Simviation Forum - Turkish Airliner Crash in Amsterdam

Reply #30 - Mar 4^th, 2009 at 8:45pm

Sytse Offline
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Virtual Red Arrows
The Netherlands

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Thanks for all the info huys. this really helps make a clearer picture.

Quote:

The autopilot on landing follows the ILS path. These are standard frequencies that are "beamed" out from the runway to show the aircraft the ideal glide slope to follow (the localiser and the glide slope) The autopilot takes these signals and follows them down to the runway........that was the simple answer. As for your flair question, only if the aircraft has autoland, otherwise the system will fly the aircraft without flair into the ground. Pilots don't like as a rule giving this bit of control away and go manual shortly before touch down. However in this case, if the crew were flying an autoland approach and an RA is inop, then certain autoland options are also inop, throttle retard on touch down for example.

The RA was not inoperative, but malfunctioning. So, the throttle retard is exatcly what happened, but the plane was still high in the air, in stead of touching down.

I don't know about the visibility, but it didn't seem very hazy on TV, only a little. People driving on the highway could see the plane in the air, just before it crashed. The clouds were very low though.

Charley, at what altitude (above ground level) are you flying when lowering the gear?

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Reply #31 - Mar 5^th, 2009 at 5:03am

expat Offline
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Deep behind enemy lines!

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Sytse wrote on Mar 4^th, 2009 at 8:45pm:

Thanks for all the info huys. this really helps make a clearer picture.

Quote:

The autopilot on landing follows the ILS path. These are standard frequencies that are "beamed" out from the runway to show the aircraft the ideal glide slope to follow (the localiser and the glide slope) The autopilot takes these signals and follows them down to the runway........that was the simple answer. As for your flair question, only if the aircraft has autoland, otherwise the system will fly the aircraft without flair into the ground. Pilots don't like as a rule giving this bit of control away and go manual shortly before touch down. However in this case, if the crew were flying an autoland approach and an RA is inop, then certain autoland options are also inop, throttle retard on touch down for example.

The RA was not inoperative, but malfunctioning. So, the throttle retard is exatcly what happened, but the plane was still high in the air, in stead of touching down.

I don't know about the visibility, but it didn't seem very hazy on TV, only a little. People driving on the highway could see the plane in the air, just before it crashed. The clouds were very low though.

Charley, at what altitude (above ground level) are you flying when lowering the gear?

The point here is the crew noticed that the rad alt was malfunctioning and did nothing about it and ignored three perfectly working altimeters. So if they noticed it, it should have been regarded as inop. Add to that if they could not clearly see the runway with the naked eye, they should not have been flying an approach on a single autopilot. Without wiring diagrams (I am at home), I cannot say what influence a malfunctioning RA would have had on the autothrottle, but the autothrottle has minimum speed protection when on the glideslope (other times too, but they are not in question). Also, autothrottle retard is at 27 feet RA, so the crew would be flaring to land some three to four seconds later. When in this time scale you have not touched down, well we will just keep faring, the runway must be somewhere under us???

Matt

PETA People Eating Tasty Animals.

B1 Boeing 737-800 and Dash8 Q-400

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Reply #32 - Mar 5^th, 2009 at 9:05am

C Offline
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Earth

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Sytse wrote on Mar 4^th, 2009 at 8:45pm:

Charley, at what altitude (above ground level) are you flying when lowering the gear?

Normally around 2000ft AGL, depending on the approach in question. Not many approaches are any lower.

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