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I wouldn't say "Autoland" to it but the 737's can do an "Automatic Flare/single channel flare" due to it's autopilot design. Even with A/P B engaged, the A/T recieves its inputs from FCC A and respective "A" radio altimeter, even if "B" channel is engaged. So if the A/T thinks it landing due to the erroneus RA input, very well possible to flare without any "Flare" FMA.
Pls correct, if my memory serves me wrong. |
Northbeach
'One Of Pax' posted this yesterday:
Hasan Tahsin Arisan : 55 years old. Graduated from military academy in 1976. Resigned from turkish airforces and joined THY in 1996. Known as a good instructor and being calm in emergency situations. Olgay Ozgur : 29 years old. Graduated from university in 2005. Started in World Focus Airlines. Transferred to THY in 2007. Had about 3000 flight hours. Murat Sezer : 42 years old. Resigned from turkish airforces and joined THY two years ago. Had about 3800 flight hours. |
Far be it for me to post in such a furious thread, but I can't help noticing that some people may be confusing the radio altimeter status.
A failure of RA channel 1 made the a/c go to power flight idle. Would you not agree that it either gives a reading or doesn't (ie. online or fail)? the fact that it gave a false reading does not mean that it had failed (in logic terms). In the case of a false reading, how does the AT know that it is false? It doesnt, I presume. In the event of a FAILURE of the radio altimeter certain conditions / configurations would not be allowed to exist, but as this wasn't a FAILURE, things carried on as 'normal' based on the (extraneous) data. Sorry for interrupting.... |
Evaluating liabilities
The Dutch report highlights the fact that problems with RA #1 were noted on two previous flights. Further, the report seems to imply that this information was apparently gleaned from FDR data rather than the aircraft's maintenance records which may indicate that previous problems with RA #1 may not have been written up in the maintenance log, and that no corrective maintenance action was undertaken nor MEL deferral made prior to the accident flight.
Can any current NG driver confirm the maintenance/deferral requirements under their MEL for a malfunctioning RA #1, with particular respect to continued use of the A/T system? Regards Edit: Northbeach, you beat me to it, sorry for the redundancy. |
I'd like to bring oldboldpilot's post 1116 to the top again.
Northbeach and others: Boeing state (quite clearly, to me) - see post 1063: "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." and that there is an "Inability to engage both autopilots in dual channel APP (Approach) mode" - with a u/s Radalt No dual channel, and I assume no autoland. MU - normally one is acceptable u/s for Cat I but autopilot that side not used for approach. |
Northbeach
The statement that after the A/T power reduction, caused by the radalt altitude change, the ensuing audible message was apparently not perceived as a problem (the crew were about to extend the gear at that point in the approach anyway) suggests that, the previous radalt faults may not have been perceived as a fault or indeed that the faulty radalt then immediately or after a short period started working normally. As such maybe no write-ups were made as it was not perceived as a problem? No doubt the FDR data will be further analysed to determine what happened during the previous radalt events. But it's possible that this was the first time that the radalt remained in the fault condition. |
The Rad ALt hadn't failed in the sense that it would display a large amber RA in the middle of the PFD. Instead it was giving an erroneous indication of -8ft. There is a subtle difference which has lead to the A/T system commanding thrust reduction. It wouldn't do this if the fail flag was showing.
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Question: was this crew flying an autoland approach? |
The R/A is not the cause of the crash... it's the ineptness of ALL three crewmembers in the cockpit.
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The R/A is not the cause of the crash... it's the ineptness of ALL three crewmembers in the cockpit. You have to look at the entire "system" which has resulted in this catastrophic failure. This would include, but not be limited to, a/c design, maintenance, airline safety culture systems, pilot selection and training etc. |
Radio Altimeter, Auto Pilot, Auto Land, Auto Throttles: NONE of this has anything to do with the fact that the CAPTAIN was NOT paying attention to two BASIC flight instruments; Airspeed and Altitude. If 'automation' FORCED his eyes away from those instruments, then we have a real problem, don't we? On the other hand, if 'automation' prevented him from taking corrective action to save his airplane, we have yet another problem!
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Agreed. The RA is a red herring. Interested parties will have their own spin, but the bottom line is the RA discrepancy needed only be a tech log entry and nothing more. Maybe a few seconds of confusion or 'arses and elbows' as it was dealt with, but the unexpected A/T mode should have been picked up on those big displays...
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I think it unfair to cast any blame on the jump-seater since we do not know at this stage in what capacity he was acting (I may have missed it!!). If he was 'safety pilot' then yes, he obviously failed. For all we know he could have been just using the j/seat to get to AMS.
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DANI:
How your tune has changed! Let me remind you of your assertion just a couple of days ago:
I asked you: DANI do you really believe this ac didn't stall on finals?????? You replied: FEHoppy, yes I do! So how does the prelim report support your theory? insert expletive here. |
Originally Posted by DC-ATE
On the other hand, if 'automation' prevented him from taking corrective action to save his airplane, we have yet another problem!
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Northbeach - flying an autocoupled approach does not mean that they WERE trying to do an autoland:ugh:
Seems to me basic scanning skills were remiss:suspect: |
I think it unfair to cast any blame on the jump-seater since we do not know at this stage in what capacity he was acting (I may have missed it!!). If he was 'safety pilot' then yes, he obviously failed. For all we know he could have been just using the j/seat to get to AMS. |
Since in this business what I don’t know can hurt me. And at the risk of looking uniformed………..here goes. On the 737 NG under what conditions, other than a dual channel autoland operation (autothrottles engaged), do the throttles come back to retard-not flight idle, but at the stops and annunciate retard and the aircraft begins to flare?
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routine use of autoland
fox niner: originally, the idea of using autoland in all possible circumstances was to get maximum experience with, and reliability statistics on autoland eliability. Tragically ironic in this case, it seems.
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At 27' RA normally if A/T is engaged, single or dual channel. FLARE is a separate function and nothing to do with the A/Throttles.
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