Turkish airliner crashes at Schiphol
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Flyinheavy posted:
"It appears there was more than an altimeter problem on the Turkish jet. Boeing said the autopilot system is designed so that if it senses faulty data from the captain's altimeter on the left side, the autopilot, including the autothrottle system that controls engine thrust, is supposed to switch to the altimeter on the right side used by the co-pilot. Boeing would not comment about what may have gone wrong on the Turkish jet, saying that is part of the investigation."
Seattle Post Intelligencer writes the above cited. Sheds a completely new light on the A/T system logic. The link to the complete article:
Not quite correct from my knowledge, though I am digging deeper and deeper into the design data.
Once again for those who keep missing it, the radio altimeter did not indicate a failure to the systems or the crew!! It incorrectly indicated a altitude of -8 feet, so the A/T thought it should be in the retard mode since the aircraft was in single channel A/P.
If the A/P had been in dual channel, this would not have happened as the A/T needs to have the flare discrete from the Flight Control Computers (FCC). Yes, there is a link between the A/P and A/T, but only in dual channel operation.
FCC A uses Rad Alt #1 as primary and FCC B uses Rad Alt #2 as primary. Since the aircraft was in CMD B, the #2 Rad Alt was feeding the A/P. However, the #1 Rad Alt was still feeding the A/T since it was not sending a fail flag (NCD on the 429 bus). The A/T thought all is well with the Rad Alt and therefore would NOT switch.
"It appears there was more than an altimeter problem on the Turkish jet. Boeing said the autopilot system is designed so that if it senses faulty data from the captain's altimeter on the left side, the autopilot, including the autothrottle system that controls engine thrust, is supposed to switch to the altimeter on the right side used by the co-pilot. Boeing would not comment about what may have gone wrong on the Turkish jet, saying that is part of the investigation."
Seattle Post Intelligencer writes the above cited. Sheds a completely new light on the A/T system logic. The link to the complete article:
Not quite correct from my knowledge, though I am digging deeper and deeper into the design data.
Once again for those who keep missing it, the radio altimeter did not indicate a failure to the systems or the crew!! It incorrectly indicated a altitude of -8 feet, so the A/T thought it should be in the retard mode since the aircraft was in single channel A/P.
If the A/P had been in dual channel, this would not have happened as the A/T needs to have the flare discrete from the Flight Control Computers (FCC). Yes, there is a link between the A/P and A/T, but only in dual channel operation.
FCC A uses Rad Alt #1 as primary and FCC B uses Rad Alt #2 as primary. Since the aircraft was in CMD B, the #2 Rad Alt was feeding the A/P. However, the #1 Rad Alt was still feeding the A/T since it was not sending a fail flag (NCD on the 429 bus). The A/T thought all is well with the Rad Alt and therefore would NOT switch.
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Whilst we may argue the benefits or otherwise of automation there is one area which could be improved quite drastically, that of the aircraft communicating to the crew what is going to happen.
Cast your mind back to Blake 7, if Zen thought it was a bad idea, it would tell you.
The current EGPWS database for example contains a simple digitised terrain map, unfortunately, because of the lead times between design and certification of such a system it’s probably early 90’s technology with only a few megabytes of storage and could benefit from the addition of a 16gb flash memory stick – problem 1 to be solved by the regulators – allow systems to be hardware upgraded quicker to allow for current technology/software.
So if you GPWS spoke in a firm voice and in good time “excuse me, but unless you climb immediately we are going to impact that mountain ahead 2000ft below the summit”, instead of yelling “pull up”, the crew might be able to understand their situation better.
Such a system would solve cultural respect problems evident in some countries, because the computer wouldn’t care who it was talking to, or in what manner.
Likewise, if two related instruments do not agree with each other, our computer voice might interject with “have you noticed the Captain’s Rad Alt, well my friend the auto throttle thinks we’re on the ground now etc etc”
It seems crews are often told there’s a problem by warning lights and horns, but in amongst what is explainable, what is false and what they are otherwise doing the accident that was preventable, happens, because they had to work out why.
We have the technology to do this now, but we must be quicker at certificating and then allow those systems to be upgraded more easily.
Cast your mind back to Blake 7, if Zen thought it was a bad idea, it would tell you.
The current EGPWS database for example contains a simple digitised terrain map, unfortunately, because of the lead times between design and certification of such a system it’s probably early 90’s technology with only a few megabytes of storage and could benefit from the addition of a 16gb flash memory stick – problem 1 to be solved by the regulators – allow systems to be hardware upgraded quicker to allow for current technology/software.
So if you GPWS spoke in a firm voice and in good time “excuse me, but unless you climb immediately we are going to impact that mountain ahead 2000ft below the summit”, instead of yelling “pull up”, the crew might be able to understand their situation better.
Such a system would solve cultural respect problems evident in some countries, because the computer wouldn’t care who it was talking to, or in what manner.
Likewise, if two related instruments do not agree with each other, our computer voice might interject with “have you noticed the Captain’s Rad Alt, well my friend the auto throttle thinks we’re on the ground now etc etc”
It seems crews are often told there’s a problem by warning lights and horns, but in amongst what is explainable, what is false and what they are otherwise doing the accident that was preventable, happens, because they had to work out why.
We have the technology to do this now, but we must be quicker at certificating and then allow those systems to be upgraded more easily.
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@737AvEng
That is not coming from humble myself. Thats an article from a Seattle media appearingly stating, that Boing is investigating why the automatic switching from RA1 to RA2 as A/T input did not take place.
Me too, I belived firmly that A/T would be "hotwired" to RA1. They are speaking of a possible software glitch!!????
Fh
That is not coming from humble myself. Thats an article from a Seattle media appearingly stating, that Boing is investigating why the automatic switching from RA1 to RA2 as A/T input did not take place.
Me too, I belived firmly that A/T would be "hotwired" to RA1. They are speaking of a possible software glitch!!????
Fh
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1/ I've only just managed to look at the data from the flight, and the generated flight path.
All technical and crew issues aside, one thing stands out to me.
In a typical weight 737-800 landing (not sure what flap was selected, let's assume F30) with the ROD and airspeed recorded, plus Ht above GS (see ROD), then the a/c would require flt idle until established around the 600' point ie they had excess energy to bleed off. My comment being, up to that point, it was a rushed approach, and you would not be expecting the TL's to increase if you were in MCP mode ie-no alarm bells at this point re A/T, except the Retard annunciatiation was missed. Understandable- they were rushed and trying to configure, c'lists etc, so 'normal' calm scan was absent. Therefore, comments about not noticing TL movement for 100sec are not relevant to this scenario.
The next 30 secs are the critical area, ie no thrust was applied to maintain Spd/GS/RoD.
2/ They were probably visual at 250', with 117 kts. and an 'OK' ROD. Any thoughts on an aggressive, correctly flown Stall Recovery manoevre-Ground Contact Imminent ???
This was missing
Forget 5deg PNU, it's AT/AP off, firewall (and keep 'em there in this case) , PLI's or intermittent Stick Shaker or 20deg, spd brake/wings lvl etc etc. and try and trade your way out with as much forward stick and trim as you can manage. There is a massive amount of power available-maybe too much fwd pressure if other hand has to keep pushing TL's up (ie missed step 1)-remember the stall sequences in the sim?
Just my 2 cents- but those manoevres at the back of the QRH are rarely given much Recall priority.
All technical and crew issues aside, one thing stands out to me.
In a typical weight 737-800 landing (not sure what flap was selected, let's assume F30) with the ROD and airspeed recorded, plus Ht above GS (see ROD), then the a/c would require flt idle until established around the 600' point ie they had excess energy to bleed off. My comment being, up to that point, it was a rushed approach, and you would not be expecting the TL's to increase if you were in MCP mode ie-no alarm bells at this point re A/T, except the Retard annunciatiation was missed. Understandable- they were rushed and trying to configure, c'lists etc, so 'normal' calm scan was absent. Therefore, comments about not noticing TL movement for 100sec are not relevant to this scenario.
The next 30 secs are the critical area, ie no thrust was applied to maintain Spd/GS/RoD.
2/ They were probably visual at 250', with 117 kts. and an 'OK' ROD. Any thoughts on an aggressive, correctly flown Stall Recovery manoevre-Ground Contact Imminent ???
This was missing
Forget 5deg PNU, it's AT/AP off, firewall (and keep 'em there in this case) , PLI's or intermittent Stick Shaker or 20deg, spd brake/wings lvl etc etc. and try and trade your way out with as much forward stick and trim as you can manage. There is a massive amount of power available-maybe too much fwd pressure if other hand has to keep pushing TL's up (ie missed step 1)-remember the stall sequences in the sim?
Just my 2 cents- but those manoevres at the back of the QRH are rarely given much Recall priority.
Last edited by vino; 6th Mar 2009 at 03:29.
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Turkish Airlines deny pilots reacted too late
Dutch press (ANP): Turkish Airlines stated that "if you read the report carefully, you conclude the pilots are not to blame". "When the speed is less than 250 km/h, there is nothing you can do. They were already at 178 km/h" according their spokesman. Turkish arlines say the Boeing 737's equipment was faulty. "There was nothing found wrong with the altimeter in the previous eight flights. Doing the maintenance inspections we followed Boeing regulations." (translated from Dutch)
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Does the 737 have a "Retard" annunciation? I thought that was an Airbus thing...
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Talking of distraction, how many of you, hand on heart, can honestly say that whenever you have a visit from the No. 1 or whoever else delivers the coffee to the flight deck in the cruise, that as PF studiously you did not turn around to look at whomever was there, did not listen to the banal conversation, did not chip in with your own 2 penn'orth and concentrated solely on flying the aircraft?
Whilst we accept, under the current training regime, that there should be a 'Safety Pilot' until such time as the trainee has the ability to fly the aircraft on his/her own, perhaps we should reconsider this aspect, as has been suggested; a review of all the training methods in use today.
It may well be that the third person in the cockpit is in fact a contributory factor in this instance and some of the other accidents we have discussed here. Maybe we need to insist on 2 crew aircraft flying with just 2 crew?
As to the events that occurred, it appears we now know pretty well the whole sequence of events. However, stall recovery when in the landing configuration with a ROD of 700 to 1000fpm is entirely feasable with minimal further height loss provided the stall recovery maneouvre is carried out PROMPTLY. (Try it in the sim, if we aren't all obliged to on our next visit!)
Agressively apply Full thrust and set 20 degrees of pitch.
20 degrees of pitch may require some forward pressure on the Control column once the pitch has been attained, however, even with the aircraft trimmed nose up due to the auto-trim funtion, it will not be impossible to hold this pitch angle. Height loss will be in the order of 100 to 200 feet if done correctly.
It appears that basic flying skills were forgotten.
The aircraft was put in a position from which the crew should still have been able to recover.
The situation was made hopeless because a fairly straighforward non-normal procedure was not followed.
What can we all learn from it?
As has been said so many times before, as is written on the top of every page of some airlines QRH, FLY the Aircraft.
Whilst we accept, under the current training regime, that there should be a 'Safety Pilot' until such time as the trainee has the ability to fly the aircraft on his/her own, perhaps we should reconsider this aspect, as has been suggested; a review of all the training methods in use today.
It may well be that the third person in the cockpit is in fact a contributory factor in this instance and some of the other accidents we have discussed here. Maybe we need to insist on 2 crew aircraft flying with just 2 crew?
As to the events that occurred, it appears we now know pretty well the whole sequence of events. However, stall recovery when in the landing configuration with a ROD of 700 to 1000fpm is entirely feasable with minimal further height loss provided the stall recovery maneouvre is carried out PROMPTLY. (Try it in the sim, if we aren't all obliged to on our next visit!)
Agressively apply Full thrust and set 20 degrees of pitch.
20 degrees of pitch may require some forward pressure on the Control column once the pitch has been attained, however, even with the aircraft trimmed nose up due to the auto-trim funtion, it will not be impossible to hold this pitch angle. Height loss will be in the order of 100 to 200 feet if done correctly.
It appears that basic flying skills were forgotten.
The aircraft was put in a position from which the crew should still have been able to recover.
The situation was made hopeless because a fairly straighforward non-normal procedure was not followed.
What can we all learn from it?
As has been said so many times before, as is written on the top of every page of some airlines QRH, FLY the Aircraft.
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Increased Use of Technology = Lack of Flying Skills
What Airline Management percieve as AVOID in the CRM Threat and Error model, i.e. policies mandating use of full automation, is now showing to have negative consequences through lack of RAW DATA flying skills.
This is evident at 6 monthly checks and, saidly, in real life when the last line in defence (swiss cheese model), the flight crew, cannot save the day.
Ok you may say, what about the Hudson River. Yes, but the captain grew up in aviation when RAW DATA was trained and a way to fly earlier aircraft.
The method now (or that perceived) is gear up AP ON .... Miniuma AP OFF. Do not touch the controls any other time other time, big brother is watching!
Just my 2 pence too ... oh credit crunch, sorry 1 pence now..
This is evident at 6 monthly checks and, saidly, in real life when the last line in defence (swiss cheese model), the flight crew, cannot save the day.
Ok you may say, what about the Hudson River. Yes, but the captain grew up in aviation when RAW DATA was trained and a way to fly earlier aircraft.
The method now (or that perceived) is gear up AP ON .... Miniuma AP OFF. Do not touch the controls any other time other time, big brother is watching!
Just my 2 pence too ... oh credit crunch, sorry 1 pence now..
Last edited by Capt Groper; 6th Mar 2009 at 05:03.
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There is NO SANE REASON to have the engines at idle for 100 seconds on ILS final! Either plan and execute the approach properly, or GO AROUND!
This is still a too regular occurrence (check your FDM rep for confirmation)-note- I'm not condoning it- but trainees will get TC's in this situation,TRE's will get other TRE's in that situation etc etc. The critical factor is when to bail out-push TOGA and away you go!!
That clearly didn't happen
Then the speed decayed-see earlier post!! Wouldn't matter if hand was on TL (and btw I agree)- PF is not expecting TL movement 'till on speed- which was much later.
That clearly didn't happen
Stall recovery required to be accurately flown from onset of stickshaker
That clearly didn't happen
And the biggest irony not yet mentioned- it was the high energy approach which most likely got them close enough to the ground before fully 'mushing in', which made the crash surviveable for so many.
Do you see my point? If they lost control from 2000' at <100kts it's hard to believe there would be any survivors.
Also, the failed/erroneous RA is actually directly involved in 2 aspects of the flight-
1/ the initial speed decay
2/ the stall recovery-ie it pulled TL back to idle again compromising an already marginal recovery.
Enough from me......
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I frankly don't know anyone now, who is comfortable disconnecting the autoflight system to fly an airplane. I know for certain that there have been a number of "close ones" precisely because of this lack of competency and understanding.
It is sad that we seem to be going the full circle with automation from hindrance to help to hindrance. Luckily I still fly for an airline which puts emphasis on stick and throttle skills.
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Galaxy @1438
Agree with your point. Intermittent failure in a radio feed is not at all uncommon in my experience. Especially when the antenna elements, power divider, and feed system operates in an environment with high temperature differentials and vibration. Which is why the sole burden for detection should probably not fall upon aircrew.
And by 'self test' I did not mean to imply only a start up or power on logic test. The technology has existed for years to detect VSWR faults in the antenna, feed, or connectors while the system is active. Again I hope the final report sheds light on the fault management regime and engineering decisions behind it.
And by 'self test' I did not mean to imply only a start up or power on logic test. The technology has existed for years to detect VSWR faults in the antenna, feed, or connectors while the system is active. Again I hope the final report sheds light on the fault management regime and engineering decisions behind it.
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There's a world of difference between 'failure' and outputting an incorrect value, in a system without checks and balances.
To sum up some points above, in my perspective:
Aircraft used to crash predominantly because their pilots couldn't navigate them. Now they crash because their pilots cannot fly them.
The industry really does need to get a handle on automation reliance, complacency, and flying skills...
To sum up some points above, in my perspective:
Aircraft used to crash predominantly because their pilots couldn't navigate them. Now they crash because their pilots cannot fly them.
The industry really does need to get a handle on automation reliance, complacency, and flying skills...
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BOAC, you haven't missed anything. With a radio altimeter inoperative the autopilot will disconnect 2 sec after LOC/GS capture.Thats what I was saying.
This happened at 2000' and from memory aren't the platform altitudes 2000' at AMS?
More system monitoring and less blame seeking I think without sounding an note of apportioning blame. As I have mentioned on the previous post, I have been laughed at for guarding the controls in my early days as an FO. Startle factor/lack of situational awareness in the final moments of an approach have been the highest contributors to CFIT accidents.
As for system modes its either all out or all in. Lots of crews are reluctant to disengage the AT completely(except on a line check)even though the SOP says so!
This happened at 2000' and from memory aren't the platform altitudes 2000' at AMS?
More system monitoring and less blame seeking I think without sounding an note of apportioning blame. As I have mentioned on the previous post, I have been laughed at for guarding the controls in my early days as an FO. Startle factor/lack of situational awareness in the final moments of an approach have been the highest contributors to CFIT accidents.
As for system modes its either all out or all in. Lots of crews are reluctant to disengage the AT completely(except on a line check)even though the SOP says so!
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I personally had an RA flag coming on during approach once in vmc conditions.Slightly high on spd. for the configuration.The fds flew off and PIT and ROL annunciated.All this approx. at 2000 ft. A/T remained engaged.The F/O was a fully qualified pilot with about 1000 hrs on type.The next 60 s was a flurry of activity,recycling the fds,engaging approach mode and configuring the aircraft for the landing( since we got distracted by the failure we were that much more out of the box as far as our approach was concerned).If we were not in vmc conditions and i didn't have an experienced first officer , i presume a go around might have been initiated.We landed comfortably without exceeding any approach parameters.
This accident reflects some significant differences
1.It was a training flt.The F/O was a low or no time on type pilot.The Capt.
was definitely overloaded once the RA flag came on.
2. The approach was in IMC.Not conducive to do training with a malfunction in the approach phase.
3.Two tech differences that I note is there is a mention of a ldg. gear warning horn and the A/T commanded retard if noted.Both of which would have added to the confusion and distraction.If the aircraft had switched to PIT mode as in my case it could have flown thru the G/S without capturing it esp. if it was below the G/S already.
4.The level of activity in the cockpit would have been enormous if attempts were being made to re engage automatics while there would have been no warning about the A/T retard except the FMA annun.How much the Tr. FO helped in this scenario remains to be seen.The role of the safety pilot appears to be more paramount in this case.As I am sure most trainers and some line pilots will bear testimony sometimes trainees freeze up at the wrong times .
5.To those who say throw out the technology,for every accident that occurs today ,i thank god for the tech. that has saved us day in and day out for which i can vouch for.The A/C warned of a malfunction ( RA flag) the AT annun. that it was in RETARD mode.What Boeing needs might be a in the face prioritise feature for the human element.
6 To the jokers who blame accidents on the big and small,fat and thin,black, white,yellow ,brown and anything i left out i just would like to say grow up guys.It has happened to the best of them and it can happen to you and me depending on the situation and the rest of them will discuss it threadbare over our bones.
7 To the old plane and the new plane flyers when it comes down to the brasstacks and you don't know what to do, just make sure you have speed and altitude.If you got too much of either give it to the other.
Cheers
This accident reflects some significant differences
1.It was a training flt.The F/O was a low or no time on type pilot.The Capt.
was definitely overloaded once the RA flag came on.
2. The approach was in IMC.Not conducive to do training with a malfunction in the approach phase.
3.Two tech differences that I note is there is a mention of a ldg. gear warning horn and the A/T commanded retard if noted.Both of which would have added to the confusion and distraction.If the aircraft had switched to PIT mode as in my case it could have flown thru the G/S without capturing it esp. if it was below the G/S already.
4.The level of activity in the cockpit would have been enormous if attempts were being made to re engage automatics while there would have been no warning about the A/T retard except the FMA annun.How much the Tr. FO helped in this scenario remains to be seen.The role of the safety pilot appears to be more paramount in this case.As I am sure most trainers and some line pilots will bear testimony sometimes trainees freeze up at the wrong times .
5.To those who say throw out the technology,for every accident that occurs today ,i thank god for the tech. that has saved us day in and day out for which i can vouch for.The A/C warned of a malfunction ( RA flag) the AT annun. that it was in RETARD mode.What Boeing needs might be a in the face prioritise feature for the human element.
6 To the jokers who blame accidents on the big and small,fat and thin,black, white,yellow ,brown and anything i left out i just would like to say grow up guys.It has happened to the best of them and it can happen to you and me depending on the situation and the rest of them will discuss it threadbare over our bones.
7 To the old plane and the new plane flyers when it comes down to the brasstacks and you don't know what to do, just make sure you have speed and altitude.If you got too much of either give it to the other.
Cheers
Per Ardua ad Astraeus
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Originally Posted by airbusa330
BOAC, you haven't missed anything. With a radio altimeter inoperative the autopilot will disconnect 2 sec after LOC/GS capture.Thats what I was saying. This happened at 2000' and from memory aren't the platform altitudes 2000' at AMS?
a) The autopilot (B, we are told) did NOT disconnect at 2000'
b) the autopilot (B) would NOT disconnect with a No1 radalt fail.
c) the radalt was not inoperative
This is getting so repetitive!
ant1 - in my Tech manual, at the end of automatic flight under min speed reversion. Very last lines.
in Fact is - knowing CNN I suspect they have just woken up................
Intruder - I think you actually asked about a RETARD annunciation? The answer is yes, a caption (only, no audio) at the top of the PFD but it is not very obvious.
ONEIN60 -PLEASE do us a favour!
@Intruder
Contrary to what a few others have said (their replies relate to Retard function) there is no aural 'RETARD' annunciation, which is what I think you were asking. There is a visual 'RETARD' on the FMA only, but if they failed to spot speed decaying to 40kts below Vref, then there is little chance that that would have been spotted. [I see BOAC has also highlighted that at the same time 
]
As regards 4 seats in the flightdeck of a 737, Rainboe is most likely correct with regards to BA's fleet of classics, but I would guess the 4th position installation would come down to the company's individual specification. I know our NGs have only 3 seating positions with seat harnesses. The metal pan behind the LHS is probably where the 4th position would be.
I have also been through the manuals as best I can, and I cannot see anywhere this Autothrottle logic as posted by Boeing recently where failure of the left RA automatically will cause a transfer to the right RA.
(And I realise that the left RA hadn't failed in this accident, rather it was giving an erroneous reading, before anyone bites my head off
)
Does the 737 have a "Retard" annunciation? I thought that was an Airbus thing...
]As regards 4 seats in the flightdeck of a 737, Rainboe is most likely correct with regards to BA's fleet of classics, but I would guess the 4th position installation would come down to the company's individual specification. I know our NGs have only 3 seating positions with seat harnesses. The metal pan behind the LHS is probably where the 4th position would be.
I have also been through the manuals as best I can, and I cannot see anywhere this Autothrottle logic as posted by Boeing recently where failure of the left RA automatically will cause a transfer to the right RA.
(And I realise that the left RA hadn't failed in this accident, rather it was giving an erroneous reading, before anyone bites my head off
)
Last edited by rhythm method; 6th Mar 2009 at 08:25.
@airbusa330
Are you are sure you aren't getting mixed up with autothrottle disengagement 2 seconds after touchdown?
BOAC, I am not sure if you are B737 or not, if you are, have you found anything in the manuals regarding the A/T logic of switching from left RA to right RA with a failure?
BOAC, you haven't missed anything. With a radio altimeter inoperative the autopilot will disconnect 2 sec after LOC/GS capture.
BOAC, I am not sure if you are B737 or not, if you are, have you found anything in the manuals regarding the A/T logic of switching from left RA to right RA with a failure?
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Question from a non pilot who has read all the thread.
Is the idle stop quoted in the report as being the position of the TL in Retard mode the same as the flight idle position?
Is the idle stop quoted in the report as being the position of the TL in Retard mode the same as the flight idle position?