Details are emerging on the crash of Asiana Airlines Flight 214. It was most frustrating to watch talking heads speculate as to what had happened as we watched events unfold. Now the physics of the crash are out. I don't know how this story is being covered nationally, my local paper (The Contra Costa Times) has extensive coverage in it's paper edition.
Mostly, the story has been of the heroism of first responders and the flight crew -- truly amazing stuff -- like responders rushing up the evacuation slides to suppress the fire and rushing into the gaping hole in the back to rescue aged and injured passengers. And the possible tragedy that there's suspicion that a rescue vehicle may have hit and killed one of the two passengers to have died so far.
But this diary is about how was it that this plane ended up landing on the breakwater.
The Times diagrammed a timeline that showed the plane at 134 knots (just under target landing speed of 137) 34 seconds before the crash. The plane continued to lose speed until it was going 103 knots 3 seconds before impact. "At 1.5 seconds, pilots are heard saying 'go around'." But the 777s engines require 5 to 7 seconds to power up. "If it's what we think it is, he literally put himself in a position where he ran out of airspeed, altitude and ideas all at the same time." -- a spokesperson for a Texan aviation consulting firm.
Aviation experts told this newspaper that the timeline outlined by Hersman indicates the pilot may have turned off a system that automatically controls the airplanes's thrust -- called "auto thrust" or "auto throttle" that would have maintained the plane's target landing speed without the pilot having to do anything more.-- Contra Costa Times
The fact that the airplane was flying too slowly "makes me think that he expected the auto thrust to kick in, but it never did."
We'll have to wait to find out why that auto thrust feature wasn't working -- pilot error or malfunction.
UPDATE: Christian Dem in NC has a diary up: Asiana Flight 214 pilot had only 43 hours on Boeing 777. It's focus is on the training of the pilot and his instructor. It was the trainer's first flight as a trainer. However, the pilot had nearly 10,000 hours in other Boeing "heavies", like the 747 and 737 and in the Airbus A320.
I'm wondering if the autothrottle works differently in the 737.
The glidescope was not working on runway 28L. Did this make manual control required or was there another backup system? The NTSB chief added that the precision approach path indicator (PAPI), a light array next to the runway that also provides vertical guidance, was working properly. This system consists of three colored beams of light, the pilot sees red if the plane is below suggested flight path, green if above and white if on that path. So there was an aid if the pilot was flying without automated tools. But the important questions are, was the pilot forced to land the plane manually because of the non-functioning glidescope or because he was in training?
From the comments, James Fallows has more background on the 777. He speculates that if the flight got too high, the pilot may have gone into FLCH mode:
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.The light winds present that day may have put them unexpectedly high. SFO is usually a windy airport. If the pilots set up a rate of descent based on typical high winds, they would have found themselves further along and high during the descent -- necessitating FLCH mode.
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.