takeoff low weight , no reduced thrust, high pitch
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takeoff low weight , no reduced thrust, high pitch
Hi
I want to know what do you think about this.
Take off without load and low fuel for a short ferry flight.
Meteo Condition: Gusting winds up to 40 kt and light to moderate turbulence. So I prefer not to do a reduced takeoff thrust.
The accelaration will be very fast. So if I want to climb at V2 + 20 my pitch would be 25 degree or perhaps more. And It will require a fast than normal rotation to avoid a faster speed.
In that situation is not better a higher than v2 +20 climb ? The rotation could be smoother and we have a margin to avoid lost of speed due to gusting winds.
What do you think? Or what would you do on such a situation ?
Thank you very much
Ale
I want to know what do you think about this.
Take off without load and low fuel for a short ferry flight.
Meteo Condition: Gusting winds up to 40 kt and light to moderate turbulence. So I prefer not to do a reduced takeoff thrust.
The accelaration will be very fast. So if I want to climb at V2 + 20 my pitch would be 25 degree or perhaps more. And It will require a fast than normal rotation to avoid a faster speed.
In that situation is not better a higher than v2 +20 climb ? The rotation could be smoother and we have a margin to avoid lost of speed due to gusting winds.
What do you think? Or what would you do on such a situation ?
Thank you very much
Ale
alistomalibu
Firstly depending on your type, a faster rotation may give you a fair bit of grief as your backend smacks the hard stuff. Stick with your normal rotation rate.
Secondly check your Limitations section. You may have a pitch limit, ie MD80 series are limited to 20 degrees.
V2 +20 in gusty 40 knot winds.......er, perhaps afaster climb would be more appropriate.
High pitch angles, low fuel, not a good combination.
Where should I send the flowers.
Maui
Firstly depending on your type, a faster rotation may give you a fair bit of grief as your backend smacks the hard stuff. Stick with your normal rotation rate.
Secondly check your Limitations section. You may have a pitch limit, ie MD80 series are limited to 20 degrees.
V2 +20 in gusty 40 knot winds.......er, perhaps afaster climb would be more appropriate.
High pitch angles, low fuel, not a good combination.
Where should I send the flowers.
Maui
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HI
a) rotate normally to avoid a tail strike or an engine pod strike depending
on your aircraft type
b) go to your max allowed pitch attitude..sometimes the limits(e.g 25 deg)
is set for pax comfort
c) check your max ias for the T/O flap settings, if max pitch attitude is
reached and airspeed is still increasing be ready to retract flaps to the
next setting and then all the way up
OR
ask for the aircraft to be loaded with ballast and/or extra fuel to offset all of the above
why not consider a lower T/O flap setting(the lowest) according to your aircraft type
a) rotate normally to avoid a tail strike or an engine pod strike depending
on your aircraft type
b) go to your max allowed pitch attitude..sometimes the limits(e.g 25 deg)
is set for pax comfort
c) check your max ias for the T/O flap settings, if max pitch attitude is
reached and airspeed is still increasing be ready to retract flaps to the
next setting and then all the way up
OR
ask for the aircraft to be loaded with ballast and/or extra fuel to offset all of the above
why not consider a lower T/O flap setting(the lowest) according to your aircraft type
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Bangladesh Biman had this very problem years ago at Singapore (Paya Lebar) wherein...
Light weight due to short flight (KUL) and minimum fuel load.
Gusting winds.
Rapid rotation followed by extremely high pitch attitude resulted in engines flaming out (tank ports uncovered) and the aircraft crashed near the airport boundry.
Best idea, stick to normal rotation technique, limit body angle to the max allowed for type, and accept the speed that follows.
Less grief this way...
Light weight due to short flight (KUL) and minimum fuel load.
Gusting winds.
Rapid rotation followed by extremely high pitch attitude resulted in engines flaming out (tank ports uncovered) and the aircraft crashed near the airport boundry.
Best idea, stick to normal rotation technique, limit body angle to the max allowed for type, and accept the speed that follows.
Less grief this way...
Empty ferries, limiting speeds, and SOPs
This dilemma even occurs in relatively calm conditions off a short runway – perhaps one not approved by your company for reduced thrust. I remember ferrying an empty VC10 out of Hurn to Gatwick after a charter – 85,000 lbs thrust on a 90-tonne aeroplane. Empty twins are particularly likely to face it. Even an A320 may deliver 50,000 lbs thrust at a weight below 50 tonnes.
I am assuming you are talking about something comparable.
I agree with most of what maui, bflyer and 411A have said. The limiting speeds are the problem, particularly if you must use full power for T/O because of forecast (or predictable) wind-shear. But I do not like the idea of retracting the flaps during a gust-created rise of IAS. The speed rise could be short-lived.
The trouble with modern airliners is that you are all encouraged to use full automation if it is available. This is fine until you are in a non-standard situation, not predicted by the auto-flight systems designers. One which your desk-bound flight manager, who is responsible for SOPs, may never have experienced on your type.
My suggestion is that, as soon as airborne and terrain clearance is assured, the power can be reduced considerably – i.e., below climb power if necessary – to avoid risk of exceeding the limit speeds for flaps/slats (and even gear-retraction, if it has been delayed for some reason). Speed will continue to be controlled by elevator.
If you are using the autopilot and auto-thrust, the SOP will typically assume thrust reduction to climb power at 1000 ft aal or higher, followed – usually immediately – by acceleration during clean-up. Many auto-flight systems, however, allow the thrust-reduction and acceleration altitudes to be preset by the crew separately.
As soon as safely in the initial climb, at perhaps V2 + 25, pre-empt the situation by reducing power to climb thrust, or lower if necessary. The AFS will be using elevator to control speed. It is vital, of course, to ensure obstacle clearance. In hilly terrain, performance (net take-off flight path) requirements may not be achieved if you overdo the thrust reduction. But if you ensure that the pitch attitude remains at or above the normal target figure for all-engine take-off thrust, that will not be a problem.
If the need to reduce power below climb thrust means removing auto-thrust, so be it. [On the A320, I believe, it is possible to limit the thrust to a lower figure without removing A/THR.] This early thrust reduction should not change the auto-flight mode to acceleration mode prematurely, PROVIDED the acceleration altitude has been preset correctly to an appropriate figure.
Once acceleration altitude has been reached, the risk in your scenario is that you will accelerate too rapidly during clean-up. The trade-off between acceleration and climb-rate that the AFS uses is supposed to cover this, but may not. If you modify the vertical speed (i.e., increase it) by selecting VS mode, the AFS may reduce the speed target to the current speed, so you will have to reselect the target speed. Instead, consideration should be given to reducing power below climb-thrust (if you have not already done so). Whatever thrust you set, you must once again ensure that the climb angle is more than enough to clear any obstacles. This is where you will have to use what is subjectively referred to (mainly by flight-crew managers) as "your judgement".
The management of obstacle clearance, and the potential pitfalls of using a mixture of manual and automatic systems (or even removing the automation completely), are the main issues that make it difficult to create SOPs for your scenario. But no one will thank you for over-speeding the aeroplane while following SOPs to the letter – certainly not your flight manager.
That's what you're paid all that money for, I guess...
I am assuming you are talking about something comparable.
I agree with most of what maui, bflyer and 411A have said. The limiting speeds are the problem, particularly if you must use full power for T/O because of forecast (or predictable) wind-shear. But I do not like the idea of retracting the flaps during a gust-created rise of IAS. The speed rise could be short-lived.
The trouble with modern airliners is that you are all encouraged to use full automation if it is available. This is fine until you are in a non-standard situation, not predicted by the auto-flight systems designers. One which your desk-bound flight manager, who is responsible for SOPs, may never have experienced on your type.
My suggestion is that, as soon as airborne and terrain clearance is assured, the power can be reduced considerably – i.e., below climb power if necessary – to avoid risk of exceeding the limit speeds for flaps/slats (and even gear-retraction, if it has been delayed for some reason). Speed will continue to be controlled by elevator.
If you are using the autopilot and auto-thrust, the SOP will typically assume thrust reduction to climb power at 1000 ft aal or higher, followed – usually immediately – by acceleration during clean-up. Many auto-flight systems, however, allow the thrust-reduction and acceleration altitudes to be preset by the crew separately.
As soon as safely in the initial climb, at perhaps V2 + 25, pre-empt the situation by reducing power to climb thrust, or lower if necessary. The AFS will be using elevator to control speed. It is vital, of course, to ensure obstacle clearance. In hilly terrain, performance (net take-off flight path) requirements may not be achieved if you overdo the thrust reduction. But if you ensure that the pitch attitude remains at or above the normal target figure for all-engine take-off thrust, that will not be a problem.
If the need to reduce power below climb thrust means removing auto-thrust, so be it. [On the A320, I believe, it is possible to limit the thrust to a lower figure without removing A/THR.] This early thrust reduction should not change the auto-flight mode to acceleration mode prematurely, PROVIDED the acceleration altitude has been preset correctly to an appropriate figure.
Once acceleration altitude has been reached, the risk in your scenario is that you will accelerate too rapidly during clean-up. The trade-off between acceleration and climb-rate that the AFS uses is supposed to cover this, but may not. If you modify the vertical speed (i.e., increase it) by selecting VS mode, the AFS may reduce the speed target to the current speed, so you will have to reselect the target speed. Instead, consideration should be given to reducing power below climb-thrust (if you have not already done so). Whatever thrust you set, you must once again ensure that the climb angle is more than enough to clear any obstacles. This is where you will have to use what is subjectively referred to (mainly by flight-crew managers) as "your judgement".
The management of obstacle clearance, and the potential pitfalls of using a mixture of manual and automatic systems (or even removing the automation completely), are the main issues that make it difficult to create SOPs for your scenario. But no one will thank you for over-speeding the aeroplane while following SOPs to the letter – certainly not your flight manager.
That's what you're paid all that money for, I guess...
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It shouldn't be a big deal,
Rotate at the usual rate to the pitch limit, then as had been said before, take climb thrust..or some other reduction that allows the aeroplane to settle down into a stable speed regime.
Try a light weight 757 weighing around 65 tonnes (including fuel) with a thrust reverser locked out..which means its a full power takeoff.
i.e. 65 tonnes of mass being shifted by about 40 tonnes of thrust..and yet..planning ahead means its no problem
Rotate at the usual rate to the pitch limit, then as had been said before, take climb thrust..or some other reduction that allows the aeroplane to settle down into a stable speed regime.
Try a light weight 757 weighing around 65 tonnes (including fuel) with a thrust reverser locked out..which means its a full power takeoff.
i.e. 65 tonnes of mass being shifted by about 40 tonnes of thrust
..and yet..planning ahead means its no problem
