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737NG Radio Altimeter/Autothrottle/Autopilot Interface

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737NG Radio Altimeter/Autothrottle/Autopilot Interface

Old 8th Apr 2009, 16:10
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From what I read of the Turkish accident, the jumpseater was an F/O, which surely meant he had passed ground school, and could read English: "Radio Altimeter -1" on the Left (or #1) Radio bus.

I suppose pilots now are not taught systems architecture, either.

GB
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Old 8th Apr 2009, 17:38
  #42 (permalink)  
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To repeat:
"there is no way anyone I know would allow a 'jumpseater' to fiddle with a panel of 100+CBs when I am 'too busy',"

Now-a-days the norm is to monitor/agree switch/etc activation and not just 'have it done behind our backs', especially when the problem is not significant - and just flying the aeroplane would sort it out. Things have changed, I suspect.
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Old 8th Apr 2009, 19:47
  #43 (permalink)  
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Graybeard, it's totally unreal to even consider pulling CBs on final approach when the problem has probably only been identified at 2000'RA! I wouldn't even consider it without consulting the MEL and the QRH first, and no modern Boeing pilot would or should. It's a daft suggestion, especially getting a jump seater to start pulling CBs unmonitored! I really think it is not the time for a non-big jet pilot to tell us how to fly them!
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Old 8th Apr 2009, 23:18
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Iím not sure what some people are thinking here. There is a bigger picture to consider. If the crew fixated on the rad alt as much as it has been here, the aircraft would have been a smoldering wreck on the ground and many more would have died.
Autopilots and autothrottles are aids to the pilot. They are dependant on several sensors. Autopilot sensors like rad alts are not interconnected to each other so that each autopilot remains an independent system. One of the requirements for autoland systems is that autopilots remain independent of each others sensors electrics, and hydraulics.
Although aircraft components are highly reliable they still can fail at anytime. Additionally, when autopilots are used for approach, they rely on external signals beyond the control of the crew. These are not set and forget systems. At no time should the crew turn their attention away from making sure the aircraft is performing properly.
This aircraft was allowed to carry on until it had no capability to stay in the air. I donít know what was going on in that cockpit but I imagine it was far from what would be considered a textbook approach.
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Old 9th Apr 2009, 10:06
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Graybeard

From your posts you sound an experienced chap but I have to disagree with you when you state that pilots should be pulling CBs for an erroneous indication. The CBs are there to protect the wiring not the equipment and not normally to be used as switches.
They can be used as part of an emergency procedure to try and isolate equipment for something like fumes in the cockpit but these CB's tend to be the "generic" ones that when pulled isolate whole busbars.
Erroneous data should be flagged and then the subsequent action taken to isolate the specific sensor, ie switch to opposite side/disconnect AT and/or AP.

Most guidance material these days states that CBs that pop are to be reset once only, if they are required for continued safe flight and landing. If not critical then the crew should leave them popped, they did so for a reason. This is not directly related to you suggesting that they should be pulled on purpose during flight but it gives an indication of how cert authorities view the use of CBs.

Last edited by Nigd3; 9th Apr 2009 at 10:24.
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