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Armchair air crash investigator

momav.me

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Re: Armchair air crash investigator

#21

Post by jared314 »

JshWright wrote: post #9
jared314 wrote: post #6

Thank you for your armchair analysis, but I will wait for the NTSB's report.

That seems needlessly snarky in response to some thoughts that are very clearly labeled as speculation.

It was snarky, and I expected the down votes. But, I think it needs to be said. Neither I, nor the OP, have enough information to make any conclusions. It is just a lot of observations, rumors, and opinions.

I love speculating about everything from government policy to interpersonal relationships. (It helps me validate my mental model of the world.) But, in this case, I know the NTSB currently has a better picture of the situation than anyone on the internet.

Re: Armchair air crash investigator

#23

Post by trothamel »

kop316 wrote: post #13

"The final bit of information is interesting. It shows a positive rate of climb – 120 feet per minute to be exact, which for a jet airliner, is very slow. For reference, at takeoff the vertical speed is most often +1500 feet per minute. Another interesting bit of information is the aircraft’s airspeed; 85 kts – for a Boeing 777 that is (and I’m guessing here) probably way below stall speed." That is actually expected…

I'm not sure we can believe the last data point - it's possible that's a real ascent, or it's possible it's caused by failing hardware as the plane crashes.

Re: Armchair air crash investigator

#24

Post by cjrp »

jervisfm wrote: post #18

It goes without saying that my qualifications in aviation matters are only as an aviation enthusiast and for the full cause of the accident, we'll have to wait for the NTSB report (which has access to vital black box data and cockpit recordings). However, I did give this accident some thought as well given the circumstances of the accident and came the pretty much the same final conclusion as the OP. An airline pilot…

Pilots will actually very rarely use the autoland functionality (apart from when weather, e.g. low visibility, requires it, and also to ensure that they're current with the procedure). They'll use the autopilot for the initial part of the approach, but then when visual with the runway will often disconnect it in order to fly the actual landing manually (still following the indications on the flight director, which are provided by the localiser/glidescope signals).

Re: Armchair air crash investigator

#25

Post by proexploit »

Lusake wrote: post #4

Here is graphical comparison of safe landing and Asiana crash: https://pbs.twimg.com/media/BOhIDCWCUAApHFV.jpg:large . Also it appears that runway was modified: http://metabunk.org/sk/HL7742_777_Crash%2C_Korean_Asiana_Air...

Worth noting that with a modification like that, it looks like it actually gives extra space for landing, not less. So that piece probably isn't a factor at all.

Re: Armchair air crash investigator

#27

Post by vladd »

gklitt wrote: post #11
pcl wrote: post #7

Earlier quoted context omitted.

Interesting. I wonder what the Asiana's descent profile looks like compared to the average and some outliers of other safe 777 landings at SFO. Did you generate that image? If not, what was the source?

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?

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

Re: Armchair air crash investigator

#28

Post by pedrocr »

momavujisic wrote: post #17
madiator wrote: post #12

Sorry to go offtopic here, but the images seem to be used without any credits. The first one was taken by David Eun ( https://path.com/p/1lwrZb )

I'm actually working right now to try to put some kind of overlay over the images for credit situations. My blog is still a WIP. Sorry!

You say that as if giving credit is enough. If you don't have a license/permission to use the image you're violating copyright and the correct response is to take it down.

Re: Armchair air crash investigator

#29

Post by rdl »

NY Daily News is reporting that VASI was down as well (http://www.nydailynews.com/news/national/expert-runway-guida...) Which appears to be due to someone incorrectly reading a post-crash NOTAM which is about the aids being gone due to the crash, so there's no particular reason to think VASI was down before the crash.

I really don't think I'd trust SF city government to run an airport, even under FAA regulations. Look at every other city service SF has, and imagine that quality applied to preventing hundred ton soda cans full of people and jet fuel from exploding.

Re: Armchair air crash investigator

#30

Post by simpleigh »

cjrp wrote: post #24
jervisfm wrote: post #18

It goes without saying that my qualifications in aviation matters are only as an aviation enthusiast and for the full cause of the accident, we'll have to wait for the NTSB report (which has access to vital black box data and cockpit recordings). However, I did give this accident some thought as well given the circumstances of the accident and came the pretty much the same final conclusion as the OP. An airline pilot…

Pilots will actually very rarely use the autoland functionality (apart from when weather, e.g. low visibility, requires it, and also to ensure that they're current with the procedure). They'll use the autopilot for the initial part of the approach, but then when visual with the runway will often disconnect it in order to fly the actual landing manually (still following the indications on the flight director, which ar…

Relevant link: http://www.freakonomics.com/2011/12/12/cockpit-confidential-...

"The touchdown had been a fully manual one, as the vast majority of touchdowns are."

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