A/T: is it really helping you ?
Joined: Feb 2003
Posts: 541
Likes: 336
From: Blue sky
Because stability is used as excuse to claim it is "harder" to fly with A/T on than with A/T off.
If the AP would create such a situation in which it's trim speed would be "stuck", fine, I'll join you in the room to debate with the engineers behind the desks and hit the engineer button. In the 6 years experienced on the 777 I have never ever even touched the alternate pitch trim levers. I can't even recall if any checklist refers to the use of these levers.
We are pilots. From a pilot training perspective stability has never been the problem in the original question as you can perfectly trim out the aircraft. A pilot with average flying skills will not even notice. Stability is a false excuse. Out-of-trim is the problem, and any pilot can easily solve that. You just have to set the "setpoints" equal to use your terms.
If the AP would create such a situation in which it's trim speed would be "stuck", fine, I'll join you in the room to debate with the engineers behind the desks and hit the engineer button. In the 6 years experienced on the 777 I have never ever even touched the alternate pitch trim levers. I can't even recall if any checklist refers to the use of these levers.
We are pilots. From a pilot training perspective stability has never been the problem in the original question as you can perfectly trim out the aircraft. A pilot with average flying skills will not even notice. Stability is a false excuse. Out-of-trim is the problem, and any pilot can easily solve that. You just have to set the "setpoints" equal to use your terms.
Joined: Sep 2016
Posts: 936
Likes: 67
From: USA
Joined: Feb 2003
Posts: 541
Likes: 336
From: Blue sky
It’s only unstable in a failure case with a stuck trim reference speed for me as a pilot. Which never has happened as far as I know. The alternate trim levers are useless. My engineering thinking stayed on the ground pre 2000. The effect is unnoticeable.
And again... don’t blame the A/T is making it more difficult, you have to trim properly. That’s it and that’s easy.
And again... don’t blame the A/T is making it more difficult, you have to trim properly. That’s it and that’s easy.
Last edited by BraceBrace; 19th June 2024 at 22:14.
Thread Starter
Joined: Apr 2022
Posts: 267
Likes: 21
From: France
Because it is true. That's not insulting, it's a reality.
I'll reply one last time, because I must have read the original question 20 times... I still don't get it. This is the world upside down.
This is the situation that happens so many times in training or during line checks, where something doesn't really quite works because of a skillset that lacks. However, because the automation was unable to solve it, the crewmember ends up blaming automation for the lack of skillset.
.
I will leave it at that and stay out of the thread, nothing against you, I prefer beers at the bar. I'll take A/T off approaches any time weather permitting up to a certain level, don't worry, but the A/T is a consistent reliable system. No man's/woman's brain is. There is always a lapse, a miss, ... and a chase to get back on whatever parameter we ended up missing/chasing.
I'll reply one last time, because I must have read the original question 20 times... I still don't get it. This is the world upside down.
This is the situation that happens so many times in training or during line checks, where something doesn't really quite works because of a skillset that lacks. However, because the automation was unable to solve it, the crewmember ends up blaming automation for the lack of skillset.
.
I will leave it at that and stay out of the thread, nothing against you, I prefer beers at the bar. I'll take A/T off approaches any time weather permitting up to a certain level, don't worry, but the A/T is a consistent reliable system. No man's/woman's brain is. There is always a lapse, a miss, ... and a chase to get back on whatever parameter we ended up missing/chasing.
This topic is not a pilot's topic. It's an airplane design engineer's topic. Maybe that can clarify.
It's not a practical discussion. It's a philosophical one. My hand flying skills have nothing to do with it.
Is that better? Either you restore the in-trim situation, or if you can't, you can hope the AP can do it (within limits). It's called aircraft control
(Yes, this is a "reductio ad absurdum" reasoning")
If you want, we can make a diagram of the B777 throttle stability.
You can create a diagram of potential for every different value of (trim speed - speed bug).
If the difference is 0 knots, then the curve is convex, centered on the equilibrium thrust.
If the difference is positive, the curve is increasing, meaning there is an equilibrium thrust at idle.
If the difference is negative, the curve is decreasing, meaning there is an equilibrium thrust at toga.
The B777 throttle is stable if and only if there is no difference between speed bug and trim speed.
And a 1 knot difference is enough to change the curve from stable to unstable.
To build up on that, yes, you can very easily trim the airplane at a stable speed, thanks to the "clic clic" function or whatever the name of this undocumented but crucial function.
But what about times when you're not going to be in trim ? For example if you're reducing speed, you're not going to be in trim for a few seconds. The time it takes to trim. During this time your workload is uselessly increased. Let's say you're established on the ILS, and reducing speed. You ask the PM to reduce the speed bug. The airplane wants to dive. At this time, there is no simple way to keep a constant flight path. You're going to have to increase progressively your pitch, and increase progressively the stick force (except when you will start trimming, you will have to adapt the force).. Then let's say you properly managed to reach Vref+15 like so and everything's going well for now. You trim your airplane at Vref+10, while the airplane is slowing at Vref+5. Only 5 knots difference won't be very noticeable while you're still in speed reduction. Let's say you let the out of trim situation develop for 5 seconds. No effects are visible for now because they are exponential, so very little at first and much larger a few seconds later.
Then the PM asks you to complete the landing checklist or whatever other disturbance. Now if you wait 5 seconds more your engines can already be at idle.
An airplane that can go by itself from normal flight path to idle is less safe and more difficult to fly than an airplane that has a natural path stability.
I really don't see how anyone could claim the contrary.
Joined: Sep 2016
Posts: 936
Likes: 67
From: USA
*I can, only a little bit. My only plane with autothrottles is the 737, and I have only ever turned the AP and AT off at the same time. But some captains will leave the AT on for a little while before turning them off, and I don't see anything weird going on during that time.
Joined: Mar 2002
Aviation Qualifications: ATPL
Posts: 9,203
Likes: 966
From: Seat 1A
Originally Posted by CVividasku
An airplane that can go by itself from normal flight path to idle is less safe and more difficult to fly than an airplane that has a natural path stability.
I really don't see how anyone could claim the contrary.
I really don't see how anyone could claim the contrary.
You seriously need to either just fly the aeroplane like real pilots do or change jobs. You're holding on too tight.
Joined: Feb 2003
Posts: 541
Likes: 336
From: Blue sky
Yes, you really don't understand the goal of this topic.
This topic is not a pilot's topic. It's an airplane design engineer's topic. Maybe that can clarify.
It's not a practical discussion. It's a philosophical one. My hand flying skills have nothing to do with it.
...
For example if you're reducing speed, you're not going to be in trim for a few seconds. The time it takes to trim. During this time your workload is uselessly increased.
This topic is not a pilot's topic. It's an airplane design engineer's topic. Maybe that can clarify.
It's not a practical discussion. It's a philosophical one. My hand flying skills have nothing to do with it.
...
For example if you're reducing speed, you're not going to be in trim for a few seconds. The time it takes to trim. During this time your workload is uselessly increased.
You ask the questions at pilots, not engineers, and the question is litererally "is it really helping you?" Flightdeck answer: "we don't feel it" (and the engineers will proudly whisper "we got that nicely covered from those dumb pilots... let's drink beers as well"). Everybody happy.
Flying is a learned behaviour. If you stop flying, you die. In multiple possible ways. Valid for the Airbus as well. What you do is academic re-thinking what the world knows already, and Boeing covered in an economic acceptable way. It’s a nice case study at the university :-).
Last edited by BraceBrace; 20th June 2024 at 20:52.
Joined: Nov 1999
Aviation Qualifications: ATPL
Posts: 3,144
Likes: 741
From: UK
I have read the OP again and I really don't understand what CV is talking about:
my bold
You seem to be suggesting that auto-thrust looks at the TRS/THS speed and compares that with the IAS ? Which auto-thrust systems look at TRS/THS ? I have flown both B737 and Airbus FBW on the line and their auto-throttle/auto-thrust both respond to IAS.
In both aircraft types: if the IAS changes, the trim will change and either the pilot, the auto-pilot or the FBW will adjust the pitch trim, depending on type and whether they are flying manually or automatically. What's the problem ?
Why would the auto-thrust keep reducing thrust when aircraft speed is below the IAS speed bug, and "crash the plane", or "trigger a GPWS warning", or end "in deep trouble", in your words ????
Auto-thrust looks at IAS, not the TRS/THS, so why would the auto-thrust keep reducing thrust when the aircraft IAS is below the IAS speed bug ? Does the B777 do this differently ?
Or are you talking about Boeing Auto-throttle systems dropping out of active mode without warning and without the pilots noticing, as in the SFO B777 crash ?
Now let's suppose you have an A/T engaged.
You have a speed bug. At first you stabilize the airplane in level flight. Perfectly trimmed. So TRS = speed bug. Let's create a gap between the TRS and the speed bug. You can trim down, but since not many planes show the TRS, let's reduce the speed bug, this will allow us to make a small reduction that we can measure. Let's say a few knots. 5 knots. How much time have you got until you're in deep trouble ?
At first, almost nothing happens, and the instructor in the sim wonders why you asked to do this weird exercise.
There is only a 5kt difference so the A/T slowly reduces thrust, the speed reduces slowly too, it reduces even more slowly because the airplane is trimmed to keep its current speed at TRS. But the A/T continues to see a speed difference and continues to reduce thrust. Soon, the airplane behavior becomes exponential.
In a time that I could not evaluate in all configurations, and that is quicker if the speed difference is higher, but in any case much quicker than you would imagine, your airplane is stabilized in a descent with idle thrust. If you were on approach, in less than 30 seconds you end up with idle thrust and terrain warning to pull up.
You have a speed bug. At first you stabilize the airplane in level flight. Perfectly trimmed. So TRS = speed bug. Let's create a gap between the TRS and the speed bug. You can trim down, but since not many planes show the TRS, let's reduce the speed bug, this will allow us to make a small reduction that we can measure. Let's say a few knots. 5 knots. How much time have you got until you're in deep trouble ?
At first, almost nothing happens, and the instructor in the sim wonders why you asked to do this weird exercise.
There is only a 5kt difference so the A/T slowly reduces thrust, the speed reduces slowly too, it reduces even more slowly because the airplane is trimmed to keep its current speed at TRS. But the A/T continues to see a speed difference and continues to reduce thrust. Soon, the airplane behavior becomes exponential.
In a time that I could not evaluate in all configurations, and that is quicker if the speed difference is higher, but in any case much quicker than you would imagine, your airplane is stabilized in a descent with idle thrust. If you were on approach, in less than 30 seconds you end up with idle thrust and terrain warning to pull up.
my bold
You seem to be suggesting that auto-thrust looks at the TRS/THS speed and compares that with the IAS ? Which auto-thrust systems look at TRS/THS ? I have flown both B737 and Airbus FBW on the line and their auto-throttle/auto-thrust both respond to IAS.
In both aircraft types: if the IAS changes, the trim will change and either the pilot, the auto-pilot or the FBW will adjust the pitch trim, depending on type and whether they are flying manually or automatically. What's the problem ?
Why would the auto-thrust keep reducing thrust when aircraft speed is below the IAS speed bug, and "crash the plane", or "trigger a GPWS warning", or end "in deep trouble", in your words ????
Auto-thrust looks at IAS, not the TRS/THS, so why would the auto-thrust keep reducing thrust when the aircraft IAS is below the IAS speed bug ? Does the B777 do this differently ?
Or are you talking about Boeing Auto-throttle systems dropping out of active mode without warning and without the pilots noticing, as in the SFO B777 crash ?
Joined: Dec 2003
Posts: 2,343
Likes: 822
From: Tring, UK
I think what he is pointing out is that if you trim for a greater speed than you have bugged on a Boeing with autothrottle (and this would have the same effect in a non-FBW aircraft of any type), then let go of the controls, it will fly the trimmed speed and the A/T will take power off as it “sees” that the speed is in excess of what you have commanded.
What others in this thread have been saying is that this is a feature, not a bug. If you push forward and accelerate past the bug speed, the same thing will happen - why would you want the thrust to stay up and drive you towards limiting speeds? The assumption is that if you are flying manually, you are in control of the pitch and have put it where you want. Also, that the AFDS has been correctly programmed and you are satisfying FD commands or have switched them off.
The advantage of a C*U implementation is that even if you’re mostly focussed outside, you will get an indication of speed and speed trends from the control loadings, e.g. if you find you need back pressure to maintain the attitude you want, you know the speed has reduced before you even scan it, much in the way of a conventional aircraft. Although the aircraft does indeed do what was observed in the sim, it is only doing what you asked it to while replicating the behaviour of non-FBW aircraft, so it shouldn’t really come as a surprise?
What others in this thread have been saying is that this is a feature, not a bug. If you push forward and accelerate past the bug speed, the same thing will happen - why would you want the thrust to stay up and drive you towards limiting speeds? The assumption is that if you are flying manually, you are in control of the pitch and have put it where you want. Also, that the AFDS has been correctly programmed and you are satisfying FD commands or have switched them off.
The advantage of a C*U implementation is that even if you’re mostly focussed outside, you will get an indication of speed and speed trends from the control loadings, e.g. if you find you need back pressure to maintain the attitude you want, you know the speed has reduced before you even scan it, much in the way of a conventional aircraft. Although the aircraft does indeed do what was observed in the sim, it is only doing what you asked it to while replicating the behaviour of non-FBW aircraft, so it shouldn’t really come as a surprise?
Last edited by FullWings; 21st June 2024 at 09:30.
Thread Starter
Joined: Apr 2022
Posts: 267
Likes: 21
From: France
Yes, indeed Fullwings, thank you.
It shouldn't be coming as a surprise, however very few pilots can guess what happens when you describe the scenario. Most will correctly guess that the aircraft descends, but a large part incorrectly talk about the onset of a phugoid, and very few find the conclusion of the scenario, which is thrust being idle, even with guidance.
It's because it's actually not so intuitive that a 3 knot difference would lead the A/T to go to idle.
However, the explanation is that there must be an "integrating filter" in the A/T automatics that sense the speed difference building up over time and reducing to idle in reaction to it.
You get an indication of your speed from the control loadings, but you have no indication about your flight path, or the real energy of the aircraft.
If you want an indication of aircraft energy you have to look at thrust. Which is far to the left in your visual circuit*.
I find it personnally easier to set a fixed amount of thrust according to the flight phase, then only have to look at my speed, which is very much in the center of my visual circuit.
This works because I'm keen on understanding how much thrust is exactly required. I studied the airspeed unreliable tables to make sense out of them, I often look at which angle of glide I get from idle, and what's the power setting for my flight phase.
*On the other hand, the advantage of boeing is that you can also rely on your hand to get an indication of thrust.
It shouldn't be coming as a surprise, however very few pilots can guess what happens when you describe the scenario. Most will correctly guess that the aircraft descends, but a large part incorrectly talk about the onset of a phugoid, and very few find the conclusion of the scenario, which is thrust being idle, even with guidance.
It's because it's actually not so intuitive that a 3 knot difference would lead the A/T to go to idle.
However, the explanation is that there must be an "integrating filter" in the A/T automatics that sense the speed difference building up over time and reducing to idle in reaction to it.
You get an indication of your speed from the control loadings, but you have no indication about your flight path, or the real energy of the aircraft.
If you want an indication of aircraft energy you have to look at thrust. Which is far to the left in your visual circuit*.
I find it personnally easier to set a fixed amount of thrust according to the flight phase, then only have to look at my speed, which is very much in the center of my visual circuit.
This works because I'm keen on understanding how much thrust is exactly required. I studied the airspeed unreliable tables to make sense out of them, I often look at which angle of glide I get from idle, and what's the power setting for my flight phase.
*On the other hand, the advantage of boeing is that you can also rely on your hand to get an indication of thrust.
Joined: Sep 2016
Posts: 936
Likes: 67
From: USA
It reduces thrust because speed is *above* the speed bug, because trim speed is above the speed bug.
Joined: Nov 1999
Aviation Qualifications: ATPL
Posts: 3,144
Likes: 741
From: UK
I think the OP question is largely irrelevant, because professional, trained pilots will trim before the OP example will happen. Pilots in aircraft where manual trim is required will do so subconsciously and 'automatically'. If a pilot needs to trim, they will do so and not let a distraction stop them. If PM wants to read a checklist for example while PF is busy, PF simply says "standby".
Despite Boeing saying not to have auto-throttle active when flying a B737 manually, you can do it - I have done it - because when the auto-throttle increases or decreases, you simply adjust the pressure on your yoke to compensate for the pitch-power couple and then re-trim. The reason they say not to fly this way is that the auto-throttle can change 'without warning' so if you miss it, your flight path will change. However, if you are paying attention, you will see the changing parameters and adjust. Not recommended though.
It's like driving a manual car. You don't (I don't) consciously think about changing gear, your brain subconsciously notes the change of slope or speed or engine sound, and changes gear without you really thinking about it.
Manually trimming an aircraft is similar. You have to pay attention to the pitch, roll, flight path, and air speed, but the manual trimming happens in the background of your brain.
I personally don't like having to manually trim, or pitch-power couples, even though I flew many types on the line with manual trim, and it was an easy and 'automatic' process. I much prefer the Airbus FBW system which designs-out this shortcoming of previous (lack of) technology. (The only time I flew a B777 was a SIM, and the clic clic trim thing did not work - in fact the manual pitch trim did not work at all).
The OP's stated problem does not really exist in practice with professional pilots, because if it did, there would be weekly AAIB reports of non-FBW aircraft going out of control.
Despite Boeing saying not to have auto-throttle active when flying a B737 manually, you can do it - I have done it - because when the auto-throttle increases or decreases, you simply adjust the pressure on your yoke to compensate for the pitch-power couple and then re-trim. The reason they say not to fly this way is that the auto-throttle can change 'without warning' so if you miss it, your flight path will change. However, if you are paying attention, you will see the changing parameters and adjust. Not recommended though.
It's like driving a manual car. You don't (I don't) consciously think about changing gear, your brain subconsciously notes the change of slope or speed or engine sound, and changes gear without you really thinking about it.
Manually trimming an aircraft is similar. You have to pay attention to the pitch, roll, flight path, and air speed, but the manual trimming happens in the background of your brain.
I personally don't like having to manually trim, or pitch-power couples, even though I flew many types on the line with manual trim, and it was an easy and 'automatic' process. I much prefer the Airbus FBW system which designs-out this shortcoming of previous (lack of) technology. (The only time I flew a B777 was a SIM, and the clic clic trim thing did not work - in fact the manual pitch trim did not work at all).
The OP's stated problem does not really exist in practice with professional pilots, because if it did, there would be weekly AAIB reports of non-FBW aircraft going out of control.
Thread Starter
Joined: Apr 2022
Posts: 267
Likes: 21
From: France
I flew today my first AT OFF approach, the least I can say is that it was much easier than with it turned on.
Not only for the reasons listed above in this topic. Maybe the main reason was more related with the AT itself. On most of my previous approaches, it was commanding too much thrust during speed reduction, leading to a longer delay between platform speed and Vapp.
There were some gusts and up/downdrafts, keeping a constant thrust made managing the entire thing easier in my opinion. The speed varied within +/- 2 to 3 kt yes but the trajectory was the best I performed in my short experience so far on this plane.
It does happen sometimes... I chatted with my instructor who described having seen pilots with catastrophic hand flying skills.
I also saw that for myself, when I was in training a few years ago, the school used to host airline evaluation sessions in their sims. One of the instructor showed me the plots for a few approaches of the preceding week. Out of 20 candidates, more than 3 had crashed the plane, during a normal ILS approach in IMC with no failure.
These were obviously not hired, and I hope nobody hired them since. But if they managed to get through somehow, somewhere, this is precisely the type of pilot that would get tricked by this kind of behavior. They probably got tricked by exactly that one in that sim. The descent was idle to the ground.
Has anyone got any knowledge about the A220 ?
A friend told me that it displayed the TRS, and that the speed bug could move by itself, and that it was recommended or mandatory to synchronise the TRS with the speed bug.
If yes, it's a bit stupid. For example, on an airbus 320, if you want to accelerate from V2+15 to 250kt, you just slightly push the stick.
On the B777 you have to trim all the way, but increase the speed bug only once.
On the A220, possibly you would have to trim all the way, but also increase the speed bug in steps. That would be multiplying the number of actions to do.
Not only for the reasons listed above in this topic. Maybe the main reason was more related with the AT itself. On most of my previous approaches, it was commanding too much thrust during speed reduction, leading to a longer delay between platform speed and Vapp.
There were some gusts and up/downdrafts, keeping a constant thrust made managing the entire thing easier in my opinion. The speed varied within +/- 2 to 3 kt yes but the trajectory was the best I performed in my short experience so far on this plane.
The OP's stated problem does not really exist in practice with professional pilots, because if it did, there would be weekly AAIB reports of non-FBW aircraft going out of control.
I also saw that for myself, when I was in training a few years ago, the school used to host airline evaluation sessions in their sims. One of the instructor showed me the plots for a few approaches of the preceding week. Out of 20 candidates, more than 3 had crashed the plane, during a normal ILS approach in IMC with no failure.
These were obviously not hired, and I hope nobody hired them since. But if they managed to get through somehow, somewhere, this is precisely the type of pilot that would get tricked by this kind of behavior. They probably got tricked by exactly that one in that sim. The descent was idle to the ground.
Has anyone got any knowledge about the A220 ?
A friend told me that it displayed the TRS, and that the speed bug could move by itself, and that it was recommended or mandatory to synchronise the TRS with the speed bug.
If yes, it's a bit stupid. For example, on an airbus 320, if you want to accelerate from V2+15 to 250kt, you just slightly push the stick.
On the B777 you have to trim all the way, but increase the speed bug only once.
On the A220, possibly you would have to trim all the way, but also increase the speed bug in steps. That would be multiplying the number of actions to do.
Joined: Mar 2002
Aviation Qualifications: ATPL
Posts: 9,203
Likes: 966
From: Seat 1A
Originally Posted by CVid...
I flew today my first AT OFF approach, the least I can say is that it was much easier than with it turned on.
The speed varied within +/- 2 to 3 kt yes but the trajectory was the best I performed in my short experience so far on this plane.
Out of interest, what "plane" are you flying?
Has anyone got any knowledge about the A220 ?
A friend told me that it displayed the TRS, and that the speed bug could move by itself, and that it was recommended or mandatory to synchronise the TRS with the speed bug.
If yes, it's a bit stupid.
On the A220, possibly you would have to trim all the way, but also increase the speed bug in steps. That would be multiplying the number of actions to do.
A friend told me that it displayed the TRS, and that the speed bug could move by itself, and that it was recommended or mandatory to synchronise the TRS with the speed bug.
If yes, it's a bit stupid.
On the A220, possibly you would have to trim all the way, but also increase the speed bug in steps. That would be multiplying the number of actions to do.
If the A320 does aileron rolls after the gear is selected up, It's a bit stupid.
Joined: Feb 2003
Posts: 541
Likes: 336
From: Blue sky
All this just to make a point on your B777 A/T...? All this just to hear once you are right?
Last edited by BraceBrace; 25th July 2024 at 11:04.
Joined: Nov 1999
Aviation Qualifications: ATPL
Posts: 3,144
Likes: 741
From: UK
The OP seems to be terribly confused.
If the auto-thrust is "commanding too much thrust", it is because you have somehow told it to, or conversely, you have not told it to slow down. The Airbus FBW auto-thrust works really well and is very well integrated with the aircraft and the FBW. If you want to reduce thrust to slow down, you need to press for managed speed, (having activated the Approach phase), or reduce the speed bug, or select the next stage of flap, for example.
(And do remember that Ground-speed Mini will call for increased thrust when a headwind gust occurs, which is the opposite way around to conventional aircraft, e.g. Boeings)..
Drop the gear early if things are getting a bit rushed and a bit fast. If you are still too fast, you also have speed brakes, but these really should not be needed unless you have badly mishandled the approach and the config changes.
Just work at it and observe and practice. Don't dismiss or criticise until you fully understand it.
If the auto-thrust is "commanding too much thrust", it is because you have somehow told it to, or conversely, you have not told it to slow down. The Airbus FBW auto-thrust works really well and is very well integrated with the aircraft and the FBW. If you want to reduce thrust to slow down, you need to press for managed speed, (having activated the Approach phase), or reduce the speed bug, or select the next stage of flap, for example.
(And do remember that Ground-speed Mini will call for increased thrust when a headwind gust occurs, which is the opposite way around to conventional aircraft, e.g. Boeings)..
Drop the gear early if things are getting a bit rushed and a bit fast. If you are still too fast, you also have speed brakes, but these really should not be needed unless you have badly mishandled the approach and the config changes.
Just work at it and observe and practice. Don't dismiss or criticise until you fully understand it.
Thread Starter
Joined: Apr 2022
Posts: 267
Likes: 21
From: France
I've flown my first AT OFF approach on the 777.
The triple seven is not a beginner plane, I flew hundreds of them on A320 before that
Around 90% with AT OFF and 60% of them with FD OFF as well.
This makes me think that I haven't started talking about the FDs on this plane, but it's not the topic.
If the auto-thrust is "commanding too much thrust", it is because you have somehow told it to, or conversely, you have not told it to slow down. The Airbus FBW auto-thrust works really well and is very well integrated with the aircraft and the FBW. If you want to reduce thrust to slow down, you need to press for managed speed, (having activated the Approach phase), or reduce the speed bug, or select the next stage of flap, for example.
If I have a speed bug 20kt below my current speed, I want idle.
Indeed, the Airbus system worked pretty well, even though it was still anticipating a bit too much, but the 777 A/T anticipates way too much.
The system can't know that you're going to order the next step of flaps and reduce the speed bug, the pilot does. So the pilot can decide to reduce to idle, while the system would take a margin and command some thrust.
Also during flare the 777 system sometimes retarded too late, leading to some floating. The 777 A/T is overridable and I found that to be fortunate since we have to overide it quite often. During the sim training I flew with a guy coming from the 37. He didn't hesitate to constantly override it.
Joined: Jul 2023
Posts: 61
Likes: 15
From: United States
I do agree with the use of A/T, on approach and close final. G550 / KTEB / RW19 / VFR. Winds, not that bad. What happened. One of the last thing the A/T did to me, on short final, was to over compensate for a decreasing airspeed from target. Throttles pushed up to compensate for a very small difference which caused a longer touchdown point. After that I decided I can do that better.