Thrust on during flare...Q for AIRBUS test pilots...
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Give us an example of how a human could anticipate whereas the AP on an autoland can't.
The autopilot, and the airplane itself in FBW things, are flying MUCH better than human, as long as the situation does not go TOO DYNAMIC.. Look at the ATHR, or AT..aren't they that slow ??!! They are great to maintain the mach over the NAT, but cope poorly in gusty, shifting winds don't they ?
One day will come, where the quantum computers with a lot of fuzzy logic and 100000's of flights loaded will be able to mimic the 20k landings pilot, we are nowhere near this. ( proof being that drones are hand flown when dynamic kicks in)
As far as the original question for this thread is concerned, the answer was given extensively for the Airbus side; and this very sensitive part of flying (flare)with FBW airplanes is addressed differently depending on the manufacturers ; from the "stop trim" at 50 ft, to the derotation after Touchdown, ones would have to master a dozen of logics in order to be able to write a thorough answer.
Long live and prosper..
Last edited by CL300; 28th Mar 2014 at 09:06. Reason: mispelling
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Mate at the end of the day you fly your jet the way you want to......me? I'm going to keep it simple and follow the manufactures recommendations as to how to fly THEIR Aircraft.
For one simple reason------LITIGATION, if something un desired should happen I will have less chance of being screwed over in the subsequent court of enquiry...
Sounds silly but at the end of the day it's our jobs on the line each and every time we strap in to the Jet.
Remember big brother is watching everything you do, they will know what inputs you made to the controls every step of the way.....
For one simple reason------LITIGATION, if something un desired should happen I will have less chance of being screwed over in the subsequent court of enquiry...
Sounds silly but at the end of the day it's our jobs on the line each and every time we strap in to the Jet.
Remember big brother is watching everything you do, they will know what inputs you made to the controls every step of the way.....
lmao
Anyway sounds to me like we probably do the same things although you don't realize it!!
Whereas my explanation that thrust is energy and that the pitch controls what is done with this energy is valid in every flightphase.
Mate you are so far off the range with all the theory complicating it.
For gods sake it's simple
THRUST CONTROLS THE SPEED
PITCH CONTROLS THE PATH
In nearly all modes except Climb and Open descent where the ONLY WAY is for the Elevator to directly control the Pitch as the thrust is fixed.
Yes PITCH AND THRUST effect each other AND WORK HAND IN HAND, no arguments there, however in swept wing Airline transport category Jets there can be no other way. It's been this way since the advent of the Airline Jet.
Please don't complicate it anymore than that with your science books professor classroom theory.....it's not Rocket science.
I've been successfully flying these things for 25 years all over the world in rain hail typhoon snow storm safely and correctly according to the check and training departments of 3 highly safe World standard Airlines that follow Manufactures guidelines WITHOUT problems ever.
If me or my 3 Airlines were doing it wrong it would have been picked up and corrected before this.
You my friend have the bull by the horns.
For gods sake it's simple
THRUST CONTROLS THE SPEED
PITCH CONTROLS THE PATH
In nearly all modes except Climb and Open descent where the ONLY WAY is for the Elevator to directly control the Pitch as the thrust is fixed.
Yes PITCH AND THRUST effect each other AND WORK HAND IN HAND, no arguments there, however in swept wing Airline transport category Jets there can be no other way. It's been this way since the advent of the Airline Jet.
Please don't complicate it anymore than that with your science books professor classroom theory.....it's not Rocket science.
I've been successfully flying these things for 25 years all over the world in rain hail typhoon snow storm safely and correctly according to the check and training departments of 3 highly safe World standard Airlines that follow Manufactures guidelines WITHOUT problems ever.
If me or my 3 Airlines were doing it wrong it would have been picked up and corrected before this.
You my friend have the bull by the horns.
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So what you are saying is that you can't grasp aerodynamics and physics beyond a simplified method that changes in every flight regime.
And your right it's not rocket science, it's physics and aerodynamics.
BTW you forgot to answer my question regarding BUSS twice now!
So once more what happens if you keep the pitch constant (as you advocate for flying in BUSS) and keep the AOA in the green with thrust?
Speed changes, vertical speed changes or both change?
And just to put icing on the cake, what happens to the flightpath?
And your right it's not rocket science, it's physics and aerodynamics.
BTW you forgot to answer my question regarding BUSS twice now!
So once more what happens if you keep the pitch constant (as you advocate for flying in BUSS) and keep the AOA in the green with thrust?
Speed changes, vertical speed changes or both change?
And just to put icing on the cake, what happens to the flightpath?
I mean you haven't explained how you handfly an ILS using the A/THR.......
The recommended way to do it by both Airbus and Boeing....
You follow the PITCH BAR on the Flight Director which gives you guidance to follow the Glide Slope while the Auto Thrust closely keeps the Speed nailed.
This YOU CANNOT DENY is what happens.
What makes you think that you then do it ass about when you do manual thrust and suddenly using Pitch for speed and Thrust for sink rate.....
Come on do tell.
The recommended way to do it by both Airbus and Boeing....
You follow the PITCH BAR on the Flight Director which gives you guidance to follow the Glide Slope while the Auto Thrust closely keeps the Speed nailed.
This YOU CANNOT DENY is what happens.
What makes you think that you then do it ass about when you do manual thrust and suddenly using Pitch for speed and Thrust for sink rate.....
Come on do tell.
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PITCH CONTOLS THE PATH
Pitch controls speed and vertical speed.
Which is what I said.
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I don't normally handfly an ILS with A/T. Did you know this is an SOP in Lufthansa btw?
But as I can't control the thrust I have no other option then to fly like a reactive autopilot, with the thrust chasing my pitch variations.
In an A319 this can become a bit of a ballsache as the trim to compensate for the underslung engines is too slow.
I never said that this doesn't work. But you can also fly it the way noodle described and the way it's written in that naval aviator handbook. In the end it's all a simplified description of what actually happens.
Because pitch controls both speed and vertical speed, and thrust balances the forces that act on the aircraft through energy.
But as I can't control the thrust I have no other option then to fly like a reactive autopilot, with the thrust chasing my pitch variations.
In an A319 this can become a bit of a ballsache as the trim to compensate for the underslung engines is too slow.
I never said that this doesn't work. But you can also fly it the way noodle described and the way it's written in that naval aviator handbook. In the end it's all a simplified description of what actually happens.
Because pitch controls both speed and vertical speed, and thrust balances the forces that act on the aircraft through energy.
Sorry
About the BUSS.
Yes you will need to adjust pitch up and down 1 or 2 deg to maintain the GS but at the same time remaining in the Green band which is reasonably wide. Just like a normal approach.
So if you are a little high---push forward only 1 or 2 degrees to increase the ROD ( unfortunately you don't have a VSI so be careful ) ease back the thrust a little to stop speed increasing ( to keep in the green )
YES YOUR FLIGHT PATH GETS STEEPER
Once on GS pitch back up 1 or 2 deg and return the thrust to the baseline N1 of 49%.
Now maintain the Pitch to keep the path fairly constant and on the GS with small adjustments as required.
Maintain thrust fairly constant to keep inside the green as required.
The only difference to a normal approach is that you can't directly see the IAS
You can still vary Pitch to keep on a Glide Slope
You can still vary thrust to keep in the nice wide green band.
So in effect normal handling technique.
About the BUSS.
Yes you will need to adjust pitch up and down 1 or 2 deg to maintain the GS but at the same time remaining in the Green band which is reasonably wide. Just like a normal approach.
So if you are a little high---push forward only 1 or 2 degrees to increase the ROD ( unfortunately you don't have a VSI so be careful ) ease back the thrust a little to stop speed increasing ( to keep in the green )
YES YOUR FLIGHT PATH GETS STEEPER
Once on GS pitch back up 1 or 2 deg and return the thrust to the baseline N1 of 49%.
Now maintain the Pitch to keep the path fairly constant and on the GS with small adjustments as required.
Maintain thrust fairly constant to keep inside the green as required.
The only difference to a normal approach is that you can't directly see the IAS
You can still vary Pitch to keep on a Glide Slope
You can still vary thrust to keep in the nice wide green band.
So in effect normal handling technique.
Since a flightpath is speed over the ground (which is related to airspeed and you have ground speed mini) vs vertical speed
Originally Posted by 737jock
So you don't fix the pitch attitude when you fly in BUSS. Thanks for clarifying your error.
Last edited by Capn Bloggs; 28th Mar 2014 at 10:12.
Ok so why do you think the manufacturers decided that PITCH controls ROD and THRUST controls speed?
Surely they could have done it your way if wanted to and it was better??
They could have made the Aircraft Pitch up and down to maintain speed ( just like Open Descent ) and made the Thrust increase or decrease to keep the GS...
BUT THEY DIDN'T
By the way, Airbus and Boeing BOTH recommend use of the Auto Thrust ( Auto Throttle ) during manual flight.
Surely they could have done it your way if wanted to and it was better??
They could have made the Aircraft Pitch up and down to maintain speed ( just like Open Descent ) and made the Thrust increase or decrease to keep the GS...
BUT THEY DIDN'T
By the way, Airbus and Boeing BOTH recommend use of the Auto Thrust ( Auto Throttle ) during manual flight.
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Blogs if you don't have forward speed and you don't have vertical speed while up at 2000ft in the air you are hovering! That's not a path.
If you don't have forward speed but you descent at 700ft/min, you are dropping. The angle of your path is then 90 degrees.
If you fly at 130kts and you have no vertical speed you are flying straight and level. The angle of your path is 0 degrees.
So In order to fly a 3 degree path you need to go forward or backward (speed) and you need to descent or climb (vertical speed)
Mate study some physics!
If you don't have forward speed but you descent at 700ft/min, you are dropping. The angle of your path is then 90 degrees.
If you fly at 130kts and you have no vertical speed you are flying straight and level. The angle of your path is 0 degrees.
So In order to fly a 3 degree path you need to go forward or backward (speed) and you need to descent or climb (vertical speed)
Mate study some physics!
I've updated my BUSS answer!!
Yes of course with the BUSS you vary the Pitch to maintain the GS as normal and use the Thrust to hold the green, I was trying to highlight that to stay in the green band you adjust thrust whilst keeping pitch steady. Naturally you will need to vary pitch up and down a bit to maintain the GS as well.
BUT the important bit is that it uses the same technique as a normal approach.
Sorry for the confusion.
Without the BUSS You setup the Pitch ( then adjust to stay on the GS ) and Thrust and basically hope the IAS is ok with a fairly wide margin of error on your side....
Yes of course with the BUSS you vary the Pitch to maintain the GS as normal and use the Thrust to hold the green, I was trying to highlight that to stay in the green band you adjust thrust whilst keeping pitch steady. Naturally you will need to vary pitch up and down a bit to maintain the GS as well.
BUT the important bit is that it uses the same technique as a normal approach.
Sorry for the confusion.
Without the BUSS You setup the Pitch ( then adjust to stay on the GS ) and Thrust and basically hope the IAS is ok with a fairly wide margin of error on your side....
Last edited by nitpicker330; 28th Mar 2014 at 10:39.
Ahhh the great guru of all things Aviation comes back into play......
Noodle....
Anything intelligent to add?
I cannot do anymore than I have to point out the way Airbus wants it done.
I've quoted heaven a verse from their own FCTM and A330 Instructors manual..
What you don't believe THEM either?
Would you like me to ring up their chief test Pilot in Toulouse.
Noodle....
Anything intelligent to add?
I cannot do anymore than I have to point out the way Airbus wants it done.
I've quoted heaven a verse from their own FCTM and A330 Instructors manual..
What you don't believe THEM either?
Would you like me to ring up their chief test Pilot in Toulouse.
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to hold or not to hold thrust during flare
...that was the original thread question I think?
Hold if necessary but be prepared for a Balked Landing Go Around as to REQUIRE more power than you normally need during flare with its consequential possible dangers on the landing run available..means you are outside the envelope of "stabiized approach". Nothing is stable (strictly speaking) about flying the ILS I agree with 737jock..if stable the plane would automatically realign with ILS upon any displa.cement..like Autocoupled approach! More appropriate if we talk about a Energy state stability rather than flight state stability. On the flare if you require to hold the power..it means your energy state is unstable..and the alarming impending sink rate is your cue.
Keep the AT on Approach mode...then you don't have to worry about this debate!
Hold if necessary but be prepared for a Balked Landing Go Around as to REQUIRE more power than you normally need during flare with its consequential possible dangers on the landing run available..means you are outside the envelope of "stabiized approach". Nothing is stable (strictly speaking) about flying the ILS I agree with 737jock..if stable the plane would automatically realign with ILS upon any displa.cement..like Autocoupled approach! More appropriate if we talk about a Energy state stability rather than flight state stability. On the flare if you require to hold the power..it means your energy state is unstable..and the alarming impending sink rate is your cue.
Keep the AT on Approach mode...then you don't have to worry about this debate!
Already answered that page 7 back using FCTM notes....on reply #127
Maybe 737Jock and Noodle should read the SUPP PROC Power Plant and the FCTM section manual quotes again and really read them this time.
Ahh stuff it I'll post it again for them.....
SUPP PROC POWER PLANT--
USE OF AUTOTHRUST IN APPROACH The pilot should use autothrust for approaches. On final approach, it usually gives more accurate speed control, although in turbulent conditions the actual airspeed may vary from the target speed, by as much as 5 kt. Although the changeover between auto and manual thrust is easy to make with a little practice, the pilot should, when using autothrust for the final approach, keep it engaged until he retards the thrust levers to idle for touchdown. If the pilot is going to make the landing using manual thrust, he should disconnect the A/THR by the time he has reached 1 000 ft on the final approach. If he makes a shallow flare, with A/THR engaged, it will increase thrust to maintain the approach speed until he pulls the thrust levers back to idle. Therefore, he should avoid making a shallow flare, or should retard the thrust levers as soon as it is no longer necessary to carry thrust, and if necessary before he receives the “retard” reminder. Although use of the autothrust is recommended for the entire approach, this does not absolve the pilot from his responsibility to monitor its performance, and to disconnect it if it fails to maintain speed at the selected value. Such monitoring should include checking on whether or not the managed speed, calculated by the FMGEC, is reasonable.
And the A330 FCTM quotes---
USE OF A/THR The pilot should use the A/THR for approaches as it provides accurate speed control The pilot will keep the hand on the thrust levers so as to be prepared to react if needed.
TRAJECTORY STABILIZATION The first prerequisite for safe final approach and landing is to stabilize the aircraft on the final approach flight path laterally and longitudinally, in landing configuration, at VAPP speed, i.e: • Only small corrections are necessary to rectify minor deviations from stabilized conditions • The thrust is stabilized, usually above idle, to maintain the target approach speed along the desired final approach path
FINAL APPROACH Roll out of the turn on the extended runway centreline and maintain VAPP. Thrust should be stable by 1 000 ft. Use the speed trend arrow to anticipate thrust changes and the FPV to monitor approach path deviations. Use available G/S and/or PAPIs as well as the visual picture to assist in maintaining a stable approach. A continuous visual/instrument scan is required to fly a successful approach. An effective scan will assist in highlighting small errors, allowing small, early corrections to be made. A 3 ° slope will normally be flown with a ROD of approximately 700 ft/min; a higher ROD is an indication that the aircraft is about to descend below the ideal approach path. A small correction of approx 1 ° of pitch will change the ROD by approximately 100 ft/min. Azimuth errors will require bank angle changes both to stop the drift and then to recover to the centreline. Avoid using bank angles greater than 10 ° for small corrections.
Maybe 737Jock and Noodle should read the SUPP PROC Power Plant and the FCTM section manual quotes again and really read them this time.
Ahh stuff it I'll post it again for them.....
SUPP PROC POWER PLANT--
USE OF AUTOTHRUST IN APPROACH The pilot should use autothrust for approaches. On final approach, it usually gives more accurate speed control, although in turbulent conditions the actual airspeed may vary from the target speed, by as much as 5 kt. Although the changeover between auto and manual thrust is easy to make with a little practice, the pilot should, when using autothrust for the final approach, keep it engaged until he retards the thrust levers to idle for touchdown. If the pilot is going to make the landing using manual thrust, he should disconnect the A/THR by the time he has reached 1 000 ft on the final approach. If he makes a shallow flare, with A/THR engaged, it will increase thrust to maintain the approach speed until he pulls the thrust levers back to idle. Therefore, he should avoid making a shallow flare, or should retard the thrust levers as soon as it is no longer necessary to carry thrust, and if necessary before he receives the “retard” reminder. Although use of the autothrust is recommended for the entire approach, this does not absolve the pilot from his responsibility to monitor its performance, and to disconnect it if it fails to maintain speed at the selected value. Such monitoring should include checking on whether or not the managed speed, calculated by the FMGEC, is reasonable.
And the A330 FCTM quotes---
USE OF A/THR The pilot should use the A/THR for approaches as it provides accurate speed control The pilot will keep the hand on the thrust levers so as to be prepared to react if needed.
TRAJECTORY STABILIZATION The first prerequisite for safe final approach and landing is to stabilize the aircraft on the final approach flight path laterally and longitudinally, in landing configuration, at VAPP speed, i.e: • Only small corrections are necessary to rectify minor deviations from stabilized conditions • The thrust is stabilized, usually above idle, to maintain the target approach speed along the desired final approach path
FINAL APPROACH Roll out of the turn on the extended runway centreline and maintain VAPP. Thrust should be stable by 1 000 ft. Use the speed trend arrow to anticipate thrust changes and the FPV to monitor approach path deviations. Use available G/S and/or PAPIs as well as the visual picture to assist in maintaining a stable approach. A continuous visual/instrument scan is required to fly a successful approach. An effective scan will assist in highlighting small errors, allowing small, early corrections to be made. A 3 ° slope will normally be flown with a ROD of approximately 700 ft/min; a higher ROD is an indication that the aircraft is about to descend below the ideal approach path. A small correction of approx 1 ° of pitch will change the ROD by approximately 100 ft/min. Azimuth errors will require bank angle changes both to stop the drift and then to recover to the centreline. Avoid using bank angles greater than 10 ° for small corrections.
Last edited by nitpicker330; 28th Mar 2014 at 11:00.
Surely the last paragraph advising the a higher ROD than 700 fpm will result in going below GS and a 1 deg pitch correction causes 100 fpm change IS ALL YOU NEED TO SEE HOW THEY WANT YOU TO CORRECT IT....
I mean do they have to hand feed you too????
I mean do they have to hand feed you too????
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An amazing level of blinkerdness being displayed by some here.
I don't think anyone is disputing that both thrust and pitch affect both speed and flight path. The question is which produces the finer control and is more appropriate. The answer to that, like so many things in aviation, is - it depends.
It depends on:
a) the characteristics of the aircraft you are flying
b) the critical task you are trying to achieve.
I'm afraid, NoodleAir, that your unswerving reliance on "Aerodynamics for Naval Aviators" as the bible for all things is somewhat misplaced. It was written in the 60's for - surprise, surprise - Naval Aviators. They were flying machines that were, by today's standards:
-Small
-Light
-Low wing loading
-possessing a "sharp" drag curve, i.e. drag increases quickly as you slow below Vmd
-often had flap blowing systems that make lift directly related to engine power setting.
-And their critical task was landing-on to a carrier; a visual approach flown at considerably closer to the stall speed than would be used for a civil aircraft.
With the exception of the last these characteristics are similar to a light propeller aircraft of today, and I would be the first to say that the best system to use in those is pitch for speed, power for flight path.
However, we are discussing modern transport jets. These are relatively:
-Large
-Heavy
-High wing loading
-with a very flat drag curve
-No direct relationship between lift and engine power/thrust setting.
-Whose critical task is a precision instrument approach to low or no visual minima.
For these 40 years of line experience from all manufacturers has shown that the best technique for line service (on approach) is pitch for flight path and thrust for speed. Which is why it is recommended in the manuals, taught at all the schools and used by the automatic systems.
Your reference to test pilots is unfortunately a red herring, because many techniques are used in test flying to enable repeatability and measurability against requirements that are different from line flying techniques. In this specific case, if you are trying to measure landing distance, speed control is more critical than the actual touchdown point which will be recorded by the cameras, so the more precise control is used.
I don't think anyone is disputing that both thrust and pitch affect both speed and flight path. The question is which produces the finer control and is more appropriate. The answer to that, like so many things in aviation, is - it depends.
It depends on:
a) the characteristics of the aircraft you are flying
b) the critical task you are trying to achieve.
I'm afraid, NoodleAir, that your unswerving reliance on "Aerodynamics for Naval Aviators" as the bible for all things is somewhat misplaced. It was written in the 60's for - surprise, surprise - Naval Aviators. They were flying machines that were, by today's standards:
-Small
-Light
-Low wing loading
-possessing a "sharp" drag curve, i.e. drag increases quickly as you slow below Vmd
-often had flap blowing systems that make lift directly related to engine power setting.
-And their critical task was landing-on to a carrier; a visual approach flown at considerably closer to the stall speed than would be used for a civil aircraft.
With the exception of the last these characteristics are similar to a light propeller aircraft of today, and I would be the first to say that the best system to use in those is pitch for speed, power for flight path.
However, we are discussing modern transport jets. These are relatively:
-Large
-Heavy
-High wing loading
-with a very flat drag curve
-No direct relationship between lift and engine power/thrust setting.
-Whose critical task is a precision instrument approach to low or no visual minima.
For these 40 years of line experience from all manufacturers has shown that the best technique for line service (on approach) is pitch for flight path and thrust for speed. Which is why it is recommended in the manuals, taught at all the schools and used by the automatic systems.
Your reference to test pilots is unfortunately a red herring, because many techniques are used in test flying to enable repeatability and measurability against requirements that are different from line flying techniques. In this specific case, if you are trying to measure landing distance, speed control is more critical than the actual touchdown point which will be recorded by the cameras, so the more precise control is used.