@grebllaw123d

Well, if the RA showed -8, it is not failed (as far as the system goes), therefore the AP will not disconnect.. (I think)

cover page press release translation from Dutch
 

"Investigation Board warns Boeing for possible faults in radio-altimeter of Boeing 737-800

The Safety investigation board has warned aircraft manufacturer Boeing as a result of the first findings in the investigation of the Boeing 737-800 that crashed on 25 February 2009 shortly before landing on the polderbaan (red RWY 18R) of Schiphol airport. Because of a malfunctioning radio-altimeter the auto throttle, as part of the automatic pilot, received faulty signals. The president of the investigation board, prof.mr. Pieter Van Vollenhove, said on Wednesday afternoon that, while the aircraft was still flying at a an altitude of 1950 feet, de radio-altimeter indicated a height of minus 8 feet, so that the auto throttle retarded and also for the rest set the configuration as if the aircraft was positioned only a few meters above the runway. When the crew of the Turkish Airlines aircraft noticed what was happening, it was too late to effectively intervene.

Boeing has indicated that a warning will be sent to all operators of this type of aircraft, to alert them to this possible risk."

SR71

I aggree re he man/machine interface.

And re redundancy and failure detection: if you can't decide from two, you need three. Some digital instruments are smart enough to figure out when they're wrong (and the radalt seemed to have signalled just that, no?) in some other cases, you have a redundancy of three (like the airspeed indicators in the Birgenair case. Two on the main screens, one steam gauge somewhere else).

But that isn't my point really. The point is that, and you said it right: things fail, but they must either fail towards a safe mode or, if they fail to manual intervention, they must announce that completely unmistakeable.

The thing that I find shocking here is: surely the PF was required to have his hand on the throttles. If he had, he would have been fully aware of them going to idle, no?

Dutch Bru
 

Could you please clarify where the "trainee" was sitting? It's in the Dutch report but I'm not going to guess what it says. Thanks.

The aircraft I fly will always go into DUAL mode when passing 1200 ft RA.

How do you know? I can't find it in the books, nor have I ever had the A/P engaged below 50 feet on a single channel approach. (SOP, Boeing limitation)

Looks like Boeing is understandably upset with this crash. They're going to get sued yet the culprit are training and cultural problems. Stunning lack of airmanship here... "Welcome to the World of Turkish Airlines"

Can any radalt ever correctly indicate -8 feet? I would expect it to read 0ft with wheels on the ground, so a negative reading implies an error if not a detected failure.

No it actually reads -2 when on ground.
Because this way the RA will read 0 with a positive pitch attitude at touchdown.

Retard is an speed mode only and has nothing to do with autopilot nor automatic landing (which is actually possible single channel, just not approved). You will see the FMA announce RETARD even on manual landings.

According to the Boeing bulleting posted above it was not a dual coupled approach but a normal single autopilot approach flown on Autopilot B.

OK, thanks for that.

Is there any kind of cross checking between radar altitude and pressure altitude? That would provide a way of knowing which of a pair of disagreeing radalts was correct.

Nowhere is it said they were doing a CatIII Autoland.


CatIII Autoland training is done in the simulator, not on the line.


I believe the "Trainee" occupying the right seat was fully qualified after initial Simulator Training and was probably doing "Line Training" to complete his qualification. Or it may have been Annual Recurrent Line training.

The pilot in the jumpseat appears to have been un-qualified on this type and was only observing for educational purposes.

Dimiair - you'd better get in touch with Boeing to correct their MOM. PS Flare and retard are individual functions. Try leaving the A/T in to touchdown on a single channel/?visual? sometime.

FM - RadAlt normally indicates about -4 on the ground.

This all goes back to basic IFR-flying. Keep your hands on the throttle and look at your instruments :ugh: That´s the danger of full automation and of airlines who wants their pilots to fly on autopilot until the end...

It´s incredible that they didn´t notice the idle thrust for 100 sec and didn´t see that the speed was dropping to 40kts below the approach speed.. What were they doing??

According to the Turkish newspapers the pilots were heroes...
:ugh::ugh::ugh:

the_stranger, RA fail?
 

You have a good point - just misreading but NO FAIL flag.

So, flying on Autopilot B, suppose the right, on LOC and GS until stick shaker with the throttle retarded due to inputs from the misreading left radio altimeter.

brgds

Dysag:

Literal translation:

In the cockpit 3 people were present, the captain, seated left front. To his right was seated the F/O for whom this was a training flight. (The F/O held all licenses/qualifications) Another extra F/O was seated in the middle of the cockpit.

Automation caused the accident.
The only problem here was that the pilots did not in time figure out that it happened.

This is almost a copy of the 29th of December 1972, Eastern Airlines flight 401 accident in Miami. Two pilots and a flight engineer trying to fix a bulb and the aircraft parking itself in the Everglades.:(

Oh c'mon captain, we know you fly this exact kit, but in IMC and high workload, when did flying by the seat of your pants creep back as a requirement in commercial aviation??

Just for clarification:

Many where asking why the AT was doing the Autoland command sequence, while the AP was still tracking the glideslope and not going into FLARE (unannouced in FMA on a single channel approach)

We see here that AT was used in conjunction with AP/B on a single channel approach.

AP/B takes it's radar altitude from LRRA B, that worked fine.
AT takes RA only from LRRA A, regardless which Autopilot is enganged.
Even during a dual channel approach only LRRA 1 supplies data to the AT, that is because AT is a single channel system.

Anyhow... this was a major f**kup by the crew, sorry to say so...

What "cultural problem" are you referring to?