How safe is (airbus) fly by wire? Airbus A330/340 and A320 family emergency AD
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Originally Posted by Clandestino
Autopilot is pilot's helper
If Airbus could once for all acknowledge this, they would nicely integrate somewhere in the instruments panel that single guarded switch the pilot could sensibly push to allow him to regain control in the shortest time when protections go wild.
Last edited by CONF iture; 1st Jan 2013 at 14:28.
DW
Yes I follow - but I'm not going to presume until the intent is confirmed one way or the other. "Stable flightpath" pitch command or no, if you have positive pitch and select TOGA then the aircraft will climb.
Yes I follow - but I'm not going to presume until the intent is confirmed one way or the other. "Stable flightpath" pitch command or no, if you have positive pitch and select TOGA then the aircraft will climb.
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Mark my words, it will come out that you can't ground an Airbus enough to with stand a direct 100,000 volt lighting strike and not fry something.
Air France went down because those guys lost situational awareness at night in the soup. They didn't know if up was up, down was down, if the plane had air going over the wings or not because the screen weren't given them the information. The CVR conversation confirms this. Three guys looking at the panels and none of them knew what to make of it.
Carry on.
Air France went down because those guys lost situational awareness at night in the soup. They didn't know if up was up, down was down, if the plane had air going over the wings or not because the screen weren't given them the information. The CVR conversation confirms this. Three guys looking at the panels and none of them knew what to make of it.
Carry on.
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No it didn't work and never will. Toga is for go around. Everybody knows that. If you can not hand fly because the autopilot clicks off and you are at night in a bit of turbulence maybe you should try another profession.
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If you have positive Pitch and leave the throttles alone, you may climb. If you leave thrust alone and increase Pitch you will Stall. Increasing Pitch and Throttle sounds like a plan. At least until you Stall. Thirty seconds to sort a touchy roll, fifteen seconds left to live...
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I don't think either of these guys had a clue what they were doing. Sad that airliners hire people with so low qualifications that they can not hand fly. It didn't happen when I was flying.
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bubbers44
I have always respected your feeling about the 447. So what can we take away from the UAS/UAoA related to safety?
Let's ask the pilots who fly them... In fact, let us read what a complete legacy group have to say, and Demand.
From UAS, NO HAL 'LITE' not even HAL 'MINUS', straight to DIRECT.
They don't get alot of time in ALT 2 (b). SO this group says change the cockpit, make it safer.
AOA INDICATION in the Cockpit, safer, important information, SAFER...
CONNECT the SIDESTICKS... Especially in an emergency, it would be nice to know what is commanded....ya think? Make it safer.
With corrupt AOA, Eliminate the need to trash the airspeed system to gain control, make DIRECT plentiful, and easy.
AIRBUS is not going to start building Boeings,bubbers, but some body in Toulouse needs to get their spanners and voltmeters together and get busy.
I have always respected your feeling about the 447. So what can we take away from the UAS/UAoA related to safety?
Let's ask the pilots who fly them... In fact, let us read what a complete legacy group have to say, and Demand.
From UAS, NO HAL 'LITE' not even HAL 'MINUS', straight to DIRECT.
They don't get alot of time in ALT 2 (b). SO this group says change the cockpit, make it safer.
AOA INDICATION in the Cockpit, safer, important information, SAFER...
CONNECT the SIDESTICKS... Especially in an emergency, it would be nice to know what is commanded....ya think? Make it safer.
With corrupt AOA, Eliminate the need to trash the airspeed system to gain control, make DIRECT plentiful, and easy.
AIRBUS is not going to start building Boeings,bubbers, but some body in Toulouse needs to get their spanners and voltmeters together and get busy.
Last edited by Lyman; 31st Dec 2012 at 23:02.
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@CONF iture:
In clean configuration VLS = 1.23 Vs1g, AoA approx. 8.5 degrees.
So yes, when taking off on a cold day it is possible to hit alpha-floor at M<0.53.
Alpha_SW > alpha_max? No.
P.S.
On further thought, the AoA sensors could be frozen in any position when taking off at sub-zero temperatures.
In clean configuration VLS = 1.23 Vs1g, AoA approx. 8.5 degrees.
So yes, when taking off on a cold day it is possible to hit alpha-floor at M<0.53.
Alpha_SW > alpha_max? No.
P.S.
On further thought, the AoA sensors could be frozen in any position when taking off at sub-zero temperatures.
Last edited by HazelNuts39; 31st Dec 2012 at 23:38. Reason: P.S.
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Chris,
First, the question was "How safe is (airbus) fbw?" so we are talking about the aircraft, not the procedures that bolt on to it, just the aircraft.
I am talking about a fully servicable aircraft, I agree with your summary above of a quietly executed manual G/A, I am, for the purposes of this argument, not interested in Direct Law.
My central point is that a conventional aircraft (ie. not fbw, could be an Airbus 300!) with underwing engines will pitch up when TOGA is applied. Since we are going around this is what we want the aircraft to do! So if the pilot does nothing more than push the thrust levers to TOGA the aircraft will go up!
If the pilot of an airbus FBW does nothing more than push the thrust levers to TOGA then the aircraft will accelerate into the ground. Please DO NOT say that this cannot happen, I am relatively inexperienced at this game, still learning after 36 years at it, and I KNOW that if it can be done then it probably will/has been done!
I have time on 737, 744 and Airbus FBW along with others and have no particular axe to grind in favour of any manufacturer, there are simply certain aspects of Airbus design that I feel are fundamentally flawed, the above example being just one of them.
In Normal Law, the A320 pilot simply eases the stick back to achieve the desired pitch change. That is, he/she initiates and controls the pitch attitude, which is intuitive. Later, as the pilot lowers the pitch and the flaps are progressively retracted, the autotrim will respond to keep the elevator close to neutral, and stick movements will be minimal.
I am talking about a fully servicable aircraft, I agree with your summary above of a quietly executed manual G/A, I am, for the purposes of this argument, not interested in Direct Law.
My central point is that a conventional aircraft (ie. not fbw, could be an Airbus 300!) with underwing engines will pitch up when TOGA is applied. Since we are going around this is what we want the aircraft to do! So if the pilot does nothing more than push the thrust levers to TOGA the aircraft will go up!
If the pilot of an airbus FBW does nothing more than push the thrust levers to TOGA then the aircraft will accelerate into the ground. Please DO NOT say that this cannot happen, I am relatively inexperienced at this game, still learning after 36 years at it, and I KNOW that if it can be done then it probably will/has been done!
I have time on 737, 744 and Airbus FBW along with others and have no particular axe to grind in favour of any manufacturer, there are simply certain aspects of Airbus design that I feel are fundamentally flawed, the above example being just one of them.
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Bengerman,
If the pilot of a 737 does exactly the same, then he may stall due to the pitch power couple.
http://www.aaib.gov.uk/cms_resources...OF%2006-09.pdf
"The Boeing 737-300 was on approach to Bournemouth Airport following a routine passenger flight from Faro, Portugal. Early in the ILS approach the auto-throttle disengaged with the thrust levers in the idle thrust position. The disengagement was neither commanded nor recognised by the crew and the thrust levers remained at idle throughout the approach. Because the aircraft was fully configured for landing, the air speed decayed rapidly to a value below that appropriate for the approach. The commander took control and initiated a go-around. During the go-around the aircraft pitched up excessively; flight crew attempts to reduce the aircraft’s pitch were largely ineffective. The aircraft reached a maximum pitch of 44º nose-up and the indicated airspeed reduced to 82 kt. The flight crew, however, were able to recover control of the aircraft and complete a subsequent approach and landing at Bournemouth without further incident."
Would you agree that both crews need to control the pitch attitude?
If the pilot of an airbus FBW does nothing more than push the thrust levers to TOGA then the aircraft will accelerate into the ground.
http://www.aaib.gov.uk/cms_resources...OF%2006-09.pdf
"The Boeing 737-300 was on approach to Bournemouth Airport following a routine passenger flight from Faro, Portugal. Early in the ILS approach the auto-throttle disengaged with the thrust levers in the idle thrust position. The disengagement was neither commanded nor recognised by the crew and the thrust levers remained at idle throughout the approach. Because the aircraft was fully configured for landing, the air speed decayed rapidly to a value below that appropriate for the approach. The commander took control and initiated a go-around. During the go-around the aircraft pitched up excessively; flight crew attempts to reduce the aircraft’s pitch were largely ineffective. The aircraft reached a maximum pitch of 44º nose-up and the indicated airspeed reduced to 82 kt. The flight crew, however, were able to recover control of the aircraft and complete a subsequent approach and landing at Bournemouth without further incident."
Would you agree that both crews need to control the pitch attitude?
Last edited by rudderrudderrat; 1st Jan 2013 at 15:31.
Per Ardua ad Astraeus
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Question for the AB experts. If you are on approach and decide to whack on TOGA, while continuing the approach with no demanded change in pitch (yes, I know....), can the elevator/auto-trim cope to prevent a pitch up?
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If no one is noticing, we are firmly mired in the salient issues re: AF447.
That is a good thing...imo
BOAC, why would one select TOGA and try to maintain an approach?
Yet that is what AB does, failing input of NU?
The Boeing responds consistent with an intuitive design. Thrust=Altitude.
AB is counterintuitive? Neither Intuitive OR Counterintuitive? AB being AB?
If AB was human, "What a 'character' "
That is a good thing...imo
BOAC, why would one select TOGA and try to maintain an approach?
Yet that is what AB does, failing input of NU?
The Boeing responds consistent with an intuitive design. Thrust=Altitude.
AB is counterintuitive? Neither Intuitive OR Counterintuitive? AB being AB?
If AB was human, "What a 'character' "
Last edited by Lyman; 1st Jan 2013 at 15:52.
DozyWannabe
The subject we were discussing at the time was not AF447, it was how the aircraft behaves on approach when there is a need to go around.
The subject we were discussing at the time was not AF447, it was how the aircraft behaves on approach when there is a need to go around.
DozyWannabe "Stable flightpath" pitch command or no, if you have positive pitch and select TOGA then the aircraft will climb.
And to be even more nitpicking, if a go around at slow speed is performed a initial pitch of 1 degree, which per definition is a positive pitch, will not lead to a climb in an FBW airbus in normal Law. You have to have at least a pitch, which assures a positive climb rate. I think it is important, because your answer in response to the question Bengerman is therefore quite unprecise and misleading. The connection to AF447 is, because they have been mislead by a similar wrong assumption.
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Good heavens, what a fruitless discussion.
If you perform a manual G/A you have a target thrust and a target pitch attitude to achieve, and a target speed to maintain. TOGA achieves the first, PF achieves the second by manipulating the flying controls. In some a/c you have to trim out a considerable push force, in some you pull the sidestick back and then let go,..... what about the VFW- Fokker 614? TOGA thrust presumably produces a nose-DOWN couple... and a DC-10 with one engine out will require slightly different technique to one with all engines operating.
The secret is training..... training .. practice .. and disciplined mental preparation before every approach.
If you perform a manual G/A you have a target thrust and a target pitch attitude to achieve, and a target speed to maintain. TOGA achieves the first, PF achieves the second by manipulating the flying controls. In some a/c you have to trim out a considerable push force, in some you pull the sidestick back and then let go,..... what about the VFW- Fokker 614? TOGA thrust presumably produces a nose-DOWN couple... and a DC-10 with one engine out will require slightly different technique to one with all engines operating.
The secret is training..... training .. practice .. and disciplined mental preparation before every approach.
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Interesting is a go-around in direct law, which will require pushing the stick when going toga. In direct law the AB is speedstable and manually trimmed.
Two different movements with the sidestick for the same maneuver.
Two different movements with the sidestick for the same maneuver.
Last edited by 737Jock; 1st Jan 2013 at 21:17.
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Good heavens, what a fruitless discussion.
This discussion has taught me that Airbus had never considered (or tested) that AOA probes (a very important item for collecting data to be used by the flight computers) can be blocked and therefore could not know the impact on automatic flight and thus had never issued a procedure for this kind of incident
This kind of accident was however easy to predict (even if he never occurred before) when you know in what environment these aircraft are operated
EVA Air pilots thus (against their will) made this test and found a procedure
This discovery is worth its weight in gold .. isn't it ?
Last edited by jcjeant; 1st Jan 2013 at 22:08.