etc.
An accelerometer programmed for individual runway configs could be of use, but I don't know if these exists.
The only way is to ensure your data input is correct and independently verified.
Check your ATIS independently.
Calculate your take off weights independently, close your performance book (reset your EFB) after calculating your figures.
Write your figures on separate pieces of paper.
Then come together to check your differences.
TOLD cards can be an issue when pilots source data from them to calculate TO data as both pilots end up using the same incorrect data.
Finally, don't have pilots covering for other departments due to cost savings (load control etc) with the resulting time constraints affecting their ability to concentrate on the things that can kill people.
5 sec between 80kts & 100kts, if you are half a second out, that is a 10% error.
80kts by 1500' markers, thats fine if you don't have a displaced threshold or an intersection departure or a 4000m runway etc.
An accelerometer programmed for individual runway configs could be of use, but I don't know if these exists.
The only way is to ensure your data input is correct and independently verified.
Check your ATIS independently.
Calculate your take off weights independently, close your performance book (reset your EFB) after calculating your figures.
Write your figures on separate pieces of paper.
Then come together to check your differences.
TOLD cards can be an issue when pilots source data from them to calculate TO data as both pilots end up using the same incorrect data.
Finally, don't have pilots covering for other departments due to cost savings (load control etc) with the resulting time constraints affecting their ability to concentrate on the things that can kill people.
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438 -
http://www.onderzoeksraad.nl/docs/ra...C_Schiphol.pdf
The week before this incident.
On a takeoff from Miami, the Captain rejected the takeoff for unusually slow acceleration. I'm sure on the day in question data was independently checked, verified, briefed. ATIS independently checked, correct runway & weights used.
In this case the B747 was dragging the body gear brakes.
One can do everything correct in the flight deck, but unless there is an expectation of what acceleration is normal & what is not. There is no protection afforded against other subtleties like incorrect tyre pressure or dragging brakes.
A google search will highlight cases where a dragging brake & slower acceleration, coupled with gear retraction & wheel well fire has lead to a hull loss.
That expectation (what is normal & what is not) comes with experience. An experience in which Airline Executives & Training providers believe can be substituted by ensuring crew just comply with procedures.
MC
http://www.onderzoeksraad.nl/docs/ra...C_Schiphol.pdf
The week before this incident.
On a takeoff from Miami, the Captain rejected the takeoff for unusually slow acceleration. I'm sure on the day in question data was independently checked, verified, briefed. ATIS independently checked, correct runway & weights used.
In this case the B747 was dragging the body gear brakes.
One can do everything correct in the flight deck, but unless there is an expectation of what acceleration is normal & what is not. There is no protection afforded against other subtleties like incorrect tyre pressure or dragging brakes.
A google search will highlight cases where a dragging brake & slower acceleration, coupled with gear retraction & wheel well fire has lead to a hull loss.
That expectation (what is normal & what is not) comes with experience. An experience in which Airline Executives & Training providers believe can be substituted by ensuring crew just comply with procedures.
MC
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Finally, don't have pilots covering for other departments due to cost savings (load control etc) with the resulting time constraints affecting their ability to concentrate on the things that can kill people.
FSO's and INTAPs issued daily which are often changes and revisons to recent FSO's that shift responsibilty from the departments whose job (it used to be) to make sure those FSO's werent issued in the first place.
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I completely agree MC, I was just pointing out that little rules of thumb may not be the answer, otherwise they would probably be included in FCTM's. You always need to be prepared to firewall (TOGA) or reject if things don't feel right. The Jetstar AC came away unscathed so we don't know what rules of thumb they did or did not use.
My point being, do all you can to mitigate these events prior to rolling down the runway.
It can very easily happen to any one of us on any given day.
My point being, do all you can to mitigate these events prior to rolling down the runway.
It can very easily happen to any one of us on any given day.
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I think any pilot who has been doing it long enough would agree that good SOP's are important, but not nearly enough to ensure a safe outcome.
Rules of thumb help, as do "personal" SOP's that cover many potential traps that the manufacturer's SOP's and the airline's SOP's don't cover.
These personal SOP's come from experience.
An example is how to ensure all required actions and data entry is correct and complete following a late runway change prior to landing or takeoff.
Another example is how to pick up a gross error in ZFW. Do you know the basic weight of your aircraft? How often do you do a quick mental calculation of basic weight plus pax times 100kg plus freight to estimate the ZFW and compare it to the load sheet weight presented? I was taught that years ago by an ol-skool trainer and have never seen anyone do it since.
The quote above stating reasons for rejecting prior to 80kts including abnormal acceleration is all very well but it gives no guidance for detecting abnormal acceleration. That can only come from experience and vigilance.
But I'm told experience doesn't count any more as these new beaut machines pretty much fly themselves.
Rules of thumb help, as do "personal" SOP's that cover many potential traps that the manufacturer's SOP's and the airline's SOP's don't cover.
These personal SOP's come from experience.
An example is how to ensure all required actions and data entry is correct and complete following a late runway change prior to landing or takeoff.
Another example is how to pick up a gross error in ZFW. Do you know the basic weight of your aircraft? How often do you do a quick mental calculation of basic weight plus pax times 100kg plus freight to estimate the ZFW and compare it to the load sheet weight presented? I was taught that years ago by an ol-skool trainer and have never seen anyone do it since.
The quote above stating reasons for rejecting prior to 80kts including abnormal acceleration is all very well but it gives no guidance for detecting abnormal acceleration. That can only come from experience and vigilance.
But I'm told experience doesn't count any more as these new beaut machines pretty much fly themselves.
I think any pilot who has been doing it long enough would agree that good SOP's are important, but not nearly enough to ensure a safe outcome.
Rules of thumb help, as do "personal" SOP's that cover many potential traps that the manufacturer's SOP's and the airline's SOP's don't cover.
Rules of thumb help, as do "personal" SOP's that cover many potential traps that the manufacturer's SOP's and the airline's SOP's don't cover.
I imagine that greater discipline would prevent many of these incorrect thrust events because it would mean that SOP's were followed exactly.
Crews are under pressure from many different angles to achieve things in a certain time frame and strong discipline is needed to maintain healthy priorities.For example, if you have pushed back and started and an ATIS change requires new calculations but you are holding up someone elses taxi clearance what do you do?
A/ Hold them up while re calculating?
B/ Ask for a clear spot to do it in?
C/Get the F/O to do it on the taxi?
D/Not worry about it because you know the EFB only uses half the headwind anyway?
There are many different ways to deal with common situations like this but I imagine that often the independant calculation element of the SOP's is sacrificed, or there is significant distraction during the process as the crew try to do two things at once.
The same sorts of choices about priorities happen for different reasons throughout the pre-flight and taxi. A strong drive (discipline) to adhere to the SOP proceedure for performance calculations will keep you safe in these circumstances. Discipline can be built up, it can be lost, it can come and go depending on your state of mind, but if you practice it regularly it can also become habit.
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Interesting lot of technical stuff but what about the basics, CRM and monitoring each other, Why do we bother with two pilots up front in a critical phase of the flight and they both just sit there with puzled looks on their faces, this is all about disciplne and training, seems to an old stager like me that we are missing the point here????????
