Engine Fire on Take Off. TOGA application.
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Engine Fire on Take Off. TOGA application.
What are your views on the application of TOGA during a FLEX T/O with engine fire?
If the aircraft is a large twin jet and the fire bell goes off at V1, do you consider it wise or not to apply TOGA on both (assuming the a/c is climbing OK anyhow on FLEX power).
If the aircraft is a large twin jet and the fire bell goes off at V1, do you consider it wise or not to apply TOGA on both (assuming the a/c is climbing OK anyhow on FLEX power).
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If it goes at V1 then TOGA, because you simply don't know how it will climb - e.g. is the wing damaged too? If it goes once airborne and climb continues strongly then remain at FLEX but if in any doubt then apply TOGA and risk inducing failure in an already soon-to-be-shutdown engine for that extra few feet that may make all the difference...
Too simplistic?
Too simplistic?
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My understanding is that TOGA is not required. The whole point of runway analysis and the computation of flex thrust is to ensure that the aircraft will still meet all nominal climb requirements, including engine out, the same as it would if the takeoff were actually executed at the flex temperature.
That said, if one has presence of mind to apply TOGA thrust, then so much the better, as you would perform with that much more "comfort room" and, as stated above it would certainly be a good idea in the event of severe structural damage. On at least some (if not all) FADEC equipped aircraft, TOGA or APR is automatically applied once the FADEC detects the single engine schedule.
That said, if one has presence of mind to apply TOGA thrust, then so much the better, as you would perform with that much more "comfort room" and, as stated above it would certainly be a good idea in the event of severe structural damage. On at least some (if not all) FADEC equipped aircraft, TOGA or APR is automatically applied once the FADEC detects the single engine schedule.
Leave the thrust alone, just fly the aircraft. Don’t add more complications; the thrust increase will change the rudder requirement, which may feed into roll. Also don’t start introducing ‘what ifs’, the certification rules are such that an engine fire or malfunction is extremely unlikely to damage the wing. History / accident statistics show that we are in far more danger from a poorly flown climb out or a distraction of our own making than for the lack of thrust.
Why get over concerned about pumping 'X' kilos more fuel per second into a burning engine; you (we the industry) are quite happy about climbing to a safe height before completing shut down drills. For those who climb to 1000 ft aal, when on the WAT limit (200 ft/min) that’s 5 min of burning time, which is within most design assumptions and safe.
Why get over concerned about pumping 'X' kilos more fuel per second into a burning engine; you (we the industry) are quite happy about climbing to a safe height before completing shut down drills. For those who climb to 1000 ft aal, when on the WAT limit (200 ft/min) that’s 5 min of burning time, which is within most design assumptions and safe.
Having flown different types, some requiring TOGA thrust after an engine 'failure', some not, I would say there are arguments in both directions.
In the lower powered aircraft, it seemed like a good idea - get away from the ground because you'll soon be on one less. In some of the later turbofan twins, you were never short of power and full thrust could actually make handling more difficult.
Scenario: Light A/C, full derate (flex). V1/Vr probably Vmcg/Vmca limited. Adding asymmetric full thrust will put you near the edge of the controllability envelope for what gain? If you are fully derated there is ample fat in the system. I appreciate that the original question referred to a 'fire' as opposed to loss of thrust but a very high rate of climb is not always the best thing to have, especially if there is a low level off. There are some nasty little traps set for you if you end up in one of the 'altitude capture' APFD submodes which manufacturers love to include on their latest and greatest. These can be coped with but remember you have probably only just put an A/P in and are now concentrating on shutting down the 'right' engine, initiating an emergency turn, etc. I believe an Airbus (A340?) was lost during testing in similar circumstances.
To summarise: If TOGA thrust is a SOP, then follow it. If it is discretionary then I would advise caution at low speeds/weights. If you are not happy with the aircraft performance then add power until you are...
Aside: Some years ago the company I work for upgraded to a turbofan variant of a particular A/C but carried over most of the SOPs from the older type, including mandatory TOGA power. About a year later I heard that that at very low weights the FMC V-speeds could end up close, possibly below Vmca (full thrust) due to the FMC recalculating a new Vmca based on the derate. I don't know the truth but it was an interesting proposition: lo and behold suddenly new SOPs came out with minimum V1s and the removal of mandatory TOGA application...
In the lower powered aircraft, it seemed like a good idea - get away from the ground because you'll soon be on one less. In some of the later turbofan twins, you were never short of power and full thrust could actually make handling more difficult.
Scenario: Light A/C, full derate (flex). V1/Vr probably Vmcg/Vmca limited. Adding asymmetric full thrust will put you near the edge of the controllability envelope for what gain? If you are fully derated there is ample fat in the system. I appreciate that the original question referred to a 'fire' as opposed to loss of thrust but a very high rate of climb is not always the best thing to have, especially if there is a low level off. There are some nasty little traps set for you if you end up in one of the 'altitude capture' APFD submodes which manufacturers love to include on their latest and greatest. These can be coped with but remember you have probably only just put an A/P in and are now concentrating on shutting down the 'right' engine, initiating an emergency turn, etc. I believe an Airbus (A340?) was lost during testing in similar circumstances.
To summarise: If TOGA thrust is a SOP, then follow it. If it is discretionary then I would advise caution at low speeds/weights. If you are not happy with the aircraft performance then add power until you are...
Aside: Some years ago the company I work for upgraded to a turbofan variant of a particular A/C but carried over most of the SOPs from the older type, including mandatory TOGA power. About a year later I heard that that at very low weights the FMC V-speeds could end up close, possibly below Vmca (full thrust) due to the FMC recalculating a new Vmca based on the derate. I don't know the truth but it was an interesting proposition: lo and behold suddenly new SOPs came out with minimum V1s and the removal of mandatory TOGA application...
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I don't have any experience on derated takeoffs since we only use the flex option. It is my understanding however, that once you select a derated takeoff (as opposed to flex) you will only get the maximum derated power from the engine when you go to TOGA, rather than achieving the engine's full TOGA.
This is due to the arguments raised above as regards Vmca etc.
This is due to the arguments raised above as regards Vmca etc.
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In case of the assumed temperature method (Boeing) or Flex method (Airbus) I agree that full TO would be available on moving the thrust lever to the TOGA detent.
However, the derating concept is something different since you are derating the engine for that takeoff.
There is some info on http://www.b737.org.uk/assumedtemp.htm which could maybe explain the concept better than my posts. Having said that, I cannot comment on the B777 but I would have assumed that the concept is the same.
However, the derating concept is something different since you are derating the engine for that takeoff.
There is some info on http://www.b737.org.uk/assumedtemp.htm which could maybe explain the concept better than my posts. Having said that, I cannot comment on the B777 but I would have assumed that the concept is the same.
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The Boeing FCOM at my airline does indeed say that the first push of TOGA after takeoff will, among other things, remove the thrust "derates". The confusion lies in that at my airline we only use the Assumed Temperature method so that is all that will be removed.
It is always best to think of true derating as hanging a different size engine on the airplane, you can't very well go out and change that engine once airborne, at least not very easily. That differs from the AT method where you are just reducing the thrust setting. It is quite easy to push the thrust levers forward to recoup that reduction if necessary.
To add my two cents to the original question, no way would I add power for an engine fire indication. Engine fire does not equal loss of thrust. If anything you are struggling to get the nose down to level off at the MFRA with an engine fire, why exacerbate the problem with more thrust ?
Typhoonpilot
It is always best to think of true derating as hanging a different size engine on the airplane, you can't very well go out and change that engine once airborne, at least not very easily. That differs from the AT method where you are just reducing the thrust setting. It is quite easy to push the thrust levers forward to recoup that reduction if necessary.
To add my two cents to the original question, no way would I add power for an engine fire indication. Engine fire does not equal loss of thrust. If anything you are struggling to get the nose down to level off at the MFRA with an engine fire, why exacerbate the problem with more thrust ?
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Flex,is the same as derated power,just another Co's name for it.
Derated thrust meets the 'cert' criteria for the 2.4%gradient on ONE.The additional thrust at TOGA was a YAW consideration on the 747(wait until airborn).having said that some Co's call for TOGA thrust(on twins),every little bit helps, after takeoff.
It has been said that since the advent of 'reduced'thrust,in the 60's,the trend for full thrust when needed has been trained out of the knowledge loop(natural common sense).Ergo aircraft still flutter out o'the sky when a good handfull to the firewall would have helped.....
2.4% climb gradient=@150knts=2.5miles@min.
2.4% mile =144'/[email protected]=360'/minute rate o'climb
Derated thrust meets the 'cert' criteria for the 2.4%gradient on ONE.The additional thrust at TOGA was a YAW consideration on the 747(wait until airborn).having said that some Co's call for TOGA thrust(on twins),every little bit helps, after takeoff.
It has been said that since the advent of 'reduced'thrust,in the 60's,the trend for full thrust when needed has been trained out of the knowledge loop(natural common sense).Ergo aircraft still flutter out o'the sky when a good handfull to the firewall would have helped.....
2.4% climb gradient=@150knts=2.5miles@min.
2.4% mile =144'/[email protected]=360'/minute rate o'climb
Hudson, m&v, not all of us have the luxury of the high speed V2s. Where large flap angles are used for runway performance the climb speeds are low; thus 2.4 % at 110 Kts V2 and say a ground speed of 100 Kts, only gives approx 200 ft/min.
When considering SOPs, do we seek altitude for safety or time to asses the situation? More thrust should give more alt but less time at the critical period, and possibly at the expense of control with risk of error. There is probably no set answer, thus each to his own, but at least know why the SOP is written for a particular operating method and not the other.
When considering SOPs, do we seek altitude for safety or time to asses the situation? More thrust should give more alt but less time at the critical period, and possibly at the expense of control with risk of error. There is probably no set answer, thus each to his own, but at least know why the SOP is written for a particular operating method and not the other.
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Thank you all for your responses.
The reason I asked was that an instructor in my last sim ride was teaching TOGA as an SOP in all engine fail scenarios.
Its not written as an SOP in our books (its for 'consideration by the pilot') but he was utterly adamant that it should always be set.
I'll continue to 'consider it' first I think.
The reason I asked was that an instructor in my last sim ride was teaching TOGA as an SOP in all engine fail scenarios.
Its not written as an SOP in our books (its for 'consideration by the pilot') but he was utterly adamant that it should always be set.
I'll continue to 'consider it' first I think.
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idunno,what does your/the flight Manual say as to the application of 'thrust'with a fire/failure at takeoff.....Remember reduced /flex thrust a luxury of generous runway lengths(room to spare -ease up on the thrust).Once one has a failure,use what power you have available(KISS)
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Just a thought.
But on the boeing i fly, granted it is quite an old one (737-200, SP177 autopilot), on take off, u press the toga and once you get the throttle hold at circa 63 kts, it does'nt matter if you press the toga again. The throttles are in effect, in arm mode, where u can move them manually, but they will not move automatically. The throttles can be repositioned to any thrust setting, but only when u have throttle hold annunication. It is in effect the same as doing a level change descent. The throttles come back to idle, then they go into arm mode and u can set them wherever u want.
On a go around however, u press toga and u get x amount of thrust, press toga a second time and u get max go around thrust.
It may be different on this type, age of the aircraft and the engines being set by epr's, which must be set by 60 kts.
But as i said, just a thought.
Speedbird.
But on the boeing i fly, granted it is quite an old one (737-200, SP177 autopilot), on take off, u press the toga and once you get the throttle hold at circa 63 kts, it does'nt matter if you press the toga again. The throttles are in effect, in arm mode, where u can move them manually, but they will not move automatically. The throttles can be repositioned to any thrust setting, but only when u have throttle hold annunication. It is in effect the same as doing a level change descent. The throttles come back to idle, then they go into arm mode and u can set them wherever u want.
On a go around however, u press toga and u get x amount of thrust, press toga a second time and u get max go around thrust.
It may be different on this type, age of the aircraft and the engines being set by epr's, which must be set by 60 kts.
But as i said, just a thought.
Speedbird.
