[gklitt]

I saw another image online, which compared the descent profiles of the past week of landings for the same flight. It showed that the July 6th landing was very close to the normal descent profile, and the July 5th landing was actually the outlier -- it had an unusually shallow glide slope.

Unfortunately I can't find the image right now, but perhaps someone else knows where it is and can provide it?

[vladd]

There are some at http://flyingprofessors.net/what-happened-to-asiana-airlines...

[RockyMcNuts]

like this link better than the OP which is fairly uninformed speculation ...

[RockyMcNuts]

some video of the crash - kind of looks like it was skimming the waves in ground effect trying to go around

http://www.cnn.com/video/?/video/us/2013/07/07/vo-plane-sf-p...

I stand by the parent having some useful data and analysis, and the OP being totally speculation, and in many respects uninformed.

- number 1, if you say 'loss of power', makes sense as a possible cause. if you say 'icing in the FOHE', it's like saying the murder was done with a yellow pistol. nothing points to that, no icing conditions (humidity/temperature), and of course not same engine as the previous plane crash attributed to that

- number 2, you can't be unaware of an ILS out of op, you wouldn't be cleared for the ILS approach, you wouldn't be using the ILS on visual approach, you would be cued there's no signal, you wouldn't hear the outer marker, etc. etc.

- number 3, auto-throttle, well again, if you say malfunction in power setting, OK could make sense, if you get as specific as 'confliction with autopilot/auto throttle' that's a purple pistol. Clearly not on cat3 autoland, you're basically saying pilot forgot to set throttle in the right configuration for visual approach and landing.

- number 4, pilot error/bad approach, can't argue with that. the story is what's interesting, eg undiagnosed walleye vision, ate the bad fish etc.

[VLM]

"- number 4, pilot error/bad approach, can't argue with that. the story is what's interesting"

Pilot induced oscillation on a really big scale. Coming in way too hot, slam down, whoops way over corrected, now coming in too low, whoops ran outta air and time to correct. Coming in way too hot, now are you better off trying to salvage or go around and get fired? Different nations airlines have differing policies on this...

[bajsejohannes]

Do you really risk getting fired for a go around? I mean, I can see that happening if you do it way more than other pilots, but just doing it once?

(For the record, I have no idea how these things works, it's just very surprising)

[RockyMcNuts]

I think you might get a call from a chief pilot for an anomalous approach, whether you salvage it at last minute or go around. If there's a pattern of things not going by the book, would guess you get sent for 'retraining' before you get fired... airline version of big data FTW I guess...

[justadude]

There may be some parallels between this and the crash which happened over London in 1999, see http://en.wikipedia.org/wiki/Korean_Air_Cargo_Flight_8509

[fnordfnordfnord]

>no icing conditions

Icing in the fuel lines may be caused by fluid flowing through an orfice (pressure differential). All that is needed is water in the fuel.

[RockyMcNuts]

water goes to the lowest point since it weighs more than fuel. then if it's not drained properly it gets sucked into the engine at the start of the flight. would be odd to discover water contamination after a long-haul flight.

I kind of assumed the FOHE was something that used external air, it wasn't water in the oil or the fuel. you descend through humid and coolish air ie not summer heat, water condenses and freezes as it's sucked through something from the pressure differential, or from actual icing conditions. but I could be wrong.

[fnordfnordfnord]

>water goes to the lowest point since it weighs more than fuel

While that's true, it takes time, and it won't get enough of the water out of the fuel[0]. Also, the aircraft must not be disturbed for the water to settle out. Operation demands for aircraft don't allow that. Even if they did, some water will remain in the fuel.

While the engines are operating, fuel is constantly circulating which disperses any water within the fuel. Airport fuel supplies at major airports are usually tightly controlled, but it's still be possible for water to get in.

>I kind of assumed the FOHE was something that used external air,

The FOHE is a Heat Exchanger, sort of like the radiator in your car, but instead of engine coolant/air the working fluids are Engine Oil/Jet Feul. Both the fuel and oil systems are closed systems, with one exception. As fuel is consumed in flight, the volume of that fuel must be displaced by outside air. Fuel tank to atmospheric pressure must never exceed some low differential pressure. This is one source of moisture ingress that must be dealt with, and can cause water to accumulate in tanks if left unchecked.

>you descend through humid and coolish air ie not summer heat,

Are you aware that the air temperature at altitude 35,000 ft is around -55C?

[0] http://www.petrolplaza.com/technology/articles/MiZlbiYxMDI3N...

edit: Here is a bunch of related photos if you're interested. http://englishrussia.com/2013/06/20/how-aircrafts-are-fueled...