ALPHA PROT/FLOOR/MAX
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ALPHA PROT/FLOOR/MAX
Hi everyone,
I know that there are some posts on this but I just would like to check all these:
Alpha floor is a protection and thrust goes to TOGA.
At alpha max (if you reach it
), it will remain like this but when you will leave the stick, it will go towards Alpha protection and give the alpha floor.
But is the Alpha prot basically where Alpha floor arms? Or does alpha floor come in Alpha protection?
Is there something for take-off? I had read something with 5 seconds...
Alpha protection: Around 15 degrees AoA
Alpha Max: Around 18 degrees AoA
And at which angle does the alpha floor bring you?
Please clear me in these doubts!
Thanks
I know that there are some posts on this but I just would like to check all these:
Alpha floor is a protection and thrust goes to TOGA.
At alpha max (if you reach it
), it will remain like this but when you will leave the stick, it will go towards Alpha protection and give the alpha floor.But is the Alpha prot basically where Alpha floor arms? Or does alpha floor come in Alpha protection?
Is there something for take-off? I had read something with 5 seconds...
Alpha protection: Around 15 degrees AoA
Alpha Max: Around 18 degrees AoA
And at which angle does the alpha floor bring you?
Please clear me in these doubts!
Thanks
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Go to smartcockpit.com, pick any of the FBW Buses system manuals and download the Flight Controls chapter. Your questions will be answered in fairly good detail.
Only half a speed-brake
Hi AF330,
it works like this.
You fly level, with stick released, and set throttles to idle. The aircraft will start decelerating toward speed Valpha prot (the yellow band). At Vaprot the low speed protection activates, and in order not to go any slower, the aircraft will pitch down to maintain Vaprot.
If you then pull on the stick and raise the nose, the speed will decay down to V alpha max (the red band). This means you will override the AlphaProt logic and fly slower than V alpha prot. The aircraft will keep descending, as you do not have a sufficient thrust to maintain level flight, but at speed V aplha max.
Actually, no. Because you asked for the aircraft to go upwards with your side stick command, a few moments before reaching V alpha max the A/THR system will command full thrust, irrespective of throttle levers position. This is called the A.FLOOR function of the autothrust system. Unless it is disabled beforehand by a specific trick, it will give you full power from the engines anytime the speeds gets too low (just above Valpha max).
So, eventually you will be climbing after all, with TOGA thrust and at speed V alpha max - provided you keep pulling on the stick. If you release the stick then, your override of AlphaProt function will cease to exist, and the AlphaProt function will lower the nose just a little in order to accelerate twards Valphaprot (the top of yellow band). When Valpha prot is regained, with released stick the aircraft will keep this speed, whilst climbing. The climb is the result of excess energy provided by the TOGA thrust from the engines.
I know this does not really answer all the questions you asked, but I would like to suggest you digest the above first, before going any deeper.
Sounds good?
Cheers,
FD.
it works like this.
You fly level, with stick released, and set throttles to idle. The aircraft will start decelerating toward speed Valpha prot (the yellow band). At Vaprot the low speed protection activates, and in order not to go any slower, the aircraft will pitch down to maintain Vaprot.
If you then pull on the stick and raise the nose, the speed will decay down to V alpha max (the red band). This means you will override the AlphaProt logic and fly slower than V alpha prot. The aircraft will keep descending, as you do not have a sufficient thrust to maintain level flight, but at speed V aplha max.
Actually, no. Because you asked for the aircraft to go upwards with your side stick command, a few moments before reaching V alpha max the A/THR system will command full thrust, irrespective of throttle levers position. This is called the A.FLOOR function of the autothrust system. Unless it is disabled beforehand by a specific trick, it will give you full power from the engines anytime the speeds gets too low (just above Valpha max).
So, eventually you will be climbing after all, with TOGA thrust and at speed V alpha max - provided you keep pulling on the stick. If you release the stick then, your override of AlphaProt function will cease to exist, and the AlphaProt function will lower the nose just a little in order to accelerate twards Valphaprot (the top of yellow band). When Valpha prot is regained, with released stick the aircraft will keep this speed, whilst climbing. The climb is the result of excess energy provided by the TOGA thrust from the engines.
I know this does not really answer all the questions you asked, but I would like to suggest you digest the above first, before going any deeper.
Sounds good?
Cheers,
FD.
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Hi FlightDetent!
Thanks a lot for your great post! Yes, I had to read it 10 times to understand it! Yes, lot's of questions, like - I am sure- you had expected!
Well, this is what I have understood:
- When you are at level and you decrease the speed, if it reaches alpha protection, the plane will pitch down to get back speed.
QUESTIONS AT LEVEL
1) At which speed will it fly? The upper limit of Alpha protection?
2) But what if you had entered a speed in the FCU, and that speed was bellow VLS, will the plane maintain that speed or the alpha protection one?
3) The plane will go down, but what happens if you had your altitude managed?
4)Will "that" speed be managed by pitch?
- When you pull your stick, the plane will reach Alpha max, but Alpha floor will give max TOGA, till we leave the stick where alpha protection will pitch down and maintain the upper speed of alpha protection.
QUESTIONS GOING UP:
1) If we have climbed, I imagine that our altitude was not managed, or not even selected (open climb), the altitude function has disconnected, am I right? If yes, no questions about altitude!
1) Same question, will it maintain that speed by pitch?
2) What if we had entered a speed in the FCU? Will it still fly that one?
QUESTIONS WITH AN EXAMPLE
We are flying A320 and here are our waypoints:
-AGOPA: FL80- 220 knots
-LORNI: FL60- 210 knots
-MOPAR: FL50- 205 knots
-MANOX: FL30- 180 knots
We are at AGOPA, FL80 entered in the FCU, speed managed.
We forget do enter FL29 managed in the FCU, speed reaches 185 knots, and hits alpha protection and pitch goes down to regain speed...
1) At which speed will the plane fly?
2) Will it then leave our managed speed? Or still try to reach it?
3) At which altitude will it stabilize? Will it leave the managed altitude?
EXTRA QUESTIONS
I just would like a approximative number for these questions: (A320- A330)
1) What is generally a take-off angle?
2) A climb angle?
3) A cruise angle?
See what I read!
"Pitch during descent is only slighty negative e.g. at low altitude (e.g. 5000ft) at 64500kgs and 250kts the rate of descent is 1660ft/min which results in a pitch attitude of -0.6deg
At 214kts (approx green dot) the pitch attitude is +2.3deg during an idle descent!"
4) A descent angle?
5) After green dot angle?
6) Rotation altitude?
EXTRA QUESTIONS PART 2
1) Why during take-off the Alpha protection and alpha max is equal for 5 seconds?
QUESTION WITH A SADLY CRASH:
1) Why did AF447 stall? Didn't alpha floor react? Or was it too late?
Thanks a lot Flight Detent!
Thanks to clear me on these questions (very important for me!)...
With my kind regards,
AF330
Thanks a lot for your great post! Yes, I had to read it 10 times to understand it! Yes, lot's of questions, like - I am sure- you had expected!
Well, this is what I have understood:
- When you are at level and you decrease the speed, if it reaches alpha protection, the plane will pitch down to get back speed.
QUESTIONS AT LEVEL
1) At which speed will it fly? The upper limit of Alpha protection?
2) But what if you had entered a speed in the FCU, and that speed was bellow VLS, will the plane maintain that speed or the alpha protection one?
3) The plane will go down, but what happens if you had your altitude managed?
4)Will "that" speed be managed by pitch?
- When you pull your stick, the plane will reach Alpha max, but Alpha floor will give max TOGA, till we leave the stick where alpha protection will pitch down and maintain the upper speed of alpha protection.
QUESTIONS GOING UP:
1) If we have climbed, I imagine that our altitude was not managed, or not even selected (open climb), the altitude function has disconnected, am I right? If yes, no questions about altitude!
1) Same question, will it maintain that speed by pitch?
2) What if we had entered a speed in the FCU? Will it still fly that one?
QUESTIONS WITH AN EXAMPLE
We are flying A320 and here are our waypoints:
-AGOPA: FL80- 220 knots
-LORNI: FL60- 210 knots
-MOPAR: FL50- 205 knots
-MANOX: FL30- 180 knots
We are at AGOPA, FL80 entered in the FCU, speed managed.
We forget do enter FL29 managed in the FCU, speed reaches 185 knots, and hits alpha protection and pitch goes down to regain speed...
1) At which speed will the plane fly?
2) Will it then leave our managed speed? Or still try to reach it?
3) At which altitude will it stabilize? Will it leave the managed altitude?
EXTRA QUESTIONS
I just would like a approximative number for these questions: (A320- A330)
1) What is generally a take-off angle?
2) A climb angle?
3) A cruise angle?
See what I read!
"Pitch during descent is only slighty negative e.g. at low altitude (e.g. 5000ft) at 64500kgs and 250kts the rate of descent is 1660ft/min which results in a pitch attitude of -0.6deg
At 214kts (approx green dot) the pitch attitude is +2.3deg during an idle descent!"
4) A descent angle?
5) After green dot angle?
6) Rotation altitude?
EXTRA QUESTIONS PART 2
1) Why during take-off the Alpha protection and alpha max is equal for 5 seconds?
QUESTION WITH A SADLY CRASH:
1) Why did AF447 stall? Didn't alpha floor react? Or was it too late?
Thanks a lot Flight Detent!
Thanks to clear me on these questions (very important for me!)...
With my kind regards,
AF330
Only half a speed-brake
AF330,
I ommited one very important fact in the first post for you. Everything I tried to describe was for a situation, where the guidance (the flight director) is completely off. So no ALT mode, or selecting speed on FCU.
Cheers,
FD.
I ommited one very important fact in the first post for you. Everything I tried to describe was for a situation, where the guidance (the flight director) is completely off. So no ALT mode, or selecting speed on FCU.
Cheers,
FD.
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Yes you are right flight detent. But could you please give me an approximation for the angle? At which angle does alpha protection come, at which angle does alpha max come? Thanks and regards
Only half a speed-brake
Let me give a try. 
I may need to be quite picky with terminology, in order not to confuse one thing for another.
Rephrase needed: If you fly level and select thrust idle, the aircraft will initially maintain altitude but obviously deccelerate. Once the speed gets as low as V alpha prot (the top of the amber band), the alpha protection activates and will pitch nose down as necessary to maintain this Valphaprot.
1) Yes, see above.
2) Forget VLS this time, that's for Autothrust. We assume A/THR is off.
3) in my scenario, as the aircraft is not able to maintan level due too little thrust, the activation of alpha prot (nose down command) will disregardt the "ALT HOLD".
4) Yes, the aircraft will pitch up or down to maintaint V alphaprot.
Fair. Note that TOGA is commanded by the A.FLOOR feature, the max thrust will remain selected irrespective of stick position.
1) Your use of words "managed" and "selected" seem to indicate a different meaning to them compared to what I am used to. But my example assumes no altitude functions connected in a first place. 
1) Yes, the alpha prot function, unless overriden by push/pull on the stick, will always adjust pitch so that aircraft will not fly slower than Valpha prot (top of the amber band). This may cause increase of descent (e.g. with thrust at idle), or a reduction in climb (e.g. with TOGA). The resulting trajectory will always depend on how much thrust is available from the engines in any particular moment.
2) See above, FCU speed selection is for guidance modes of autopilot and/or autothrust. I assume none are used.
From my point of view, the example you give involves interaction of speed protection function with altitude guidance, speed orders and, more over, the flight navigation computer's vertical features. To explain properly, we'll end up writing full FCOM. I'll need to pass. 
Still
2) see above. The alpha prot will, at any time, reduce the pitch so that speed never goes below Valpha prot (top of amber band). Irrespective of any FCU or FMS settings. The only way to not pitch down is to pull on the stick, and override alpha prot. Then the speed would most likely drop all the way to V aplha max (top of the red band) at which point the alpha max protection will reduce the pitch to maintain V aplha max. This cannot be overriden.
3) Unless some action is taken, the unavoidable final altitude will be AGL=0. (joke, but true).
I assume by "angle" you mean pitch. My best guess for A320:
1) 13-18 deg nose up. Depends on speed / weight.
2) 3 to 12 deg nose up. Depends on speed / weight / altitude.
3) 1,5 to 3 deg nose up. Depends on speed / weight / altitude.
4) 3 deg up to 4 deg nose down. Depends on speed / weight / altitude.
5) Question not understood.
6) Likewise.
That is the way the software is designed. Probably to allow for dynamics of takeoff itself.
Very simplified: The sensors were providing erratic information. In such case, the protections were de-activated by internal logic.
Take care,
FD.
I may need to be quite picky with terminology, in order not to confuse one thing for another.
When you are at level and you decrease the speed, if it reaches alpha protection, the plane will pitch down to get back speed.
QUESTIONS AT LEVEL
1) At which speed will it fly? The upper limit of Alpha protection?
2) But what if you had entered a speed in the FCU, and that speed was bellow VLS, will the plane maintain that speed or the alpha protection one?
3) The plane will go down, but what happens if you had your altitude managed?
4)Will "that" speed be managed by pitch?
1) At which speed will it fly? The upper limit of Alpha protection?
2) But what if you had entered a speed in the FCU, and that speed was bellow VLS, will the plane maintain that speed or the alpha protection one?
3) The plane will go down, but what happens if you had your altitude managed?
4)Will "that" speed be managed by pitch?
2) Forget VLS this time, that's for Autothrust. We assume A/THR is off.
3) in my scenario, as the aircraft is not able to maintan level due too little thrust, the activation of alpha prot (nose down command) will disregardt the "ALT HOLD".
4) Yes, the aircraft will pitch up or down to maintaint V alphaprot.
- When you pull your stick, the plane will reach Alpha max, but Alpha floor will give max TOGA, till we leave the stick where alpha protection will pitch down and maintain the upper speed of alpha protection.
QUESTIONS GOING UP:
1) If we have climbed, I imagine that our altitude was not managed, or not even selected (open climb), the altitude function has disconnected, am I right? If yes, no questions about altitude!
1) Same question, will it maintain that speed by pitch?
2) What if we had entered a speed in the FCU? Will it still fly that one?
1) If we have climbed, I imagine that our altitude was not managed, or not even selected (open climb), the altitude function has disconnected, am I right? If yes, no questions about altitude!
1) Same question, will it maintain that speed by pitch?
2) What if we had entered a speed in the FCU? Will it still fly that one?
1) Yes, the alpha prot function, unless overriden by push/pull on the stick, will always adjust pitch so that aircraft will not fly slower than Valpha prot (top of the amber band). This may cause increase of descent (e.g. with thrust at idle), or a reduction in climb (e.g. with TOGA). The resulting trajectory will always depend on how much thrust is available from the engines in any particular moment.
2) See above, FCU speed selection is for guidance modes of autopilot and/or autothrust. I assume none are used.
QUESTIONS WITH AN EXAMPLE
We are flying A320 and here are our waypoints:
-AGOPA: FL80- 220 knots
-LORNI: FL60- 210 knots
-MOPAR: FL50- 205 knots
-MANOX: FL30- 180 knots
We are at AGOPA, FL80 entered in the FCU, speed managed.
We forget do enter FL29 managed in the FCU, speed reaches 185 knots, and hits alpha protection and pitch goes down to regain speed...
1) At which speed will the plane fly?
2) Will it then leave our managed speed? Or still try to reach it?
3) At which altitude will it stabilize? Will it leave the managed altitude?
We are flying A320 and here are our waypoints:
-AGOPA: FL80- 220 knots
-LORNI: FL60- 210 knots
-MOPAR: FL50- 205 knots
-MANOX: FL30- 180 knots
We are at AGOPA, FL80 entered in the FCU, speed managed.
We forget do enter FL29 managed in the FCU, speed reaches 185 knots, and hits alpha protection and pitch goes down to regain speed...
1) At which speed will the plane fly?
2) Will it then leave our managed speed? Or still try to reach it?
3) At which altitude will it stabilize? Will it leave the managed altitude?
Still
2) see above. The alpha prot will, at any time, reduce the pitch so that speed never goes below Valpha prot (top of amber band). Irrespective of any FCU or FMS settings. The only way to not pitch down is to pull on the stick, and override alpha prot. Then the speed would most likely drop all the way to V aplha max (top of the red band) at which point the alpha max protection will reduce the pitch to maintain V aplha max. This cannot be overriden.
3) Unless some action is taken, the unavoidable final altitude will be AGL=0. (joke, but true).
EXTRA QUESTIONS
I just would like a approximative number for these questions: (A320- A330)
1) What is generally a take-off angle?
2) A climb angle?
3) A cruise angle?
See what I read!
"Pitch during descent is only slighty negative e.g. at low altitude (e.g. 5000ft) at 64500kgs and 250kts the rate of descent is 1660ft/min which results in a pitch attitude of -0.6deg
At 214kts (approx green dot) the pitch attitude is +2.3deg during an idle descent!"
4) A descent angle?
5) After green dot angle?
6) Rotation altitude?
I just would like a approximative number for these questions: (A320- A330)
1) What is generally a take-off angle?
2) A climb angle?
3) A cruise angle?
See what I read!
"Pitch during descent is only slighty negative e.g. at low altitude (e.g. 5000ft) at 64500kgs and 250kts the rate of descent is 1660ft/min which results in a pitch attitude of -0.6deg
At 214kts (approx green dot) the pitch attitude is +2.3deg during an idle descent!"
4) A descent angle?
5) After green dot angle?
6) Rotation altitude?
1) 13-18 deg nose up. Depends on speed / weight.
2) 3 to 12 deg nose up. Depends on speed / weight / altitude.
3) 1,5 to 3 deg nose up. Depends on speed / weight / altitude.
4) 3 deg up to 4 deg nose down. Depends on speed / weight / altitude.
5) Question not understood.
6) Likewise.
EXTRA QUESTIONS PART 2
1) Why during take-off the Alpha protection and alpha max is equal for 5 seconds?
1) Why during take-off the Alpha protection and alpha max is equal for 5 seconds?
QUESTION WITH A SADLY CRASH:
1) Why did AF447 stall? Didn't alpha floor react? Or was it too late?
1) Why did AF447 stall? Didn't alpha floor react? Or was it too late?
Take care,
FD.
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Oh!!!! Great!!!!!!!!! Thanks a lot Flight Detent!!!!! You are simply great!!!!!!!
I thought that when someone will read the size of my question, he won't even try to answer it!!!!!!!
Ok, less questions this time! But I am really getting it...
1) Is all the alpha stuff related to AoA or pitch?
2) What is the difference between pitch and AoA?
3) Could you just answer my question with angles with the AoA?
I had read something with 33 degrees, 45 degrees...
At what angle (pitch and AoA if possible!) does alpha protection come? alpha max?
4) Will that alpha protection speed controlled by our last lever position? (I don't think it will control it with TOGA!!!!) maybe climb ( if we were in A/THR) or IDLE...
5) Ok so basically you have to do something, and to remove alpha protection, or you put back the autopilot and everything in managed mode (so no problem!) or you try to take speed (pitch down or throttle..)
Thanks a lot Flight Detent! You really have helped me! Once again:
THANK YOU!
Take care,
With my kind regards,
AF330
I thought that when someone will read the size of my question, he won't even try to answer it!!!!!!!
Ok, less questions this time! But I am really getting it...
1) Is all the alpha stuff related to AoA or pitch?
2) What is the difference between pitch and AoA?
3) Could you just answer my question with angles with the AoA?
I had read something with 33 degrees, 45 degrees...
At what angle (pitch and AoA if possible!) does alpha protection come? alpha max?
4) Will that alpha protection speed controlled by our last lever position? (I don't think it will control it with TOGA!!!!) maybe climb ( if we were in A/THR) or IDLE...
5) Ok so basically you have to do something, and to remove alpha protection, or you put back the autopilot and everything in managed mode (so no problem!) or you try to take speed (pitch down or throttle..)
Thanks a lot Flight Detent! You really have helped me! Once again:
THANK YOU!
Take care,
With my kind regards,
AF330
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Thanks yardman...
1) So is the AoA between the chord line and the relative wind?
2) So I imagine that the alpha stuff is related to AoA...
3) But I just saw a video where they had reached alpha max and TOGA THRUST came, and brought them at 220 knots and then the video finished. But will the plane go to alpha protection speed by pitch? Well it's what I thought...
4) Is that speed, i imagine the alpha protection one, controlled by our last lever position (with pitch of course...)?
5) To remove alpha protection, you need to take speed by yourself, am I right?
6) Could you please give me the angles for AoA, and at which angle does alpha protection and max happen? ( pitch and AoA, if possible!)
Thanks a lot Flight detent and yardman!
1) So is the AoA between the chord line and the relative wind?
2) So I imagine that the alpha stuff is related to AoA...
3) But I just saw a video where they had reached alpha max and TOGA THRUST came, and brought them at 220 knots and then the video finished. But will the plane go to alpha protection speed by pitch? Well it's what I thought...
4) Is that speed, i imagine the alpha protection one, controlled by our last lever position (with pitch of course...)?
5) To remove alpha protection, you need to take speed by yourself, am I right?
6) Could you please give me the angles for AoA, and at which angle does alpha protection and max happen? ( pitch and AoA, if possible!)
Thanks a lot Flight detent and yardman!
Only half a speed-brake
FCOM:
Alpha-floor protection automatically sets the thrust at TOGA thrust, when the aircraft reaches a very high angle of attack.
The Flight Augmentation Computer (FAC) generates the signal that triggers the alpha-floor mode. This, in turn, sets TOGA thrust on the engines, regardless of the thrust lever positions (Refer to DSC-22_30-90 A/THR Modes - General).
The FAC sends this signal when:
‐ The angle of attack is above a predetermined threshold, that is a function of the configuration.
Alpha-floor protection automatically sets the thrust at TOGA thrust, when the aircraft reaches a very high angle of attack.
The Flight Augmentation Computer (FAC) generates the signal that triggers the alpha-floor mode. This, in turn, sets TOGA thrust on the engines, regardless of the thrust lever positions (Refer to DSC-22_30-90 A/THR Modes - General).
The FAC sends this signal when:
‐ The angle of attack is above a predetermined threshold, that is a function of the configuration.
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Once again, thanks Flight Detent!
But I think that I have understood that part...
Ok, let me explain myself:
We have our thrust IDLE, autopilot off, we reach alpha protection, and the plane pitches to maintain the alpha protection speed. But then we pull on the stick and the plane reaches alpha max, and alpha floor gives you full TOGA thrust. We release the stick and the plane stops at 220 knots, it then goes back to alpha protection speed, by the speed controlled by thrust. Then it maintains that by pitch.
1) Am I right till here?
Well, I hope...
My question, with which thrust levers is the alpha protection speed controlled with pitch? Is it IDLE, because we were in IDLE?
Same question:
We have our thrust CLIMB, autopilot off, we reach alpha protection, and the plane pitches to maintain the alpha protection speed. But then we pull on the stick and the plane reaches alpha max, and alpha floor gives you full TOGA thrust. We release the stick and the plane stops at 220 knots, it then goes back to alpha protection speed, by the speed controlled by thrust. Then it maintains that by pitch. My question, with which thrust levers is the alpha protection speed controlled with pitch? Is it CLIMB, because we were in CLIMB?
PS: Could anyone give me the angles at AoA? Rotation, climb, cruise, descent, alpha prot, alpha max...
Thanks a lot,
AF330
But I think that I have understood that part...
Ok, let me explain myself:
We have our thrust IDLE, autopilot off, we reach alpha protection, and the plane pitches to maintain the alpha protection speed. But then we pull on the stick and the plane reaches alpha max, and alpha floor gives you full TOGA thrust. We release the stick and the plane stops at 220 knots, it then goes back to alpha protection speed, by the speed controlled by thrust. Then it maintains that by pitch.
1) Am I right till here?
Well, I hope...
My question, with which thrust levers is the alpha protection speed controlled with pitch? Is it IDLE, because we were in IDLE?
Same question:
We have our thrust CLIMB, autopilot off, we reach alpha protection, and the plane pitches to maintain the alpha protection speed. But then we pull on the stick and the plane reaches alpha max, and alpha floor gives you full TOGA thrust. We release the stick and the plane stops at 220 knots, it then goes back to alpha protection speed, by the speed controlled by thrust. Then it maintains that by pitch. My question, with which thrust levers is the alpha protection speed controlled with pitch? Is it CLIMB, because we were in CLIMB?
PS: Could anyone give me the angles at AoA? Rotation, climb, cruise, descent, alpha prot, alpha max...
Thanks a lot,
AF330
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Well, let's say that I want to know which amount of thrust will be given? If our thrust levers WERE in IDLE, will it give IDLE thrust and maintain tge alpha protection speed with thrust IDLE+ pitch. Am I right?
Thanks
Thanks
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Ok, I have more or less got the concept. But could anyone give me this answer:
Alpha floor speed= alpha protection-.....knots.
So it will give alpha protection is from a "speed" to .....knots after that speed, alpha floor gives you TOGA thrust.
PS: for A320- A330
Thanks
Alpha floor speed= alpha protection-.....knots.
So it will give alpha protection is from a "speed" to .....knots after that speed, alpha floor gives you TOGA thrust.
PS: for A320- A330
Thanks
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Hi FD,
You had said that at Vprot, the plane pitches down and maintains Vprot.
Vfloor is a function of A/THR. A/THR will never go below VLS.
So what is maintaining Vprot? Or does it simply pitch down to take back speed (and doesn't manage Vprot).
Or do the FAC send signals to the FADEC system and the other F-CTL? Does it manage Vprot by speed mode or thrust mode?
Thanks
You had said that at Vprot, the plane pitches down and maintains Vprot.
Vfloor is a function of A/THR. A/THR will never go below VLS.
So what is maintaining Vprot? Or does it simply pitch down to take back speed (and doesn't manage Vprot).
Or do the FAC send signals to the FADEC system and the other F-CTL? Does it manage Vprot by speed mode or thrust mode?
Thanks
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It might help you to think of the thrust and pitch separately.
1)with low thrust, you let speed decay to Vprot. Then aircraft pitches down to maintain Vprot. Then you pull stick back and it allows you to go to V.a.max, but no lower. You release the stick again and it pitches down to accelerate to and maintain Vprot.
2) At some stage between Vprot and V.a.max, you get A.floor. This only does one thing. Orders TOGA from the engines which remains until you remove the thrust lock by pushing the instinctive disconnect. The position of the levers has no effect on the thrust at this stage. Even if you move them up and down, the thrust from the engines is locked at TOGA. This is not an autothrust function and there is no speed mode.
1)with low thrust, you let speed decay to Vprot. Then aircraft pitches down to maintain Vprot. Then you pull stick back and it allows you to go to V.a.max, but no lower. You release the stick again and it pitches down to accelerate to and maintain Vprot.
2) At some stage between Vprot and V.a.max, you get A.floor. This only does one thing. Orders TOGA from the engines which remains until you remove the thrust lock by pushing the instinctive disconnect. The position of the levers has no effect on the thrust at this stage. Even if you move them up and down, the thrust from the engines is locked at TOGA. This is not an autothrust function and there is no speed mode.
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Thanks a lot!
So to maintain Vprot, FAC's send signals to the other F-CTL (to pitch down....etc) and also directly to FADEC? FAC's will basically do what A/THR does?
I understood your thing. But you say "to maintain Vprot"
When the plane pitches down, it can take speed. So if it is maintaining Vprot, something has to command.
So what is controlling speed at Vprot?
Thanks
So to maintain Vprot, FAC's send signals to the other F-CTL (to pitch down....etc) and also directly to FADEC? FAC's will basically do what A/THR does?
I understood your thing. But you say "to maintain Vprot"
When the plane pitches down, it can take speed. So if it is maintaining Vprot, something has to command.
So what is controlling speed at Vprot?
Thanks
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at the stage it is maintaining vprot, it will do so by pushing nose down. This function is commanded by whichever computer is controlling the elevators and THS (Normally ELAC2 but redundency provided by ELAC1, SEC2, SEC1). As soon as there is enough thrust to exceed V.prot, it will maintain 1G as it is still in normal law... where zero sidestick commands 1G. this means if you get A.floor and leave the stick alone, you will accelerate (Rapidly) while maintaining 1G (and a level or slightly nose down attitude i imagine)
the FAC (there are 2 of them) monitors angle of attack and simply sends the message for TOGA... not sure if it sends it directly to the FADECs or through some intermediary...
If you maintain full back stick with A.floor, the plane will use pitch (Commanded by ELAC2) to keep V.a.max, pulling the nose up just as much as it can without letting the speed drop below V.a.max. The plane then climbs like a homesick angel.
The thrust is commanded to TOGA by the A.floor function of the FACs... when you are no longer in A.floor, this changes to TOGA LOCK... the only difference between the two is that you can get out of TOGA LOCK by pushing the instinctive disconnect, then take back manual control of the thrust, and re engage autothrust if you so desire In A.FLOOR you cannot get out of TOGA until the conditions (AoA) are no longer met for A.floor.
complicated i know....
the FAC (there are 2 of them) monitors angle of attack and simply sends the message for TOGA... not sure if it sends it directly to the FADECs or through some intermediary...
If you maintain full back stick with A.floor, the plane will use pitch (Commanded by ELAC2) to keep V.a.max, pulling the nose up just as much as it can without letting the speed drop below V.a.max. The plane then climbs like a homesick angel.
The thrust is commanded to TOGA by the A.floor function of the FACs... when you are no longer in A.floor, this changes to TOGA LOCK... the only difference between the two is that you can get out of TOGA LOCK by pushing the instinctive disconnect, then take back manual control of the thrust, and re engage autothrust if you so desire In A.FLOOR you cannot get out of TOGA until the conditions (AoA) are no longer met for A.floor.
complicated i know....
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Thanks,
1) Didn't reaaly get the 1G thing, could you explain please?
2) Ok, so Vprot is managed by ELAC. They know Vprot, they know the plane's IAS. Am I right or is it the FAC's who send signals of pitch to ELAc's?
It would mean that FAC's know Vprot, the IAS of the plane and it's attitude. It can then send signals of pitch to ELAC's
3) Ok Vfloor = managed by FAC's
Right?
4) TOGA LOCK = Given by A/THR
So once outside Alpha floor range, FAC's send signals to A/THR to give TOGA
Right?
Thanks
1) Didn't reaaly get the 1G thing, could you explain please?
2) Ok, so Vprot is managed by ELAC. They know Vprot, they know the plane's IAS. Am I right or is it the FAC's who send signals of pitch to ELAc's?
It would mean that FAC's know Vprot, the IAS of the plane and it's attitude. It can then send signals of pitch to ELAC's
3) Ok Vfloor = managed by FAC's
Right?
4) TOGA LOCK = Given by A/THR
So once outside Alpha floor range, FAC's send signals to A/THR to give TOGA
Right?
Thanks