Doug's find on Asiana SFO crash

Since you mentioned NTSB and Twitter, they did release some photos of the interior of Asiana 214 at NTSB (NTSB) on Twitter.

Too bad there aren't yet any photos of the burned interior sections.

 

Very impressed with the news conference with the NTSB officials. Quick assessment of the situations and contributing factors. Very positive and enlightening. Contrary to the government hearings we've seen on TV the last few months. Ask a direct questions, you get no answer, indirect answer, or I'll check and get back. Not to be totally negative, but I've lost faith in most of our government, elected officials, and employees to be honest, up front, and provide the services they're paid to provide. Thanks NTSB.

 

I spent 25 confusing minutes watching CNN, reporters calling it the "Hull" of the aircraft, bad eyewitness accounts, got really tired and as I was changing channels to FOX, I mentioned, on observing the debris trail, to my wife, "YOU CAN'T LAND SHORT AT SFO" then Fox pops up, within 1 minute the Pilot they were interviewing summed it up as "You can"t land short at SFO" Within the next 10 minutes Fox had just made CNN's 25 prior coverage sadly amusing.Sometimes FOX has the RIGHT people speaking!!!
BTW, aircraft have a "Fuselage"
Boats and Ships have "Hulls"

 

From preliminary reports it seems like they came in low and slow- that is below the glide-path that would place them on the runway and too slow to the point where they were about to or actually did stall (stall is the airspeed where the wings/lifting surfaces have insufficient airflow over them to produce lift). Passengers said they could hear the engines spooling up (to give the aircraft more airspeed and altitude) as they were on final approach and close to the runway threshold which would support the low and slow theory. Any pilot trainee with at least one landing under his belt can tell you low and slow is not a good situation to be in.... especially on final approach only a few hundred feet from the ground.
Other than loss of engine power or inclement weather it's almost inconceivable that a short landing could happen on a modern jet aircraft with a professional crew.



FWIW- pilots do train for "low and slow" situations on final approach- if you're still some distance from the runway (a couple of miles out or more for larger aircraft) you can add throttle and stay at the same altitude till you intercept the correct glide-slope again, or if you're too close to the runway- throttle up, retract the flaps and landing gear and do a "go around" where you basically continue flying straight over the runway then turn right or left at the end and re-do your whole approach but this time at the recommended airspeed and altitude profile.

 

Bob put the flying professors link, which was pretty good (we both thought) Beyond that

I would like to stress that the Asiana cabin crew did an exceptional job in evacuating the aircraft, and that SFO responders did an exceptional job in handling injured passengers. Working so well under such circumstances is something that none of us here can probably imagine.

The most revealing (Fred Hayes) video shows the aircraft too low and nose-high approaching the runway threshold, with white plumes from the water surface (this is an over-water approach). This has been interpreted as blown by engine exhaust, or dragging the tail in water. Neither can be excluded now. The tail (at least) hit the rip-rap sea wall, to the right of runway 28L centerline. If some part the main landing gear is in the water, it would demonstrate additional sea-wall strikes.

After that, video shows the aircraft (having lost its tail) to go further nose high, lift a wing, yaw sharply, and fall onto on the runway. None of that could have been under pilot control; they had also become passengers at that point.

Flying professors' analysis is based on radar returns via FlightAware, and the data accuracy is not guaranteed. There is also another data source; ADS-B:

Automatic dependent surveillance-broadcast - Wikipedia, the free encyclopedia

I took ADS-B data from the ‘professional pilots’ rumors‘ website discussions page. It looks like this:

LATLONG HDG (magnetic) UTC ALTGS(ground speed in knots) VAS(vertical air speed in feet/MINUTE)
37.7286 -122.4901 139 6:14:56 PM 11125 256 0
37.6863 -122.4439 139 6:15:50 PM 11100 254 -128
37.6219 -122.3773 144 6:16:54 PM 11100 253 -128
37.5626 -122.3368 152 6:17:52 PM 10225 250 -1152
37.501 -122.2965 152 6:18:52 PM 9150 248 -768
37.4398 -122.2477 120 6:19:56 PM 8800 250 -1024
37.4136 -122.1699 112 6:20:54 PM 7800 249 -1152
37.4211 -122.0942 44 6:21:52 PM 6225 244 -2304
37.4816 -122.0775 327 6:22:54 PM 5050 241 -1408
37.52 -122.1406 297 6:23:52 PM 4275 219 -384
37.5477 -122.2064 297 6:24:54 PM 3400 202 -1024
37.5726 -122.2652 297 6:25:54 PM 2175 186 -1152
37.5954 -122.319 297 6:26:54 PM 1100 149 -1536
37.6123 -122.3595 297 6:27:54 PM 75 113 -384

Those are data with 1-minute resolution. I have not yet converted the lat/long into distance out from threshold, but I want to draw you attention to the final data column, vertical air speed. On a graph it looks like this:



There were 3 pitch/VAS cycles during the final 10 minutes of this flight. To any of you that fly, this WILL NOT indicate a stabilized approach.

However long it takes the engines on the Boeing 777 to drag you out to a missed approach, it was THEN that the pilots should have called it. From FDR audio we now understand that the missed approach call was made at -1.5 seconds, and engine spooling at -8 seconds. Not soon enough.

SFO was CAVU-visibility-clear. The Instrument Landing System (ILS) was off, and that was known to all incoming pilots, including those who performed earlier, successful arrivals that morning. It is not certain whether PAPI lights were available.

Due to the ILS outage, this would have been a ‘visual approach’. In my words this means that the runway should keep the same shape, it just gets bigger. The VAS excursions above suggest (but do not prove) that the pilot flying was chasing some instrument indication, and perhaps not looking out the front window. It will be difficult to know that, ever, regardless of the flight-recorder data.

There is another reference to the incident flight’s ADS-B data in

The Aviationist » [Updated] Asiana Air 214 crash landing analysis: the B777 flew a high, fast and steep approach and almost stalled on final

And it does not match exactly to what I linked above, in the final minutes. I cannot explain this difference. Both suggest that this aircraft was doomed, at least a few minutes out, for not increasing power earlier. The flight data recorder will eventually present much more detailed and accurate information. Also, ADS-B data is apparently supposed to be at 1-second resolution:

Automatic dependent surveillance-broadcast - Wikipedia, the free encyclopedia

Raising the nose will NEVER solve a slow aircraft’s problem, without added thrust. Yet, breaking off the tail may have shed enough energy to save many lives in this incident. Boeing builds a good ship also, let no one dispute that.

We consider what it means to shoot ‘visual’ as opposed to ILS approaches. The latter are almost always done after long oceanic flights and heavily practiced. The former are practiced only according to individual airline’s policy; I know of no ICAO requirement for them.

There are affinity websites suggesting that Korean airline companies in particular do not adequately train pilots for visual approaches. Whether or not that is so, I hope that all airlines will take notice. Everybody has computer simulators; gawd if they didn’t I’d not want to get on their planes! Train pilots for all approaches including visual.

We could continue by looking at why aircraft need to bring some energy to the arrival point, and where that energy goes (wheel contact and rolling resistance, aero drag, brakes, thrust reversers if you’ve got ‘em).

This may be similar to energy balances that Bob Wilson has done for Prius before. However it might not be safe to collect data on a landing roll.

 

This is a great thread! It is certainly one of the best I have read. Here is a very good read on the issue too.

Professional Pilots on the San Francisco Crash - James Fallows - The Atlantic

The 777 can catch you out 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.

If the Asiana was a bit high (quite normal for SFO) then regained the visual glideslope, the rate of descent would have decreased and the speed would have started slowly reducing but with the thrust levers staying at idle the 777 would now be in the same situation as the Turkish 737 at AMS, ie speed decreasing below Vref and not being noticed.

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.

Just a theory but I think it far more likely than engine failure, radalt failure or autothrottle failure and I suspect when the events are unravelled this will be what has happend.
Let's hear from another PPRuNe pilot, on a compounding factor. I won't explain all the references, but essentially he is explaining why many things could have gone wrong at once. "Lining up the holes" alludes to the image of redundant aviation safety measures as a series of slices of Swiss cheese. Each of them has its weak points, or holes -- but if you lay down enough slices, odds are the holes won't all line up and you'll still have some coverage everywhere:
SFO and their notorious ATC instructed 'slam dunk' visual approaches [in which the planes are kept high, then ordered to descend quickly before landing] from downwind have resulted in so many incidents at our airline that it is a regular item in recurent simulator training.

Throw in the lack of visual or electronic glideslope guidance and the holes are lined up. True, you can set up an LNAV/VNAV profile but this requires a bit of heads down time in the box at a busy phase, not easy unless you are expecting the manouvre.
And from another pilot, in response to the "slam dunk" point:
Well said - I couldn't agree more.

I would agree that as a professional pilot we should of course be more than capable of rising to the challenge of such an ATC imposed "slam dunk" approach - however please consider these factors that could all conspire to affect pilot performance

>a long 10 to 12 hour flight
>middle of the night body clock time
>to an airport that you may be not so familiar with (long haul pilot roster - you may only visit the destination once in two or three years)
>a slam dunk procedure that would be a challenge at the best of times (I bet even the short-haul/ domestic colleagues get it "not quite right" on occasions.

For what it's worth - I am of the opinion that slam dunk approaches for "Heavy" jets like the B777 these have no place at a major international airports.

In a "heavy" jet it's always (in my experience) a challenge to "get down & slow down" and become stabilised on this particular approach at SFO - something that sometimes ATC fail to appreciate.

Throw into the mix this runway allegedly not having any functioning ILS or even visual vertical reference guidance system - then it all adds to the possibility of "an accident waiting to happen."
You can find more at the site if you're interested. Finally, I see just now that Patrick Smith has put up his own analysis, which properly stresses (a) the rarity of airline accidents in general, (b) the likelihood that early speculation will turn out to be wrong, (c) the professionalism, bravery, and skill of the cabin crew in getting so many passengers safely off a burning plane, but also (d) this:

 

Beautiful VFR day, and a pilot unfamiliar with the airport. When landing on or over water whatever depth perception and cues you may have are poor and unreliable. Could it be as simple as a mis-set altimeter and the pilot flying looking out the window while relying on an autothrottle that may not have been enabled?

 

...so this scenario is looking correct, right? The NTSB says the flight trainer (co-pilot) had his Flight Director on so the autothrottle would not engage to control. What is the implication if this scenario is correct?

Finish the sentence for me, "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 until too late...." What would 777 pilots think if yes above is found to be the case: Pilot error? or bad control system in the plane? I guess bad communication between pilot and co-pilot is one thought, possibly due to cultural norms.

PS- Question: why does SFO ATC prefer to "slam dunk" planes onto the runway? Noise abatement or other reason?

 

Hello and thanks to Bob Hahn for giving us the perspective from row zero. Indeed there are amazing tales at that PP rumors website.

There may be two important take away lessons here. One I suggested, for all airlines to keep their staff sharp on operations with fewer electronic aids. ILS is not universal worldwide, and it could go down anywhere when you are 10 miles out and staring at the needles. Excellent moment to lift thine eyes and look at the shape of the runway.

Hahn suggested the other, that rapid descents are not easy to recover from if you get below 3 % slope, and harder still in a big bird that takes more than a few seconds to respond to throttles up.

There are airlines that could be bankrupted by the inevitable payouts to come. Don't know Asiana's status. Boeing may get on the hook (lawyers would love to get Boeing on the hook) if those two slides deploying 'indoors' can be show as a design fault. Other than that, that darn airframe held together really well.

 

Forgot to mention that I made a serious error in my first post here. Vertical airspeed is in feet per minute, not feet per second. In fact I'm going to edit that into oblivion right now.

 

The root cause is not going to be simple. Many factors play into this. Pilot may not have been fit for duty, fatigue may come into play. The inexperience of the trainie and lack af attention to him by the trainer and entire crew is huge.
The airport not having glide slope certainly players into it. The list will certainly increase. From the limited understanding of the entire event, the incomplete factual reports and interviews, I think the very bottom line is, for many reasons the pilot and crew were or became distracted to the point they failed to monitor essential parameters. I do not believe it is the reason for this event, obviously humans react to situations to the their very best abilities.
I hope is NTSB does not blame the pilots. It simply would not be accurate or helpful. This crew was very experienced in aviation. They like every single human got caught up in a situation that required action, they simply were making decisions they were positively sure were correct. Yet it still happened. God bless those guys, I'm sure no one would trade places with those soles today.

 

OMG... the NTSB DID tell the news this...

NTSB apologizes for gaffe over derogatory Asiana pilot names - Yahoo! News

 

Is everything "racist" now? It's a F'ing joke, in poor taste, but still a joke.

 

It is sad that there is another child that has perished from this plane running into the ground. From what is being said of the others still in the hospital, there may be a couple more soon... and there will be many that are paralysed from spinal fractures.

 

The airline obviously needs the assistance of the legal firm Dewey, Cheetham & Howe.

 

^ You can say that again, this airline is going to need some damn good lawyering. Even though pilot "Sum Ting Wong." had many hours as a Captain on other aircraft, he was a rookie pilot in the Boeing 777 and Asiana put him there. In the Co-Pilot seat beside "Sum Ting Wong" they put Instructor "Wi To Lo" also a first timer behind the controls of a 777. The other two pilots, "Ho Li Fuk" and "Bang Ding Ow" were about as useful as their names are humorous, They must think the "Round Eye's" are idiots for not "phonetically spelling" out the names before broadcasting them but on the intelligence scale they sure as hell aren't far behind for allowing rookie pilots access to the controls on an unfamilar aircraft with hundreds of souls on board.

 

Everyone has to learn somewhere. All pilots are at one point inexperienced just like all drivers on the road are at one point inexperienced.

Im no pilot but my friends dad pilots a 747 from SFO to a couple Chinese cities all the time. He has given stories of all sorts of things at the SFO airport that keeps you on your toes. An experienced pilot flying for his whole life can still have troubles landing there because of the wind and hard landings on the big planes.

This is a guy that has did 747 landings on runway 13 of Kai Tak when it was open, which any older Hong Kong pilot will attest to being a crazy landing. Wrap around a mountain, some skyscrapers, make a giant turn only 600ft above the water with the only indicator being a checkered billboard on the ground and then land with no second chances. As far as I know, there was no way to use guidance systems on the final approach because the winds of the harbour were pretty chaotic and the landings were all visual at least from the checkboard onwards. Maybe that improved before it was shut down.

Any aircraft accident is a bad accident, but on the scale of plane disasters this was pretty low on the list.

 

I am not a pilot but I am surmising maybe the instructor may have had his settings wrong which prevented the auto speed from keeping speed, and maybe cultural factors make it harder for the trainee to say - hey you got your flight controller set right? Am I remembering correctly the Air France off Brazil also the issue was pilot and co-pilot had different settings and both have to set the same for the plane to respond properly.