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How would an Airbus have reacted in SFO crash?  
User currently offlineeaa3 From United States of America, joined Sep 2007, 1028 posts, RR: 0
Posted (1 year 4 months 3 weeks 20 hours ago) and read 11477 times:

I realize that this is a question without an answer and I'm not advocating Airbus above Boeing. I'm just wondering how the different flight envelope protection systems would have reacted on Boeing and Airbus aircraft.

We know that the crashed Asiana B777 at SFO was very close to stall speed on final. Given that Airbus aircraft have a different flight envelope protection system that doesn't allow the aircraft to be stalled would an Airbus aircraft have reacted differently to the mistakes that the pilot made on the Asiana B777 at SFO and maintained a higher speed on final.

How slow would the Airbus flight envelope protection system have allowed the aircraft to get on final or is there no difference up until the aircraft stalls.

50 replies: All unread, showing first 25:
 
User currently offlineKarelXWB From Netherlands, joined Jul 2012, 12699 posts, RR: 35
Reply 1, posted (1 year 4 months 3 weeks 19 hours ago) and read 11393 times:

I don't think anyone can give you a real answer to this. The pilots of the Tripoli A330 crash were able to crash their jet during final approach so it is not impossible to do despite the flight envelope protections.

Quoting eaa3 (Thread starter):
up until the aircraft stalls

During cruise, the stall warning will trigger even before the plane actually stalls but it looks like the warning is different in landing configuration.



Only two things are infinite, the universe and human stupidity. And I'm not sure about the universe.
User currently offlinePHX787 From Japan, joined Mar 2012, 7859 posts, RR: 19
Reply 2, posted (1 year 4 months 3 weeks 19 hours ago) and read 11252 times:

I don't like the wording of this question at all. I'm not an av expert but I mean, if this was pilot error regarding the air speed, then any plane would have had such an accident.


我思うゆえに我あり。(Jap. 'I think, therefore I am.')
User currently offlineIndianicWorld From Australia, joined Jun 2001, 3010 posts, RR: 0
Reply 3, posted (1 year 4 months 3 weeks 19 hours ago) and read 11223 times:

Quoting PHX787 (Reply 2):
if this was pilot error regarding the air speed, then any plane would have had such an accident.

I agree. No airplane is foolproof unfortunately.


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5913 posts, RR: 11
Reply 4, posted (1 year 4 months 3 weeks 19 hours ago) and read 11225 times:

I'm of the opinion that this is NOT a question "without an answer."
The answer is: yes, if the pilots of an Airbus allowed the aircraft speed to deteriorate that closely to the ground, the plane would have crashed.
There's precedent for an Airbus crashing by landing where a runway wasn't, mind you.... waaaaay back in the day. Granted, those were different conditions, but these guys yesterday didn't have time to execute corrective action before they hit.

We like to think that increased automation prevents bad things from happening, and in some cases, it does. But, just as with AF447, which was completely pilot error, the laws are the laws: if you fly a plane into the ground, it will crash.


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3425 posts, RR: 4
Reply 5, posted (1 year 4 months 3 weeks 19 hours ago) and read 11222 times:

Yes, no computer can negate the laws of physics. You get ANYTHING low, slow, and idle power like this and its done.

The famous A320 that played lumberjack in the woods instead of flying is a well known example of energy management being important.


User currently offlineAF185 From Hong Kong, joined Sep 2012, 262 posts, RR: 0
Reply 6, posted (1 year 4 months 3 weeks 19 hours ago) and read 11109 times:

Quoting XT6Wagon (Reply 5):
The famous A320 that played lumberjack in the woods instead of flying

OK, I did laugh to that one 


User currently offlinegarpd From UK - Scotland, joined Aug 2005, 2696 posts, RR: 4
Reply 7, posted (1 year 4 months 3 weeks 19 hours ago) and read 11086 times:

After several Airbus crashes where the pilots got it too low and/or too slow (A300, A310, A320, A330), I would have thought this question to be entirely irrelevant.
No plane is fool proof. A bad pilot will crash a plane regardless what protections are it place as it is the pilot (contrary to popular belief) that is ultimately in control.


A v B pissing match in ...3......2.......1......



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User currently offlineAirbusA370 From Germany, joined Dec 2008, 253 posts, RR: 0
Reply 8, posted (1 year 4 months 3 weeks 19 hours ago) and read 11086 times:

Quoting XT6Wagon (Reply 5):

Exactly. This is similar to the Habsheim A320 crash. Too low, too slow and engines spool up to slow...


User currently offlineseahawk From Germany, joined May 2005, 1229 posts, RR: 0
Reply 9, posted (1 year 4 months 3 weeks 19 hours ago) and read 10781 times:

Engines at idle, low and slow - the Airbus engines would not spool up any faster.

User currently offlinebongodog1964 From United Kingdom, joined Oct 2006, 3658 posts, RR: 3
Reply 10, posted (1 year 4 months 3 weeks 19 hours ago) and read 10715 times:

In a way protection systems have an adverse effect, people trust and rely on them to the point where the systems cannot cope with the users incompetence. If a pilot can crash a seemingly fully functional 777, I'm sure the protection systems on an A330 wouldn't help either.

User currently offlinemoo From Falkland Islands, joined May 2007, 4061 posts, RR: 4
Reply 11, posted (1 year 4 months 3 weeks 19 hours ago) and read 10686 times:

Why were the engines at idle? I always thought that you had a decent amount of power selected precisely because it takes the engines so long to spool back up - you controlled the speed using other aerodynamic devices during approach, but kept the power on incase you do infact need it at a moments notice.

User currently offlinegarpd From UK - Scotland, joined Aug 2005, 2696 posts, RR: 4
Reply 12, posted (1 year 4 months 3 weeks 19 hours ago) and read 10585 times:

Quoting moo (Reply 11):
Why were the engines at idle?

Some would say pilot error. But despite the facts being there, apparently it's too soon to say that.

I know what I believe.



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User currently offlineQatarA340 From Qatar, joined May 2006, 1880 posts, RR: 10
Reply 13, posted (1 year 4 months 3 weeks 18 hours ago) and read 10447 times:

I dont get why planes dont have some sort of sensor to know that the plane is actually TOO low and they have to abort landing. Each plane should have the elevation of the runway, and their own elevation and the geographical coordinates of the runway and then they could tell if the airplane is actually too far, too low, too close to the runway threshold.


لا اله الا الله محمد رسول الله
User currently offlineeaa3 From United States of America, joined Sep 2007, 1028 posts, RR: 0
Reply 14, posted (1 year 4 months 3 weeks 18 hours ago) and read 10289 times:

I realize that you can crash an Airbus plane just as any other. The crash in the forest was, if I remember correctly, because the plane entered flare mode.

However, my question is the following: What would the flight envelope protection system on an Airbus have done if the aircraft slowed down as much as was the case here.


User currently offlineoly720man From United Kingdom, joined May 2004, 6840 posts, RR: 11
Reply 15, posted (1 year 4 months 3 weeks 18 hours ago) and read 10275 times:

Quoting QatarA340 (Reply 13):

There are enough sensors on an aircraft to say where it is and the crew should be aware of that. And there is the GPWS that will shout "terrain" at the crew if the plane is too low, e.g.

http://www51.honeywell.com/aero/Prod.../Egpws-Home3/Products4/Mark-V.html

but I would expect that wouldn't be turned on for a landing over the sea, because there wouldn't, ideally, be any ground to be worrying about since the crew could see what they were doing and where they were going.

Having the sensors is one thing, but it would appear that the crew got the plane into a flight situation it couldn't get out of (too low, too slow after being too high, too fast. Allegedly) and all the sensors in the world won't solve that.



wheat and dairy can screw up your brain
User currently offlineKarelXWB From Netherlands, joined Jul 2012, 12699 posts, RR: 35
Reply 16, posted (1 year 4 months 3 weeks 18 hours ago) and read 10209 times:

Quoting oly720man (Reply 15):
There are enough sensors on an aircraft to say where it is and the crew should be aware of that. And there is the GPWS that will shout "terrain" at the crew if the plane is too low, e.g.

Correct me if I'm wrong, but I thought the GPWS does not work with the landing gear down and flaps deployed.

[Edited 2013-07-08 03:14:38]


Only two things are infinite, the universe and human stupidity. And I'm not sure about the universe.
User currently offlinebongodog1964 From United Kingdom, joined Oct 2006, 3658 posts, RR: 3
Reply 17, posted (1 year 4 months 3 weeks 18 hours ago) and read 10187 times:

There is a train of thought which suggests that the flightcrews biggest problem was that the unavailability of the ILS left them with a manual approach which they failed to cope with. To me the answer isn't flight protection systems or any other technology. If they can't balance airspeed, engine power and the sink rate satisfactorily on a calm sunny day with good visibility, they probably can't handle the advice given by any warning system. Look at how the crew of AF447 managed to ignore all the Airbus technology, they couldn't even work out that the best way out of a stall is to dive rather than pull up sharply.

User currently offlinescbriml From United Kingdom, joined Jul 2003, 12801 posts, RR: 46
Reply 18, posted (1 year 4 months 3 weeks 18 hours ago) and read 9945 times:
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Quoting bongodog1964 (Reply 17):
Look at how the crew of AF447 managed to ignore all the Airbus technology, they couldn't even work out that the best way out of a stall is to dive rather than pull up sharply.

Mainly because they totally failed to follow SOP when they lost airspeed indication and then showed appalling lack of airman-ship in not recognising and dealing correctly with a stall.



Time flies like an arrow, but fruit flies like a banana! #44cHAMpion
User currently offlineairbazar From United States of America, joined Sep 2003, 8576 posts, RR: 10
Reply 19, posted (1 year 4 months 3 weeks 17 hours ago) and read 9761 times:

Quoting AA737-823 (Reply 4):
We like to think that increased automation prevents bad things from happening, and in some cases, it does. But, just as with AF447, which was completely pilot error, the laws are the laws: if you fly a plane into the ground, it will crash.

Well, but automation would not fly the plane too low, or too slow in the first place. It's humans overriding automation that tends to cause problems   Time to get rid of the pilots  I'm kidding of course but if this was an ILS approach, my suspicion is that there would have been no crash.

Quoting QatarA340 (Reply 13):
I dont get why planes dont have some sort of sensor to know that the plane is actually TOO low and they have to abort landing.

They do, but you're landing so you ignore the "too low, pull up" warnings  


User currently offlineC680 From United States of America, joined Apr 2005, 588 posts, RR: 0
Reply 20, posted (1 year 4 months 3 weeks 17 hours ago) and read 9710 times:

Quoting moo (Reply 11):
Why were the engines at idle?

An excellent question for the flight crew of OZ 214. I'm sure the NTSB will have that question on their list.

Quoting moo (Reply 11):
I always thought that you had a decent amount of power selected precisely because it takes the engines so long to spool back up - you controlled the speed using other aerodynamic devices during approach, but kept the power on incase you do infact need it at a moments notice.

You are correct.

A key comment from the NTSB briefing "a few seconds before impact, the throttles were advanced and the engines reacted normally" so the throttles worked, the engines worked, all that remains in question is the human who is responsible for the position of the throttle (either by monitoring automation or manipulating the throttle by hand.)

An Airbus would have reacted exactly the same as a Boeing or a Cessna.

Think about it. How does a plane land? Power back to idle, Flare (below "target speed" or Vref) and wheels make contact with the runway. That's exactly what happened here if you substitute the words "sea wall" for "runway" None of Airbus systems prevent a plane for landing in the wrong spot.

[Edited 2013-07-08 04:04:22]


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User currently offlineoly720man From United Kingdom, joined May 2004, 6840 posts, RR: 11
Reply 21, posted (1 year 4 months 3 weeks 17 hours ago) and read 9657 times:

Quoting KarelXWB (Reply 16):
Correct me if I'm wrong, but I thought the GPWS does not work with the landing gear down and flaps deployed.

I'd expect it will depend on the system. It may make sense to not have it operational with the gear down, but there may be situations where the aircraft is not landing and the gear is down (hydraulic failure, or failure to retract) and the system is live. It may be a manual intervention to turn it off rather than have it automatically turn off when in a landing configuration, for example.



wheat and dairy can screw up your brain
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17115 posts, RR: 66
Reply 22, posted (1 year 4 months 3 weeks 17 hours ago) and read 9455 times:

Quoting QatarA340 (Reply 13):
I dont get why planes dont have some sort of sensor to know that the plane is actually TOO low and they have to abort landing. Each plane should have the elevation of the runway, and their own elevation and the geographical coordinates of the runway and then they could tell if the airplane is actually too far, too low, too close to the runway threshold.

They sorta do in parts of EGPWS. However this sort of sensing is very very hard to design without getting zillions of spurious results. Enhanced GPS systems that can really give the needed data are pretty bleeding edge AFAIK.

[Edited 2013-07-08 05:08:40]


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17115 posts, RR: 66
Reply 23, posted (1 year 4 months 3 weeks 16 hours ago) and read 8598 times:

Quoting eaa3 (Reply 14):

I realize that you can crash an Airbus plane just as any other. The crash in the forest was, if I remember correctly, because the plane entered flare mode.

Flare mode had nothing to do with the crash. It happened because the pilot had let the airspeed and altitude decay while at flight idle at a very low altitude. No way the power available was going to make that plane climb again in the vertical distance available.

The envelope protection system kept the wings nicely level while avoiding the stall, probably saving many lives.

There were many contributing errors, such as a last minute change of runway, demonstration flying below legal altitude, demonstration flying with passengers on board, lack of briefing, "watch this" attitude.

Quoting eaa3 (Reply 14):
However, my question is the following: What would the flight envelope protection system on an Airbus have done if the aircraft slowed down as much as was the case here.

AFAIK it would have kept increasing angle of attack until the wing was just below the critical angle of attack, then increased thrust.

Quoting KarelXWB (Reply 16):
Correct me if I'm wrong, but I thought the GPWS does not work with the landing gear down and flaps deployed.

You'd get a "glideslope" warning but only if you were following an ILS.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBoeing77w From United Kingdom, joined May 2007, 209 posts, RR: 0
Reply 24, posted (1 year 4 months 3 weeks 16 hours ago) and read 8579 times:

Quoting QatarA340 (Reply 13):

EGPWS systems use a database of airfields to know when an aircraft is on an approach to a runway. Mode 4 provides warnings of "Too Low Gear" "Too Low Flaps" and "Too Low Terrain". These alerts are triggered by certain conditions which ultimately prevent an aircraft from making an approach incorrectly configured.

There is also a "SINKRATE" warning as a part of EGPWS Mode 1 which alerts crew to excessive rates of descent and is activated prior to a "PULL UP" warning. Below 1000ft any descent rate in excess of approximately 2000ft per minute will activate the warning.

There is also a glide slope call which alerts crew to excessive deviation below the GS on approach. Obviously this is only operational on an ILS approach though.

Quoting oly720man (Reply 15):
but I would expect that wouldn't be turned on for a landing over the sea

The systems are always active in normal operations. If a non-normal situation occurs then procedures can direct crew to disable certain aspects of the system to prevent spurious warnings

The warning systems are there.

Quoting moo (Reply 11):
Why were the engines at idle?

Depending on circumstances it may necessary to significantly reduce thrust, even to idle, however this is usually only really needed in the later stages of the approach. If the airspeed starts increasing significantly when the aircraft is in the landing configuration then the only way to reduce speed is to reduce thrust. Sudden changes in headwinds/tailwinds can dictate this in order to maintain the approach speed. The 5.5 glide slope into London City is obviously fairly 'non standard' but I know of guys who have had to reduce thrust to idle as high as 80-100ft and maintain this until touchdown.

At the appropriate time FADEC will place the engines into Approach Idle. This means a higher N1 and N2 for the same airspeed and altitude compared to Flight Idle (cruise), as a result engine spool up times are reduced and provides quicker acceleration in the event of thrust application/go around.


25 rfields5421 : A summary of my response to the OP which was deleted when the thread was moved. Short answer - the B777 remained largely in one large piece because th
26 Klaus : The question may in fact be somewhat relevant how the Boeing and Airbus autothrottle / autothrust systems work in a manual approach such as this one.
27 77West : I would rather put this here than in the general thread on OZ214, I loaded up this situation in a 737 simulator (biggest I have access too) and let th
28 zeke : The main difference with the Airbus would have been two fold, GS mini looking at the actual wind where the aircraft is compared to the tower reported
29 vikkyvik : Suppose that depends on the flight mode, no? I'm remembering the Indian Airlines 605 crash in Bangalore, where the aircraft was in Open/Idle Descent
30 roseflyer : Honest question. With the autopilot disconnected, what would the envelope protections have done? Does the A330 automatically kick the auto throttle ba
31 Starlionblue : Prevented a stall. Look at the famous 320 crash at Mulhouse. Rock steady right to the ground. "SPEED, SPEED, SPEED" warning as mentioned above. I thi
32 PPVRA : I've seen reports of an unusually steep approach. If you're coming in steep you need to reduce throttle as necessary otherwise you get too fast. This
33 zeke : They would have got the low speed warning "SPEED" a couple hundred feet up, it would have gone off at around Vref-4 kts given the flight path angle t
34 eaa3 : That's very interesting. It suggests that the Airbus flight envelope protection system would not have let them get anywhere close to this slow and it
35 roseflyer : That is not necessarily true. The 777 has the same automatic speed mode protection built into the autothrottles as Airbus does if I understand correc
36 Klaus : A slow decay of airspeed right down to stall speed without any countermeasures kicking in? I have a hard time believing that normal or flare laws on
37 zeke : Not sure about that, it is 400' for one of them on the 777. The 777 as far as I am aware does not have the trajectory computation to know to call "SP
38 mandala499 : We do not know if autothrust was on, off but armed, or unarmed. If it was on, then this shouldn't have happened on an Airbus or a Boeing unless prece
39 Post contains links Klaus : Thank you for your input. According to today's NTSB briefing (as far as I've caught most of the live run – I'm yet to re-watch the recording from t
40 Post contains links Klaus : Further information from the NTSB press briefing: http://www.c-span.org/Events/NTSB-Br...a-Airline-Plane-Crash/10737440372/ Further post-crash cockpit
41 zeke : I said in the CivAv thread, Airbus recommends either both FD on or off, one on, one off is asking for trouble.
42 Klaus : Yes, thank you. But why are there even two separate units, then, if it isn't for sheer redundancy?
43 Post contains images mandala499 : For the Boeings, A/T in the flare would, retard at 27' RA (at least on 737s). For the Airbus FBW, A/T would maintain speed (Selected, or Managed), un
44 zeke : On the airbus they are driven by the associated fmc/ap. in the case of a fm failure, both fds are driven from the same source. I assume the 777 would
45 Max Q : Tragic, tragic, tragic, there is a real cultural issue here. It's incomprehensible to the Western mind that Professional Pilots of this experience cou
46 rfields5421 : I would disagree with some of your statement. I believe the lack of speed issue was a gradually increasing situation. The lower they got the more unl
47 zeke : The record for KE and OZ is not that bad, especially in the last 20 years. My reading of the OZ 744F crash as a result of a cargo fire two years ago
48 PPVRA : Do we know what aircraft the PF was flying just prior to being trained on the 777? If it was the A320, I wonder if he could have mixed up Airbus and B
49 Klaus : Yes, it was the A320 for several years according to the preliminary NTSB information.
50 zeke : I should add while hand flying pilots ignore the flight directors and get low and slow, at around 7 kts below their target speed (130 kts in this cas
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