Boeing 777 Crashes in San Francisco

Lingua Franca · 08-07-2013 12:44AM

NuckingFacker wrote: »

Yeah, but it took a loong time to get sorted and I don't remember them grounding the fleet.

I'm sorry, I thought you said that it would cost too much to put right and gave rudder jam as your example of a problem that cost too much to put right.

I was responding to a scaremongering nonsense post. You could have agreed with them instead.

You didn't mention the cabling bit..

Because when I googled it, it turned out to be standard practice.

Anyway, my grandfather was an aircraft fitter and had no problem with flying. My fiance is in aviation, as of course are his colleagues and friends, and they have no problem with flying. I'm just a frequent flyer but I have no fears either.

bnt · 08-07-2013 01:13AM

marialouise wrote: »

...
Target speed for the approach was 137 knots.
...

On another forum, someone posted data recorded by an ADS-B system -the data used by flight tracking sites such as FlightRadar24:

LAT|LONG|HDG|UTC|ALT|GS|VS
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

emphasis added: at 75ft AGL, they were (barely) flying at 113 knots . :eek:

More analysis here, with graphs comparing this to other flights. The NTSB briefing seems to back the low speed theory.

08-07-2013 01:16AM

I have no idea what any of that means ?

Peregrine · 08-07-2013 01:57AM

bnt wrote: »

LAT|LONG|HDG|UTC|ALT|GS|VS
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

Thanks for that

Yeah the speed and altitude is..concerning.

The aircraft was a bit too high til about 4 miles(nautical) out and then it suddenly descended quicker to compensate maybe. 113 knots at 75ft and even lower at touchdown is way too low :eek:

The video has 'stall' written all over it..

bnt · 08-07-2013 11:03AM

Note that the data above is from GPS, so the speed is ground speed, not air speed. The wind at the time was approx. 7 knots @ 210, so airspeed would be 4-6 knots higher. But even if it was around 120 knots, that's still way too low.

PS: these days, most aircraft constantly broadcast their position, speed & heading over radio, using a standard called ADS-B. It's useful for reasons that are fairly obvious, I hope e.g. collision avoidance. You can pick this up on amateur radio, and even set up a feed to sites like FlightRadar24, which show flights on a map in close to real time. Right this minute, for example, I can see three Virgin Express flights - from New York, Chicago and Las Vegas - about to land at SFO a few minutes apart, while a Korean Airlines flight is about to take off for Seoul.

Capt'n Midnight · 08-07-2013 12:16PM

Strawberry Milkshake wrote: »

I have no idea what any of that means ?

The GS (Ground Speed) figure should have been about 137.

For whatever reason the plane wasn't going fast enough for controlled flight.

You can try to get extra lift by tilting the plane back, it works to a point, because doing that also slows the plane down which of course means you loose lift (in films that's when you get the stick shaking and all the warnings)

A visual analogy (incorrect but easier to visualise), if you look at water eddies trailing from a bridge you will see that vortexes (little whirlpools) and when the water flows faster they are shed alternatively from left and right. When you are flying a plane normally you have a nice stable vortex, when you stall it's shed and down you go, unless you have enough vertical height to be able to noise dive the plane so that the air over the wings is fast enough to get enough lift that you can recover from the dive.

NuckingFacker · 08-07-2013 07:14PM

Are the reports that the pilot had 43 hours flying time on 777s and zero landing experience on them confirmed yet? Seems a too low airspeed leading to a stall is the official version now - makes sense.

bnt · 08-07-2013 07:31PM

Confirmed, but I think it's a red herring. He has thousands of hours piloting a Boeing 747, and was being supervised by a senior 777 pilot. Every pilot is a "newbie" at some point, that's what training regimes are for. But I do suspect some problem with crew resource management is involved.

neaideabh · 08-07-2013 09:58PM

bnt wrote: »

Confirmed, but I think it's a red herring. He has thousands of hours piloting a Boeing 747, and was being supervised by a senior 777 pilot. Every pilot is a "newbie" at some point, that's what training regimes are for. But I do suspect some problem with crew resource management is involved.

Could there be a chance that the flight suffered the same prob as that from the BA Boeing 777 that crashed landed at Heathrow? The fuel freezing in the lines and blocking them!

bnt · 08-07-2013 10:11PM

Unlikely. Passengers didn't report any engine problems, and the pilots did throttle up seconds before impact (story). There's also the fact that the pilots said nothing on the radio before the crash, only afterwards.

neaideabh · 08-07-2013 10:20PM

bnt wrote: »

Unlikely. Passengers didn't report any engine problems, and the pilots did throttle up seconds before impact (story). There's also the fact that the pilots said nothing on the radio before the crash, only afterwards.

Yeah... but didn't think BA flight not respond to throttle, but it was found through the investigation to be a minor problem that can be fixed by giving a quick burst of throttle to force the ice through the lines. Maybe, this flight lost power due to an ice blockage and despite being briefed on the recommended actions for unresponsive engines post BA crash, didn't carry out the action and by the time the engines did respond, it was too late!

Capt'n Midnight · 08-07-2013 11:23PM

www.boeing.com/assets/pdf/commercial/airports/faqs/arcandapproachspeeds.pdf

None of the Boeings have approach speeds that low so wouldn't matter which type of plane the pilots were used too.

(on the list DC3/4 are old propeller driven planes)

galwayjohn89 · 08-07-2013 11:33PM

neaideabh wrote: »

Could there be a chance that the flight suffered the same prob as that from the BA Boeing 777 that crashed landed at Heathrow? The fuel freezing in the lines and blocking them!

Very unlikely, all affected engines were fixed and this 777 had different engines and engines were at very high speed at impact.

King George VI · 09-07-2013 01:19AM

I just heard on Sky News that one girl that did survive the crash is believed to have been hit and killed by a fire engine that was on it's way to the crash. That's rough.

bnt · 09-07-2013 02:30PM

They know one girl was run over, but they don't yet know whether she was alive when it happened.

There's a good summary of the issues and the current understanding of the situation on Autopia. I don't know whether the "slam dunk approach" has been mentioned on this thread, or whether the ATC at SFO actually requested that for this flight, but it appears that they made a visual approach, not an ATC-guided approach.

But regardless of that, or the ILS availability, or anything else: airspeed is the #1 critical factor in making a successful landing, and getting it that badly wrong it is unacceptable and a Very Bad Thing:

The 777 impacted the ground at 106 knots — 122 mph — and at least several hundred feet shy of the runway touchdown zone.

:eek: again

Boeing 777 Crashes in San Francisco

Comments