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Originally posted by Stealthbomber
In my line of work if I make a mistake it can put a lot of people's lives at risk and it's always something that plays on your mind.
As US investigators interviewed the pilots of Asiana flight 214, a new picture emerged of a confused and chaotic situation inside the cockpit in the last 16sec before the Boeing 777-200ER's main landing gear caught the lip of the sea wall on the runway threshold at the San Francisco airport.
The captain flying, identified by Asiana as Lee Gang Guk, and the captain instructor, Lee Jeong-min, realized as they passed 4,000ft on approach to Runway 28 Left that they were "slightly high", says Deborah Hersman, chairman of the National Transportation Safety Board.
At that point, the crew set the vertical speed mode on the visual approach at about 1,500ft per minute, she says. But that descent rate brought the 777 down too fast.
As they passed 500ft, Lee Jeong-min, who was making his debut flight as a 777 instructor, noticed the three glowing red lights on the airport's precision approach path indicator that signaled they were slightly too low, Hersman says the captain told the NTSB.
That's the first thing I've seen suggesting the possibility something besides pilot error may be involved. I don't know anything about that system or how it works. At this point I suppose it could be either a problem with the autothrottle, or maybe the autothrottle didn't malfunction, but the crew wasn't familiar enough with how to operate it properly and they didn't have it enabled like they thought they did?
But the automatic speed protection system, for reasons that are still unclear, did not maintain the aircraft at 137kt.
The 777 can catch you out with with what is known as the "FLCH trap."
When you are above the glide slope and need to get down in a hurry Flight Level Change (FLCH) is a useful mode to use. Normally you transfer to another mode like glideslope or vertical speed, or you switch off the flight directors.
However in this situation the glideslope was off the air so the ILS would not have ben selected or armed. If the flight directors were left on and the plane was descending at a high rate in FLCH the autothrottle would have been inhibited and would not have put on power so the thrust levers would have stayed at idle.
The 777 has autothrottle wake up, ie when the aircraft approaches a stall the power comes on automatically to almost full power. This gives pilots great confidence however autothrottle wake up is inhibited in FLCH.
So 777 pilots will be looking at this scenario and wondering if Asiana were in FLCH with flight directors on, too high, stabilised late and did not notice they were still in FLCH and that the autothrottle was not keeping the speed to Vref plus 5 untl too late.
Originally posted by gariac
reply to post by _Del_
I guess I don't follow this article from the Atlantic. The glideslope is a radio signal. If you don't have it, I have to presume no control that uses it will operate. Further since glideslope and localizer are something you program into the receiver, the pilot would notice the glideslope isn't there. This is step one.
Originally posted by C0bzz
I'm surprised FLCH inhibits speed protection. That seems like a poor design choice or side effect of another design choice.edit on 10/7/13 by C0bzz because: (no reason given)
Originally posted by Zaphod58
reply to post by SheopleNation
Because the new fire trucks have a metal hose that can punch through the side of the plane and spray water directly into the cabin to fight an onboard fire.