C-FWGH 738 slow take off BFS : AAIB
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The incident and recommendation comes after a multitude of events.
In addition, it appears that the programming has now been made with efforts to attempts to trap even more errors made by the flight crew.
While many drivers claim the children of the magenta line mantra, with an over-reliance on the automation, it appears that much of the automation is has been put into place for a reason.
In addition, it appears that the programming has now been made with efforts to attempts to trap even more errors made by the flight crew.
While many drivers claim the children of the magenta line mantra, with an over-reliance on the automation, it appears that much of the automation is has been put into place for a reason.
All aircraft are liable to data entry errors. While this particular combination may not happen on the bus, there are plenty of other ways of killing yourself.
Load sheet and performance data is something that will kill you if you get it wrong and requires the utmost vigilance in entry and cross checking. I believe the 787 cross-loads data from the EFB performance function to the FMC which removes 1 avenue of entry errors.
Load sheet and performance data is something that will kill you if you get it wrong and requires the utmost vigilance in entry and cross checking. I believe the 787 cross-loads data from the EFB performance function to the FMC which removes 1 avenue of entry errors.
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Until recently, we didn't even enter the OAT into the FMC on the 777 where I work. We have been doing this for a while.
Is this error something specific to the 737 FMC/aircraft or would it cause the same type of thrust error happen in the bigger Boeing's as well. I know that there are some FMC differences as well as significantly different engines.
Is this error something specific to the 737 FMC/aircraft or would it cause the same type of thrust error happen in the bigger Boeing's as well. I know that there are some FMC differences as well as significantly different engines.
TPWS?
Given the nearly centimeter level accuracy of CAT ADS-B GPS sources, it would not take much math to predict engine out height over threshold given cumulative acceleration and runway position.
If less than 50' a stop alarm could be issued while there still remains adequate stopping distance. A fancier system would message the auto throttles to advance.
This could all be done with GPS and airspeed inputs completely independent of FMS.
Threshold Proximity Warning System
If less than 50' a stop alarm could be issued while there still remains adequate stopping distance. A fancier system would message the auto throttles to advance.
This could all be done with GPS and airspeed inputs completely independent of FMS.
Threshold Proximity Warning System
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Just like the RAAS system? Slavish adherence to it's long landing "guidance" mandating a go-around, as required by SOP's will almost certainly be a contributor to a 777 hull loss - Runway Impact During Attempted Go-Around despite there being ample runway available to stop.
This is not a simple plug-n-play fix. Humans make errors, software isn't context aware. We are a long way from solving our cognitive and software limitations.
As a side issue, I always cross check the FMC N1 against the EFB computed N1, most times it is incorrect when attached to an aerobridge on the NG (aspirated probes). Thus far, no one has been able to reason the source of this anomaly, in fact it is rarely questioned despite the consequences of an incorrect figure. After pushback, the computed and FMC figures resolve into agreement. Why? The answer is located on the upper DU.
This is not a simple plug-n-play fix. Humans make errors, software isn't context aware. We are a long way from solving our cognitive and software limitations.
As a side issue, I always cross check the FMC N1 against the EFB computed N1, most times it is incorrect when attached to an aerobridge on the NG (aspirated probes). Thus far, no one has been able to reason the source of this anomaly, in fact it is rarely questioned despite the consequences of an incorrect figure. After pushback, the computed and FMC figures resolve into agreement. Why? The answer is located on the upper DU.
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How it was explained to me on B777.
EFB value is correct. FADEC's static value is current aircraft configuration (bleeds off). FADEC (% or EPR) changes to correct value once engines started and recalculates with bleeds on.
EFB value is correct. FADEC's static value is current aircraft configuration (bleeds off). FADEC (% or EPR) changes to correct value once engines started and recalculates with bleeds on.
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Until recently, we didn't even enter the OAT into the FMC on the 777 where I work. We have been doing this for a while.
What about ISA DEV?
What do you do for FMC PERF INIT? and T/C OAT?
Last edited by underfire; 26th Sep 2017 at 02:33.
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It's actually quite simple, the aerobridge deflects airconditioned air (either aerobridge or cabin) which then escapes around the seal to the aircraft directing air close to the aspirated TAT probe. The TAT reading is correct, the air is not at the ATIS temp. On a hot day TAT under-reads, and cold morning TAT over-reads. This alters the FMC computed figure, and disagreement with the EFB. After pushback, the TAT again measures the ATIS OAT and the two figures resolve.
The really surprising thing is the lack of acknowledgment that the anomaly exists, and the lack of further questioning as to why. As I said, the answer is is on the upper DU, with a simple cross check of TAT vs ATIS to reason the source of the discrepancy.
Acceptance of discrepancies without question can lead to these types of incident.
The really surprising thing is the lack of acknowledgment that the anomaly exists, and the lack of further questioning as to why. As I said, the answer is is on the upper DU, with a simple cross check of TAT vs ATIS to reason the source of the discrepancy.
Acceptance of discrepancies without question can lead to these types of incident.
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On the 727 and 737-200 we used to always crosscheck the N1 and had a pre-calculated minimum value to be reached which was written down on the Takeoff data card.
The call made was "Takeoff thrust set-N1 checks". Something to consider doing, especially on the shorter or field limited runways with JT-8D engines.
The call made was "Takeoff thrust set-N1 checks". Something to consider doing, especially on the shorter or field limited runways with JT-8D engines.
Last edited by JammedStab; 21st Jan 2018 at 21:02.
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The call made was "Takeoff thrust set-N1 checks"
This was introduced on our B732 fleet after the Air Florida went swimming in Potomac. Same reason, blocked pitots, but via a different cause. In this AB event was in not a case of rubbish in rubbish out; i.e. wrong assumed temp entered in EFB. Cross checking the N1% for the Temp would have provided the correct corresponding answer, but still too low thrust. What was being discussed is too many modern pilots don't have a mental model with which to make gross error checks. I doubt these guys had ever taken off, even of a ferry flight, with N1% <90%, yet on this day it is reported they tried to do so. An error was made, I assume by one guy, and no bells rang for either of them. How to prevent it? Some say that the EFB should have an error alert program in it. I know some airlines where both pilots do the performance calculation independently and x-check. I'd like to see better awareness trained into pilots as well. Aviation hasn't changed that much with the advent of computers over pencil & rubber & tables. It is the same dumb humans who execute the tasks. The more complacent we become with "it's a computer so it must be correct" the more accidents of this nature we will have. After 30 years of FMC, pilots have developed a wise suspicion of VNAV profiles. They spot crazy things happening. If the FMC can be suspect and thus encourage gross error checks, why not EFB's? Too old school?
I'm amazed that some pilots are so keen eyed that they spot N1% increasing after takeoff when CLB power is selected. They often ask the reason, and can not always find the answer (it's been discussed for years on Tech Log) but at least they noticed. That's great, and we need more pilots who observe and ask questions about things that don't seem correct.
Isn't that part of our job?
This was introduced on our B732 fleet after the Air Florida went swimming in Potomac. Same reason, blocked pitots, but via a different cause. In this AB event was in not a case of rubbish in rubbish out; i.e. wrong assumed temp entered in EFB. Cross checking the N1% for the Temp would have provided the correct corresponding answer, but still too low thrust. What was being discussed is too many modern pilots don't have a mental model with which to make gross error checks. I doubt these guys had ever taken off, even of a ferry flight, with N1% <90%, yet on this day it is reported they tried to do so. An error was made, I assume by one guy, and no bells rang for either of them. How to prevent it? Some say that the EFB should have an error alert program in it. I know some airlines where both pilots do the performance calculation independently and x-check. I'd like to see better awareness trained into pilots as well. Aviation hasn't changed that much with the advent of computers over pencil & rubber & tables. It is the same dumb humans who execute the tasks. The more complacent we become with "it's a computer so it must be correct" the more accidents of this nature we will have. After 30 years of FMC, pilots have developed a wise suspicion of VNAV profiles. They spot crazy things happening. If the FMC can be suspect and thus encourage gross error checks, why not EFB's? Too old school?
I'm amazed that some pilots are so keen eyed that they spot N1% increasing after takeoff when CLB power is selected. They often ask the reason, and can not always find the answer (it's been discussed for years on Tech Log) but at least they noticed. That's great, and we need more pilots who observe and ask questions about things that don't seem correct.
Isn't that part of our job?
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Why a certified, calibrated accelerometer is not part of a modern jet aircraft instrument panel I'll never understand. It's a bottom line performance indicator.
I imagine most PF would consult it at about 80 knots on short runways take-offs. No?
I imagine most PF would consult it at about 80 knots on short runways take-offs. No?
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30+ years of check and training experience says one thing to me. This is a training issue... even probably a 'pilot selection' issue. And fundamentally, a regulator issue.
It starts with more than 'I have £100k, please make me a pilot' and should absolutely ensure that at 'ab-initio' and 'basic' flying training, commonsense and 'natural' pilot aptitude is followed up right through a pilots career/training.
Yes, we need more pilots and the demand for pilots is ever increasing. But this incident is a hairs breath away from yet another totally avoidable hull loss...
History is littered with similar incidents/accidents. The time will come where we reach tipping point on 'dumming' down selection and training versus front page 'newspaper' reports of yet another accident.
Do we have to wait for this? The 'threat' is clear. Lets do something about it now. There are more and more threat signals every year. That response must also include by-passing commercial pressures and e.g.: share and stakeholder budget cutting 2% YOY, in training and regulation. The industry at large, will be much better off as a result.
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Bob gric
Excellent post home truths.
Pilots in the past had to have the ability & ability to have empathy & “gut” feeling of what the aircraft is doing. £100k does not give you that. Unfortunately too many are coming into the industry, because anyone can be a pilot can’t they. (Piece of cake old boy) well actually no.
Excellent post home truths.
Pilots in the past had to have the ability & ability to have empathy & “gut” feeling of what the aircraft is doing. £100k does not give you that. Unfortunately too many are coming into the industry, because anyone can be a pilot can’t they. (Piece of cake old boy) well actually no.
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Yes it does, yes we do.
But it still won't tell if it is wrong, if the wrong temp is inserted in both EFB & FMC. If there is some kind of x-check that the ATIS OAT is inserted in the boxes you may pick up an error. But no pilot should be content to attempt to takeoff with <90%. That's gut feeling at least; surely. nd it's 2 pilots who stopped thinking, not just one.
What has dismayed me is the dilution of basic airmanship in TR courses for cadets. The rapid expansion of young airlines has needed qualified bums on seats up front PDQ. Guys leaving after a few years experience faster than they can be replaced, and the expansion covered as well. Fair enough, you pass the LST, but the education then stops. SOP's designed for trained monkeys and then 3-4 years later you are sitting in LHS with not much to pass on to the newbie in RHS. Both of you are locked onto an SOP train line where you hope there will be no sharp bends, overheated this or that and definitely no 'wrong kind of leaves' on the line. Previously you would have waited and served an apprenticeship for 7 years in RHS, seen a lot and hopefully soaked up and learnt a great deal. You had the confidence that you could handle the a/c on an ideal day, lead the crew, manage the operation and cope with a few hiccups without having to think SOP first & airmanship/common sense second.
But it still won't tell if it is wrong, if the wrong temp is inserted in both EFB & FMC. If there is some kind of x-check that the ATIS OAT is inserted in the boxes you may pick up an error. But no pilot should be content to attempt to takeoff with <90%. That's gut feeling at least; surely. nd it's 2 pilots who stopped thinking, not just one.
What has dismayed me is the dilution of basic airmanship in TR courses for cadets. The rapid expansion of young airlines has needed qualified bums on seats up front PDQ. Guys leaving after a few years experience faster than they can be replaced, and the expansion covered as well. Fair enough, you pass the LST, but the education then stops. SOP's designed for trained monkeys and then 3-4 years later you are sitting in LHS with not much to pass on to the newbie in RHS. Both of you are locked onto an SOP train line where you hope there will be no sharp bends, overheated this or that and definitely no 'wrong kind of leaves' on the line. Previously you would have waited and served an apprenticeship for 7 years in RHS, seen a lot and hopefully soaked up and learnt a great deal. You had the confidence that you could handle the a/c on an ideal day, lead the crew, manage the operation and cope with a few hiccups without having to think SOP first & airmanship/common sense second.
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Until recently, we didn't even enter the OAT into the FMC on the 777 where I work. We have been doing this for a while.
Is this error something specific to the 737 FMC/aircraft or would it cause the same type of thrust error happen in the bigger Boeing's as well. I know that there are some FMC differences as well as significantly different engines.
Is this error something specific to the 737 FMC/aircraft or would it cause the same type of thrust error happen in the bigger Boeing's as well. I know that there are some FMC differences as well as significantly different engines.
But it still won't tell if it is wrong, if the wrong temp is inserted in both EFB & FMC.