Thrust levers - moving or not?
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RAT 5
Keeping a hand on thrust lever is a habit for moving throttles. In AB FBW it doesn't make sense since it gives you no clue as to what's happening. you watch the actual thrust. This can make pilots believe that it is never required. So they need to be told that at least during an approach you need to keep your hand on the thrust lever not because it gives any clue on approach but to switch to manual thrust if required without grabbing something else in a hurry. Approach starts a long way up so SOP defines a limit. The habit of disregarding SOPs is not necessarily a sign of superior piloting skill. Many do it out of ignorance also. In FBW, armed with only FCOM/FCTM you are not in a position to change or device your own procedures. Some airlines have almost come to grief doing that. You need to keep the manufacturer in the loop because behind the SOP software/hardware and design characteristics are involved. In FBW it may not be what it appears.
Keeping a hand on thrust lever is a habit for moving throttles. In AB FBW it doesn't make sense since it gives you no clue as to what's happening. you watch the actual thrust. This can make pilots believe that it is never required. So they need to be told that at least during an approach you need to keep your hand on the thrust lever not because it gives any clue on approach but to switch to manual thrust if required without grabbing something else in a hurry. Approach starts a long way up so SOP defines a limit. The habit of disregarding SOPs is not necessarily a sign of superior piloting skill. Many do it out of ignorance also. In FBW, armed with only FCOM/FCTM you are not in a position to change or device your own procedures. Some airlines have almost come to grief doing that. You need to keep the manufacturer in the loop because behind the SOP software/hardware and design characteristics are involved. In FBW it may not be what it appears.
Thread Starter
Centaurus, your Chinese SIM story is very scary. I suspect that the Chief pilot was not up to the job, and that he probably was one of those delightful barons who did not like a woman (the interpretor) or you pointing out his mistakes.
Given the Chief pilot's appalling lack of ability I would have let the SIM crash. No point saving a person's embarrassment if they are clearly not up to the job and peoples' lives might be at stake.
A colleague who now flies with another asian airline sat on the jumpseat on a line flight and during the climb watched both pilots reading newspapers that obscured the instruments, and he later had to speak up when they had both mis-set the arrival QNH by 8mb.
Back to the thrust levers. Flying Airbus, we keep our hand on the non-moving levers on approach and the other hand on the side stick. At any moment something could happen or a failure or a runaway might occur which would require instant manual reversion, or a Go-Around, so the hands should be on the controls.
As far a nudging or helping the A/THR, I suppose that on Airbus we learn to trust the A/THR and how it will react, (or not react) coupled with good instrument scanning. In theory, we could use the levers in a similar way to Boeings: nudge the levers just forward of the CLB gate and back to speed up, and backward from the CLB gate to limit the maximum thrust available to the A/THR to slow down.
However we should not invent our own procedures, because there may be unintended consequences.
Given the Chief pilot's appalling lack of ability I would have let the SIM crash. No point saving a person's embarrassment if they are clearly not up to the job and peoples' lives might be at stake.
A colleague who now flies with another asian airline sat on the jumpseat on a line flight and during the climb watched both pilots reading newspapers that obscured the instruments, and he later had to speak up when they had both mis-set the arrival QNH by 8mb.
Back to the thrust levers. Flying Airbus, we keep our hand on the non-moving levers on approach and the other hand on the side stick. At any moment something could happen or a failure or a runaway might occur which would require instant manual reversion, or a Go-Around, so the hands should be on the controls.
As far a nudging or helping the A/THR, I suppose that on Airbus we learn to trust the A/THR and how it will react, (or not react) coupled with good instrument scanning. In theory, we could use the levers in a similar way to Boeings: nudge the levers just forward of the CLB gate and back to speed up, and backward from the CLB gate to limit the maximum thrust available to the A/THR to slow down.
However we should not invent our own procedures, because there may be unintended consequences.
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Thank you, guys, for the information. I ask this from a human factors point of view.
We use many senses when flying, subtle and often without realising it. Sound is one that not many are aware of. It was ably demonstrated when on B733, on approach, you had the wipers beating back & forth like having a bag of bolts in the washing m/c. It deadened all outside noises including the engines. Turning them off was such a relief.
Another subtle sense is touch. On approach, you see the speed dribbling back (or increasing) and you 'feel' the T/L's opposing the drift, or you do it yourself with a suitable nudge. It's instinctive. You see, you feel, you hear.
Now in non-moving T/L's you remove the 'feel' and rely purely on sight = scan, then sound. I see every day, and in the sim, B738, the younger pilots and cadets with tunnel vision on the PFD. They don't even look at the ND never mind the N1% gauges. IMHO they are as important as a flight control imparting energy to the a/c. Give it the wrong amount and it ain't going to do the job. You can anticipate the speed will decay or increase. I try to encourage PM to include them in their scan to ensure PF is on the ball.
So my question; with non-moving T/L's you have to be more vigilant with the N1% and the scan is a very visual only affair. Do you find this instinctive and are you aware of any more work load? Or do you notice many pilots having blind faith in the system and not monitoring it at all?
Notice I'm not advocating one system being better than the other; I'm asking from those who've operated both if they are aware of any change in workload between the two. Or any other comments they'd like to share.
We use many senses when flying, subtle and often without realising it. Sound is one that not many are aware of. It was ably demonstrated when on B733, on approach, you had the wipers beating back & forth like having a bag of bolts in the washing m/c. It deadened all outside noises including the engines. Turning them off was such a relief.
Another subtle sense is touch. On approach, you see the speed dribbling back (or increasing) and you 'feel' the T/L's opposing the drift, or you do it yourself with a suitable nudge. It's instinctive. You see, you feel, you hear.
Now in non-moving T/L's you remove the 'feel' and rely purely on sight = scan, then sound. I see every day, and in the sim, B738, the younger pilots and cadets with tunnel vision on the PFD. They don't even look at the ND never mind the N1% gauges. IMHO they are as important as a flight control imparting energy to the a/c. Give it the wrong amount and it ain't going to do the job. You can anticipate the speed will decay or increase. I try to encourage PM to include them in their scan to ensure PF is on the ball.
So my question; with non-moving T/L's you have to be more vigilant with the N1% and the scan is a very visual only affair. Do you find this instinctive and are you aware of any more work load? Or do you notice many pilots having blind faith in the system and not monitoring it at all?
Notice I'm not advocating one system being better than the other; I'm asking from those who've operated both if they are aware of any change in workload between the two. Or any other comments they'd like to share.
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RAT 5
Let me analyse what you say:
1. On approach, you see the speed dribbling back (or increasing) and you 'feel' the T/L's opposing the drift, or you do it yourself with a suitable nudge. It's instinctive. You see, you feel, you hear. First it is not instinctive but habitual and habits can be unlearned or learned. Second suitable nudge is not manufacturer's recommendation. Also it doesn't ensure that N1 is increasing. In Airbus also you can nudge forward against manufacturer's recommendation and off course you see and hear.
2. They don't even look at the ND never mind the N1% gauges IMHO they are as important as a flight control imparting energy to the a/c. Give it the wrong amount and it ain't going to do the job. You can anticipate the speed will decay or increase.
N1 is a reference. The basic parameter that attracts you to N1 is speed. The anticipation of decay or increase of speed doesn't take much as speed trend arrow does it for you. The problem is not looking at N1 gauge but not looking at the speed at all till the point of crash experienced and inexperienced alike.
3. So my question; with non-moving T/L's you have to be more vigilant with the N1% and the scan is a very visual only affair. Do you find this instinctive and are you aware of any more work load?
As long as one knows how to manage trend arrow you don't need any more vigilance. Maintain correct pitch and manage trend there is absolutely no problem.
Let me analyse what you say:
1. On approach, you see the speed dribbling back (or increasing) and you 'feel' the T/L's opposing the drift, or you do it yourself with a suitable nudge. It's instinctive. You see, you feel, you hear. First it is not instinctive but habitual and habits can be unlearned or learned. Second suitable nudge is not manufacturer's recommendation. Also it doesn't ensure that N1 is increasing. In Airbus also you can nudge forward against manufacturer's recommendation and off course you see and hear.
2. They don't even look at the ND never mind the N1% gauges IMHO they are as important as a flight control imparting energy to the a/c. Give it the wrong amount and it ain't going to do the job. You can anticipate the speed will decay or increase.
N1 is a reference. The basic parameter that attracts you to N1 is speed. The anticipation of decay or increase of speed doesn't take much as speed trend arrow does it for you. The problem is not looking at N1 gauge but not looking at the speed at all till the point of crash experienced and inexperienced alike.
3. So my question; with non-moving T/L's you have to be more vigilant with the N1% and the scan is a very visual only affair. Do you find this instinctive and are you aware of any more work load?
As long as one knows how to manage trend arrow you don't need any more vigilance. Maintain correct pitch and manage trend there is absolutely no problem.
Last edited by vilas; 17th Aug 2015 at 14:42.
Thread Starter
Hi RAT.
For what it's worth, (and I have never flown moving A/THR levers), I find the Airbus easy to fly and interpret. If the speed bleeds away, I see it on the speed tape and trend arrow. I feel the reduction of energy by the change in pitch and sink, and see the pitch trim wheel moving. While this is happening I flick my eyes to the N1 or EPR gauges and expect to see the blue arc(s) appear that signifies a change of thrust command. Then I expect to see the N1 increase in response to the demand and I sense the speed increase through all the cues I just mentioned, including sound, as you say. I don't think that is any more work load than an aircraft with moving levers, and non moving levers do force me to keep up a good instrument scan which is a good thing.
So although the thrust levers are static, I am still able to assimilate the speed state of the aircraft. However, if the A/THR is being lazy or misbehaving, then it is harder to tweak than moving levers.
The danger is that by feeling the levers moving, some pilots assume that the A/THR is working. It usually is, but the levers are only the input, i.e. the demand to the engines, whereas pilots should be checking the output, i.e. the result of the demand, which in the case of the engines is the N1/EPR gauges. It appears anecdotally and from several speed related crashes that if the levers stop moving owing to a fault, or incorrect mode selection then this does not always get noticed by pilots, so a proper instrument scan is very important, as it always has been.
As we all should know and Centaurus's SIM demonstrated, not making a proper instrument scan can lead to disaster.
For what it's worth, (and I have never flown moving A/THR levers), I find the Airbus easy to fly and interpret. If the speed bleeds away, I see it on the speed tape and trend arrow. I feel the reduction of energy by the change in pitch and sink, and see the pitch trim wheel moving. While this is happening I flick my eyes to the N1 or EPR gauges and expect to see the blue arc(s) appear that signifies a change of thrust command. Then I expect to see the N1 increase in response to the demand and I sense the speed increase through all the cues I just mentioned, including sound, as you say. I don't think that is any more work load than an aircraft with moving levers, and non moving levers do force me to keep up a good instrument scan which is a good thing.
So although the thrust levers are static, I am still able to assimilate the speed state of the aircraft. However, if the A/THR is being lazy or misbehaving, then it is harder to tweak than moving levers.
The danger is that by feeling the levers moving, some pilots assume that the A/THR is working. It usually is, but the levers are only the input, i.e. the demand to the engines, whereas pilots should be checking the output, i.e. the result of the demand, which in the case of the engines is the N1/EPR gauges. It appears anecdotally and from several speed related crashes that if the levers stop moving owing to a fault, or incorrect mode selection then this does not always get noticed by pilots, so a proper instrument scan is very important, as it always has been.
As we all should know and Centaurus's SIM demonstrated, not making a proper instrument scan can lead to disaster.
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Only Guessing, But...
I admit that this is no more than a WAG! My WAG is that those who hand-fly frequently probably appreciate the visual ques and physical movement of the levers. Those who do not hand-fly frequently are probably relying on graphic displays to report thrust details, rather than lever position. While firm SOPs 'may' help, every pilot has his or her own routine for scanning and obtaining important information during 'critical phases' of flight. As long as s/he obtains the information from a reliable source, does it matter which source is used?
I'm old, grey and very used to pushing/pulling multiple levers, must of which have friction adjustments. If I noticed an un-commanded change of any lever's position, I think I'd test it a little bit, reset it as necessary and tighten the friction lock.
(FBW, including auto-thrust) is not for me. It is perfectly OK for our grand-kids, but only if they fully understand exactly how every component works and interacts with every other. Some do - and some do not.) And please forgive the rant.
I'm old, grey and very used to pushing/pulling multiple levers, must of which have friction adjustments. If I noticed an un-commanded change of any lever's position, I think I'd test it a little bit, reset it as necessary and tighten the friction lock.
(FBW, including auto-thrust) is not for me. It is perfectly OK for our grand-kids, but only if they fully understand exactly how every component works and interacts with every other. Some do - and some do not.) And please forgive the rant.
