BA056 JNB-LHR Incident.
Usual disclaimers apply!
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From memory, the LH at NBO had all L/E stowed, sad day for them
Now a bit rusty here but.....
In that case, the engines in those days were very 'strapped' for power especially at a place like NBO and bleeds off takeoff was reqd.
The F/E had selected the pylon valves (bleeds) closed after start and at the time there were no warning lights on the front P3 panel for L/E position/disagree. (amber and green). The trailing edges deployed, albeit slowly as the EDP's were producing pressure, but without the pneumatics the L/E flaps all remained stowed.
That indication light mod. on the P3 panel came about a result of that accident.
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@Turin
THX buddy for yr post, had my description only in german. U R right
Auto LE retraction is controlled by switches in the thrustlever assembly and at least 1+4 or 2+3 must be physically activated by moving the levers in direction REVERSE > 6 degrees
Strange post I guess ...
I am confused, surely the LE devices would extend again as soon as the craft got airborne.
Auto LE retraction is controlled by switches in the thrustlever assembly and at least 1+4 or 2+3 must be physically activated by moving the levers in direction REVERSE > 6 degrees
Strange post I guess ...
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Quick update:
The stick shaker kicked in at 12 feet and due to the quick reaction of the crew advancing the throttles and getting the gear up 'sharpish' the stick shaker stopped at 40', no level off as mentioned in my previous post.
As the aircraft accelerated the LE slats redeployed at about 160'.
Nicely handled!
The stick shaker kicked in at 12 feet and due to the quick reaction of the crew advancing the throttles and getting the gear up 'sharpish' the stick shaker stopped at 40', no level off as mentioned in my previous post.
As the aircraft accelerated the LE slats redeployed at about 160'.
Nicely handled!
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On rotate out of Johannesburg the aircraft systems gave a spurious warning that the thrust reverser doors (Used on landing to assist in braking the aircraft) on engines 2 + 3 were unlocked (possibly open or deployed leading to the engine thrust being deployed forward not rearward).
A potentially dangerous situation as a thrust reverser deployment in flight, especially at low speed/low level can cause a disastrous departure from controlled flight! The system has three interlocks which should prevent actual deployment in flight.
The crew could not know what that actual deployment of the thrust reverser doors was, however an actual deployment would most certainly be felt by the flying pilot!
As a damage security system the 744 automatically retracts the mid and inboard leading edge slats to prevent damage to the slats from the thrust of the engine now coming forward. As JNB is a high airfield in hot conditions with a heavy aircraft these lift enhancing devices on the leading edge are vital, all take off and climb out speeds would be calculated using LE slats deployed. Loss of those, without quick intervention could lead to a stall.
The aircraft stick shaker is there to warn the crew of impending approach toward the stall. Thus, at the onset of stick shaker the crew selected full Take Off/ Go Around (TOGA) power, brought the landing gear up to reduce drag and flew the aircraft away from a potentially dangerous situation. Normal take offs are conducted at a 'flexible' power dependant on the conditions of the day to save on engine wear.
Excellently handled and I think I can see the next 6 monthly simulator check scenario now.
A potentially dangerous situation as a thrust reverser deployment in flight, especially at low speed/low level can cause a disastrous departure from controlled flight! The system has three interlocks which should prevent actual deployment in flight.
The crew could not know what that actual deployment of the thrust reverser doors was, however an actual deployment would most certainly be felt by the flying pilot!
As a damage security system the 744 automatically retracts the mid and inboard leading edge slats to prevent damage to the slats from the thrust of the engine now coming forward. As JNB is a high airfield in hot conditions with a heavy aircraft these lift enhancing devices on the leading edge are vital, all take off and climb out speeds would be calculated using LE slats deployed. Loss of those, without quick intervention could lead to a stall.
The aircraft stick shaker is there to warn the crew of impending approach toward the stall. Thus, at the onset of stick shaker the crew selected full Take Off/ Go Around (TOGA) power, brought the landing gear up to reduce drag and flew the aircraft away from a potentially dangerous situation. Normal take offs are conducted at a 'flexible' power dependant on the conditions of the day to save on engine wear.
Excellently handled and I think I can see the next 6 monthly simulator check scenario now.
Usual disclaimers apply!
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Excellently handled and I think I can see the next 6 monthly simulator check scenario now.
Potentially this would affect all 744 operators as the A/F systems are all the same it's just the T/R modus operandi that differs!
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Not wanting to take anything away from the crew, but we are taught to keep the gear down in a near-stall close to the ground situation, until clear of terrain and out of stall airspeed. This is to prevent extra drag from gear door extension in a critical phase of flight and also if ground contact becomes unavoidable, it should happen with the gear down rather than in the middle of a retraction sequence.
Your thoughts?
Your thoughts?
Last edited by Wytnucls; 27th May 2009 at 02:23.
Controversial, moi?
Thus, at the onset of stick shaker the crew selected full Take Off/ Go Around (TOGA) power, brought the landing gear up to reduce drag....
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I wonder it got airborne at all with that asymetric lift due to LE devices on one side retracted.The AA DC-10 crash at ORD comes to my mind.
I would have thought of a severe amount of roll to be encountered.
If the crew was able to recover that----hell of a job
I would have thought of a severe amount of roll to be encountered.
If the crew was able to recover that----hell of a job
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I think the slat retraction would be symmetrical.
M.Mouse - it's not a published procedure on the 744 to raise the gear in a stall situation but I'm sure more detail will be available through the usual channels shortly.
M.Mouse - it's not a published procedure on the 744 to raise the gear in a stall situation but I'm sure more detail will be available through the usual channels shortly.
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CptRegionalJet
It was the LE slats on both sides that retracted due to 2+3 being both inboard engines. As you say though it could have been interesting if it had only been one reverser! [edit] I seem to remember that the system would retract both LE slats symmetrically irrespective of which engine was causing the problem to prevent asymmetric wing loading.
As to the SOP for retracting the gear I have to come clean and say I don't know as I don't currently fly the 744. However I would suggest that the drag caused during retraction could possibly even be less than when the gear is fully deployed judging by the number of wheels dangling down and their retraction sequence. At the time the desire to get the gear up and hence drag down to cancel the stick shaker would probably have been foremost. Especially if there was no suitable terrain below anyway.
Best to ask someone current on the aircraft.
It was the LE slats on both sides that retracted due to 2+3 being both inboard engines. As you say though it could have been interesting if it had only been one reverser! [edit] I seem to remember that the system would retract both LE slats symmetrically irrespective of which engine was causing the problem to prevent asymmetric wing loading.
As to the SOP for retracting the gear I have to come clean and say I don't know as I don't currently fly the 744. However I would suggest that the drag caused during retraction could possibly even be less than when the gear is fully deployed judging by the number of wheels dangling down and their retraction sequence. At the time the desire to get the gear up and hence drag down to cancel the stick shaker would probably have been foremost. Especially if there was no suitable terrain below anyway.
Best to ask someone current on the aircraft.
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744 SOP is to leave the gear down in any situation where a positive rate of climb is not being achieved, (for example a Windshear Go-around). Only when a positive ROC is achieved do you select Gear Up.
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wobble2plank,
The drag would not be less during retraction because, if you select gear up, the landing gear bay doors have to open in order to allow for gear retraction, trust me those doors are massive, add that to the landing gear itself and it would cause way too much drag, so the last think you want to do in a situation near the stall or multiple engine malfunction on take off is to retract the gear...especially in JNB.
Bokkie449
The drag would not be less during retraction because, if you select gear up, the landing gear bay doors have to open in order to allow for gear retraction, trust me those doors are massive, add that to the landing gear itself and it would cause way too much drag, so the last think you want to do in a situation near the stall or multiple engine malfunction on take off is to retract the gear...especially in JNB.
Bokkie449
Controversial, moi?
So there we have it Wobble has some accurate information but cannot leave it at that and proceeds to explain incorrectly the rest of the event.
Why cannot people just post what they KNOW to be factual?
Why cannot people just post what they KNOW to be factual?
I'm asking this as a PPL and therefore as a non-B744 driver, but would the fact that the takeoff was after sunset have made it better or worse for the crew.
Obviously it was slightly less "hot" (but still high), but is it easier to run through options available only 12 - 40 ft off the ground during the day, or at night.
Are the instruments/warning lights clearer? Does it help seeing the ground in daylight, or is it all pretty moot in the timeframe they had to react?
Obviously it was slightly less "hot" (but still high), but is it easier to run through options available only 12 - 40 ft off the ground during the day, or at night.
Are the instruments/warning lights clearer? Does it help seeing the ground in daylight, or is it all pretty moot in the timeframe they had to react?
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The question should be whether they did actually retract the gear then, and if they did, was it the optimal reaction? It's a serious enough incident to warrant speculation, but we'll only know when the facts come to light.
TN
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Doesn't it worry you?
All you professional guys out there - doesn't a story like this worry the hell, out of you (and the pax sitting behind you)?
You've done all the calculations, correctly set the aircraft up ready for takeoff according to weight, altitude, weather conditions etc. Are you not completely in control during the critical 2-3 minutes that follow?
When I push the throttle forward in my C152 and commit to takeoff I expect to be in total control for every aspect of the flight thereafter including an EFTO.
This story suggests that a computer (a machine of questionable integrity programmed by a nerd who might or might not have been having a bad day) decides that a major mechanical malfunction has taken place (when it hadn't) then retracts essential lift devices at the very moment they are needed most and all of this happens between 12 and 40 feet above ground. Whatever happened to PIC?
Thank God the crew were experienced enough to take corrective action. How many Third World crews would have been able to do the same or ended up splattered all over the airfield perimeter?
You've done all the calculations, correctly set the aircraft up ready for takeoff according to weight, altitude, weather conditions etc. Are you not completely in control during the critical 2-3 minutes that follow?
When I push the throttle forward in my C152 and commit to takeoff I expect to be in total control for every aspect of the flight thereafter including an EFTO.
This story suggests that a computer (a machine of questionable integrity programmed by a nerd who might or might not have been having a bad day) decides that a major mechanical malfunction has taken place (when it hadn't) then retracts essential lift devices at the very moment they are needed most and all of this happens between 12 and 40 feet above ground. Whatever happened to PIC?
Thank God the crew were experienced enough to take corrective action. How many Third World crews would have been able to do the same or ended up splattered all over the airfield perimeter?
Last edited by Xeque; 14th May 2009 at 13:32.