Faulty RadAlt brought down Turkish Airliner

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Rubberbiscuit
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Faulty RadAlt brought down Turkish Airliner

Post by Rubberbiscuit »

Turkish Airlines crash due to faulty altimeter
Published: Wednesday 04 March 2009 14:32 UTC
Last updated: Wednesday 04 March 2009 14:42 UTC
The Dutch National Safety Board says the Turkish Airlines jet which crashed at Amsterdam's Schiphol airport on Wednesday had problems with its altimeter. The gauge wrongly indicated that the Boeing jet was nearly on the ground, prompting the autopilot to throttle back the engines.

Chairman Pieter van Vollenhoven said the pilots noticed the error but had no time to correct it. The altimeter in question had been defective twice before.

The safety board said the jet's flight manual should have included an instruction not to engage the automatic pilot in case of a defective altimeter. The board blames the Boeing factories for the oversight.

In the past week, the authorities have conducted an exhaustive investigation in and around the crashed passenger jet. The flight data and cockpit voice recorders were investigated at a specialised facility in Paris.

Nine people were killed and 80 injured in the crash at Amsterdam's Schiphol Airport. Twenty-eight of the injured are still in hospital.



To add some info, the autothrottles will start retarding to idle at 27'. The rad alt on the aircraft in question all off a sudden went from 1950' to -8' causing the throttle to retard. If it was a dual autopilot approach the aircraft would more than likely also have initiated a flare further aggravating the decay in speed. The crew also had an earlier clue indicating a problem when the radalt had casused the EGPWS to make a "to low gear" call.

Very unfortunate. I am not saying this crew did not do this, but it certainly puts in perspective the importance of having your hands and feet on the controls while closer to the ground. Our company policy is anytime below 3000' AGL.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Pratt X 3 »

Latest from the Aviation Herald:
http://avherald.com/h?article=41595ec3/0052&opt=0
Accident: Turkish Airlines B738 at Amsterdam on Feb 25th 2009, landed on a field
By Simon Hradecky, created Wednesday, Mar 4th 2009 13:59Z, last updated Wednesday, Mar 4th 2009 15:15Z

The Dutch Accident Investigators have revealed first results in a press conference in Den Haag today. With the exception of the left radio altimeter the Dutch Safety Board has not found any irregularities with the aircraft. The airplane was carrying 127 passengers and 7 crew. 9 occupants were killed in the accident, thereof 4 crew and 5 passengers. 28 of the injured are still in hospital care.

The captain was occupying the left hand seat, a fully qualified first officer occupied the right hand seat. For this first officer this was a training flight. Another first officer occupied the observer's seat. The airplane was performing an ILS approach to runway 18R on autopilot in fairly bad visibility according to standard operating procedures by Turkish Airlines. Mist and low cloud prevailed suggesting, that the crew most likely did not see Polderbaan (runway 18R) while commencing the final descent.

While the airplane was at 1950 feet MSL with the autoflight systems coupled to the ILS already, the left hand radar altimeter produced a wrong height reading of -8 feet. This resulted in the autothrottles to pull the thrust to idle. The landing gear warning horn sounded as a result of the erroneous reading, but was not considered to be a problem according to the cockpit voice recorder. However, this warning should have alerted the crew of a radar altimeter problem. The stick shaker activated at a height of about 500 feet AGL, at which point full power was applied. This however was already too late to recover the flight and the airplane subsequently impacted ground. The airplane hit ground with the tail first at a speed of 92 knots (normal landing speed would have been 140 knots) and slid for about 150 meters until coming to a stop. The airplane's tail broke off and the fuselage ruptured at the business class, the landing gear separated according to its design. The engines separated and continued for an additional about 250 meters due to the thrust they developed and the sudden deceleration of the airframe. The fatalities were mainly along the line of rupture through the business class. The cockpit crew was fatally injured mainly because of the enormeous deceleration forces and the nose wheel, that got partially embedded into the cockpit.

The flight data recorder stores 25 hours of flight data, which covered the last 8 flights of the airplane. During those flights another two failures of the left hand radar altimeter had been recorded. A Boeing Alert sent to all operators of 737s (all types) said, that no evidence of bird strike, engine or airframe icing, wake turbulence or windshear has been found so far. There was adequate fuel on board throughout the entire flights. Both engines responded normally to throttle inputs, the airplane responded normally to flight control inputs all the time. The digital flight data recorder indicated, that the autopilot B and autothrottle was being used for an ILS approach to runway 18R. The right hand radar altimeter was providing proper data, while the left hand radar altimeter provided faulty readings of -7 and -8 feet. The autothrottles, using the left hand radar altimeter, transitioned to the flare mode and retarded the throttles to idle thrust. The throttles remained at the idle stop for about 100 seconds, while the airspeed dropped to 40 knots below selected approach speed.

According to Boeing, if one of the radar altimeters provides erroneous height readings (regardless of whether the radar altimeter indicates itsself failed or not - failure flag or not), typical flight deck effects requiring crew intervention would be erratic radar altimeter readings on the instrument displays with differences between the two readings, inability to engage both autopilots in dual mode for the approach mode, unexpected removal of flight director bars, unexpected configuration warnings and a premature autothrottle RETARD annunciation on the pilots' primary flight displays.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by MUSKEG »

Ok I have to ask. What was the crew doing for 100 seconds while the throttles were at idle. I never liked mixing training with line flying. The training candidate had a tendancy to hesitate as he/she never knew if an exercise was simulated or the real thing. Even little things like instrument lag was questioned to see if it was real or induced.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Siddley Hawker »

Let me get this straight. Three cockpit crew sat there for twenty seconds shy of two minutes and watched the automated flight system fly their aircraft into a stall. :shock:
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Re: Faulty RadAlt brought down Turkish Airliner

Post by swordfish »

from rubberbiscuit:
but it certainly puts in perspective the importance of having your hands and feet on the controls while closer to the ground.
What we have here is clearly a case of the plane flying the pilots, rather than the other way round.

And as muskeg asked, what on God's green earth is happening after this happened? There should have been an instant cross-reference to the barometric altimeters, and an overshoot initiated. I would have expected that the crew (3 of them...hello...) would be scanning and cross-checking during any autoland. You don't sit there and watch the world fly by.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by MUSKEG »

To some in the younger crowd this whole exercise we call flying is about managing the video game. Some really struggled when the "auto" stuff went away.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Snowgoose »

Rubberbiscuit wrote: To add some info, the autothrottles will start retarding to idle at 27'. The rad alt on the aircraft in question all off a sudden went from 1950' to -8' causing the throttle to retard.
I'm going to have to go crack some books but why didn't they get a sink rate or terrain egpws warning with such a rapid change in rad alt?

Another thing, forget about the faulty rad alt. Why wasn't anyone looking at their airspeed?
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Jastapilot »

They should have had a rad alt flag. What I wonder is why they were doing an autoland with only a single autopilot engaged? I thought it had to be a dual A/P engagement for just such a problem?
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Re: Faulty RadAlt brought down Turkish Airliner

Post by swordfish »

why they were doing an autoland
Sorry. My conjecture, not established. Ignore.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Jastapilot »

It is established, not a conjecture at all. I just read they were using the B system autopilot to autoland with a faulty altimeter.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Jastapilot »

FROM: THE BOEING COMPANY
TO: MOM [MESSAGE NUMBER:MOM-MOM-09-0063-01B] 04-Mar-2009 05:29:01 AM US PACIFIC TIME
Multi Operator Message

This message is sent to all 737-100,-200,-300,-400,-500,-600,-700,-800,-900,-BBJ customers and to respective Boeing Field Service bases, Regional Directors, the Air Transport Association, International Air Transport Association, and Airline Resident Representatives.

SERVICE REQUEST ID: 1-1228079803
ACCOUNT: Boeing Correspondence (MOM)
DUE DATE: 10-Mar-2009
PRODUCT TYPE: Airplane
PRODUCT LINE: 737
PRODUCT: 737-100,-200,-300,-400,-500,-600,-700,-800,-900,-BBJ
ATA: 3400-00

SUBJECT: 737-800 TC-JGE Accident at Schiphol Airport, Amsterdam - 25 February 2009

REFERENCES:
/A/ 1-1222489391 Dated 25 February 2009

Reference /A/ provides Boeing's previous fleet communication on the subject event. The US NTSB, FAA, Boeing, the Turkish DGCA, the operator, the UK AAIB, and the French BEA continue to actively support the Dutch Safety Board's (DSB) investigation of this accident.

The DSB has released a statement on the progress of the investigation and has approved the release of the following information.

While the complex investigation is just beginning, certain facts have emerged from work completed thus far:

- To date, no evidence has been found of bird strike, engine or airframe icing, wake turbulence or windshear.
- There was adequate fuel on board the airplane during the entire flight.
- Both engines responded normally to throttle inputs during the entire flight.
- The airplane responded normally to flight control inputs throughout the flight.


The Digital Flight Data Recorder (DFDR) data indicates that the crew was using autopilot B and the autothrottle for an ILS (Instrument Landing System) approach to runway 18R at Amsterdam Schiphol airport. During the approach, the right Low Range Radio Altimeter (LRRA) was providing accurate data and the left LRRA was providing an erroneous reading of -7 to -8 feet. When descending through approximately 2000 feet the autothrottle, which uses the left radio altimeter data, transitioned to landing flare mode and retarded the throttles to the idle stop. The throttles remained at the idle stop for approximately 100 seconds during which time the airspeed decreased to approximately 40 knots below the selected approach speed.

The two LRRA systems provide height above ground readings to several aircraft systems including the instrument displays, autothrottle, autopilots and configuration/ground proximity warning. If one LRRA provides erroneous altitude readings, typical flight deck effects, which require flight crew intervention whether or not accompanied by an LRRA fault flag, include:

- Large differences between displayed radio altitudes, including radio altitude readings of -8 feet in flight.
- Inability to engage both autopilots in dual channel APP (Approach) mode
- Unexpected removal of the Flight Director Command Bars during approach
- Unexpected Configuration Warnings during approach, go-around and initial climb after takeoff
- Premature FMA (Flight Mode Annunciation) indicating autothrottle RETARD mode during approach phase with the airplane above 27 feet AGL. There will also be corresponding throttle movement towards the idle stop. Additionally, the FMA will continue to indicate RETARD after the throttles have reached the idle stop

Boeing Recommended Action
- Boeing recommends operators inform flight crews of the above investigation details and the DSB interim report when it is released. In addition, crews should be reminded to carefully monitor primary flight instruments (airspeed, attitude etc.) and the FMA for autoflight modes. More information can be found in the Boeing 737 Flight Crew Training Manual and Flight Crew Operations Manual.

Operators who experience any of the flight deck effects described above should consult the troubleshooting instructions contained in the 737 Airplane Maintenance Manual. Further, 737-NG operators may wish to review 737NG-FTD-34-09001 which provides information specific for the 737-NG installation. Initial investigations suggest that a similar sequence of events and flight deck indications are theoretically possible on the 737-100/-200/-300/-400/-500. Consequently the above recommendations also apply to earlier 737 models.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Flying Low »

Here comes another amendment to the aircraft manual!

"Boeing highly recommends that all flight crew fly the f%$#in airplane!"
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Re: Faulty RadAlt brought down Turkish Airliner

Post by FICU »

Jastapilot wrote:It is established, not a conjecture at all. I just read they were using the B system autopilot to autoland with a faulty altimeter.
Because the B channel was on with autothrottles doesn't mean they were attempting an autoland... The F/O, when PF, uses the B channel, for us anyway, and for an autoland both A and B must be engaged. This sounds like a single channel, "B", autopliot coupled ILS with autothrottles where by the crew weren't monitoring what they should have been.

Eerily similar to the Dash-8 accident in Buffalo. :shock:

Airspeed is life!
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Re: Faulty RadAlt brought down Turkish Airliner

Post by swordfish »

Airspeed is life
So is experience, attentiveness, diligence, focus, training, professionalism, and, last but not least, CRM.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Strega »

I wonder if these pilots had to do a 10 min presentation when they where hired?
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Re: Faulty RadAlt brought down Turkish Airliner

Post by youngtimer »

Rubberbiscuit wrote:Turkish Airlines crash due to faulty altimeter
Published: Wednesday 04 March 2009 14:32 UTC
Last updated: Wednesday 04 March 2009 14:42 UTC
The Dutch National Safety Board says the Turkish Airlines jet which crashed at Amsterdam's Schiphol airport on Wednesday had problems with its altimeter. The gauge wrongly indicated that the Boeing jet was nearly on the ground, prompting the autopilot to throttle back the engines.

Chairman Pieter van Vollenhoven said the pilots noticed the error but had no time to correct it. The altimeter in question had been defective twice before.

The safety board said the jet's flight manual should have included an instruction not to engage the automatic pilot in case of a defective altimeter. The board blames the Boeing factories for the oversight.

In the past week, the authorities have conducted an exhaustive investigation in and around the crashed passenger jet. The flight data and cockpit voice recorders were investigated at a specialised facility in Paris.

Nine people were killed and 80 injured in the crash at Amsterdam's Schiphol Airport. Twenty-eight of the injured are still in hospital.



To add some info, the autothrottles will start retarding to idle at 27'. The rad alt on the aircraft in question all off a sudden went from 1950' to -8' causing the throttle to retard. If it was a dual autopilot approach the aircraft would more than likely also have initiated a flare further aggravating the decay in speed. The crew also had an earlier clue indicating a problem when the radalt had casused the EGPWS to make a "to low gear" call.

Very unfortunate. I am not saying this crew did not do this, but it certainly puts in perspective the importance of having your hands and feet on the controls while closer to the ground. Our company policy is anytime below 3000' AGL.

Not to pick on the dutch NTSB, they could be right this time around, but they sure like to blame everyone else. Tenerife, 'faulty Q-400 landing gear;...
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Re: Faulty RadAlt brought down Turkish Airliner

Post by swordfish »

rubberbiscuit:
The crew also had an earlier clue indicating a problem when the radalt had casused the EGPWS to make a "to low gear" call.
Let me get this right: the crew flies a coupled ILS or an autoland with 1 autopilot, and a rad alt that has proven itself - on previous flights, and the current one - to be undependable, while failing to scan and monitor other dependable instrumentation in the conduct of a near-limits approach, then at the first indication of a serious anomaly, fails to execute a missed approach...and Boeing Aircraft Factory is at fault???

That's getting it as WRONG as it can possibly be, youngtimer.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by youngtimer »

yeah, I just didn't want to say it...you know those dutch :)
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Re: Faulty RadAlt brought down Turkish Airliner

Post by Jastapilot »

Rubberbiscuit wrote:To add some info, the autothrottles will start retarding to idle at 27'. The rad alt on the aircraft in question all off a sudden went from 1950' to -8' causing the throttle to retard. If it was a dual autopilot approach the aircraft would more than likely also have initiated a flare further aggravating the decay in speed.
Rubber, wouldn't the dual coupled autopilots have saved their asses? Wouldn't the system have disconnected or something if the rad alts had disagreed?
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Re: Faulty RadAlt brought down Turkish Airliner

Post by E-Flyer »

Oh Boy, another pilot error story is added to the statistics. :roll:

I mean, they create automation for simplicity, but when you DEPEND on that simplicity and in this case, fail to understand your systems to come up with a solution; 9 people will die.

I am still trying to figure out how the Ministry of Transport in Turkey recalls this accident as a "Miracle" since only 9 people died. Maybe my comprehension lacks lol :lol:
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Re: Faulty RadAlt brought down Turkish Airliner

Post by short bus »

strega wrote:
I wonder if these pilots had to do a 10 min presentation when they where hired?
Is that the best you got?

Think you need a good dose of what your avatar's selling.


p.s. - it's were, not where. Then again they probably told you that when you failed the presentation.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by HS-748 2A »

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Re: Faulty RadAlt brought down Turkish Airliner

Post by kilpicki »

How many of you have flown in the Arab world?

It still gets me when we hear ""landing in 15 min, Inshalla." on the radio
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Re: Faulty RadAlt brought down Turkish Airliner

Post by xsbank »

Flying Low has nailed it - the simple fact was that NOBODY WAS FLYING THE F*CKING AIRCRAFT!

Aviate, Navigate, Communicate. Has any pilot on this site not heard that before? Has anybody in a two-crew environment never had that rammed down their throats every recurrent?

That's the second airliner in 2 years that has thundered in, killing passengers, because there was NOBODY FLYING THE AIRCRAFT. The other was that Adam Air Boeing that dove from 29,000 feet, into the ocean, because both pilots were f*cking with the FMS. They ignored all of the warnings, the autopilot disconnect, the overspeed clacker, you name it.

Jeezus X. Christ. EGPWS. HGS. EVAS. FMS. FADEC. Glass. TAWS. It still took them 100 seconds to push up the friggin' throttles!

If anyone of you is so complacent that you can't pay attention during the approach, or below 10,000' for that matter, you need to go and get a real estate license and give up this job because you're in the wrong profession.

Inshallah my ass.
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Re: Faulty RadAlt brought down Turkish Airliner

Post by wooden spoon »

Both autopilot A and Autopilot B have to be engaged to do an autoland,which will enable after a self test,the flare maneuver.If only one autopilot was engaged.the aircraft would not have pitched up(ie flared)you can not do an autoland
in a NG with only one autopilot engaged.So with one autopilot(B) engaged,the only thing that in probability,should have happened would be the auto throttles would have retarded at 27'RA.as per the malfunction.So the aircraft was probably in a dual channel approach.both autopilots engaged.
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