I see that no fire and fuel is being questioned quite a bit on the various bloggs, well one thing does point to it, though there could be other reasons.

Notice any similarities in the two pictures.........no rotational damage to the fan blades?
However, like everyone else, I am speculating

Matt

Boeing 7777 G-YMMM


TK 1951

the spoilers were down,see the lead edge

There is a video released made by one of the passengers right after the crash. Emergency services still have to arrive.

http://www.hartvannederland.nl/item/19565/Eerste_beelden_van_net_na_de_crash

No news on the FDR/CR for as far as I know. They were sent to France to be examined. Speculations here are ranging from lack of fuel to that wake theory you mentioned.

Hagar wrote on Feb 28^th, 2009 at 7:43am:


Yes! Let's all jump straight to conclusions based on vague video material! After all, we all know how easy it is to keep thinking straight after being in an aircraft crash!




Anyway, there has just been a press conference with the first reports about the cause(s) of the crash.

The left radio altitude indicator was malfunctioning. It read -8 ft instead of 1950 ft. The right radio altitude indicator was working properly. The crew was using the auto pilot to land. The malfunction in the altitude reading caused the auto-throttle system to "think" it was right above the runway, so the power to the engines was reduced to idle. Because the plane was already very close to the runway, the pilots didn't respond to this as being a problem (throttle to idle is normal in the last stages of the approach). Only when the plane was beginning to stall did the crew react, but then it already was too late.

The plane hit the ground at 170 km/h and slid for 150 meters. The gear and engines snapped off, like they are designed to do in case of a crash landing. There were 127 passengers and 7 crew members on board. 4 American crew members and 5 Turkish passengers were killed in the crash. 28 people are still in hospital, one of them still in critical condition.

According to the data in the flight data recorder, the plane had trouble with the left radio altitude indicator before on two occasions. No further information about this is available at the moment.

A warning has been sent to Boeing about a section in the 737-800 manual, concerning the radio altitude indicators.

Sounds like a go-around as soon as the problem appeared may have been a prudent option. Time will tell, and from the comfort of an arm chair it is easy to say - the heat of the moment, far harder.

Sytse wrote on Mar 4^th, 2009 at 3:54pm:


To answer some of your questions;

There are two autopilots A&B. This has has nothing to do with the number of rad alts. The quick answer ,there are legal requirements laid down for autopilots and autoland. One of these requirements is two fully functional autopilots. They monitor each other along with several other functions.

The CAT's I,II,IIIA and IIIB&C are standards of ILS and visibility. I believe that the day in question was CAT II (requiring both RA's for autopilot approach).
Category I - A precision instrument approach and landing with a decision height not lower than 200 feet (61 m) above touchdown zone elevation and with either a visibility not less than 800 meters (2,625 ft) or a runway visual range not less than 550 meters (1,804 ft).
Category II - Category II operation: A precision instrument approach and landing with a decision height lower than 200 feet (61 m) above touchdown zone elevation but not lower than 100 feet (30 m), and a runway visual range not less than 300 meters (984 ft).
Category III is further subdivided
Category III A - A precision instrument approach and landing with:
a decision height lower than 100 feet (30 m) above touchdown zone elevation, or no decision height; and
a runway visual range not less than 200 meters (656 ft).
Category III B - A precision instrument approach and landing with:
a decision height lower than 50 feet (15 m) above touchdown zone elevation, or no decision height; and
a runway visual range less than 200 meters (656 ft) but not less than 50 meters (164 ft).
Category III C - A precision instrument approach and landing with no decision height and no runway visual range limitations. A Category III C system is capable of using an aircraft's autopilot to land the aircraft and can also provide guidance along the runway surface.
(Cut from Wiki)

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.

Why the autopilot put the aircraft into a stall, we don't have enough information about that, but I would guess that the crew did it in the last seconds. Noticed what was going on, fire walled the engines and then pulled back, but did not have enough hight to arrest the sink rate, but just a guess on that one.

The gear question, maybe Charlie will be able to answer that one.

As for the crew noticing that the RA no longer functioned when the gear was put down, they should have known that the autopilot was degraded at that point and that they should not make a CATII autopilot approach, as Charlie said earlier, a go around would have been a good idea and then work on the problem, that however is 20/20 hindsight on our part.

If as you say the runway was not visible (at any stage), a CATII autopilot approach with duff RA, big no no. They should have flow manual on the needles until decision hight and called it.

Flying the approach on autopilot is a company decision. The last company I worked for, an autopilot approach was company policy. The present company I work for the pilot has to manaully fly the needles once established or at the latest when the VASI's are seen.

Lastly, it would sound as if they where flying an approach with only one autopilot engaged because the system will be monitoring itself and would disengage if it found a large error.I hate to go on, but if that was the case, another no no under CAT II autopilot approach.

OK, now the disclaimer...........I am speculating a bit, we do not have all the facts outside of the regulations that I know and have to work with. Maybe other members who are air side can chip in too.  All information therefor is subject to amendment and correction as more facts are released about the accident.

Matt