FBW question
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FBW question
To quote....
"There is to be even greater innovation in the cockpit of the fly-by-wire G500 and G600, which will be the first Gulfstreams to feature active sidestick controls. According to Mark Kohler, Gulfstream vice president for advanced aircraft programs, the airframer was unwilling to make the shift to a sidestick control until BAE Systems adapted technology originally developed for fighters for civil use. “The system’s active force feedback provides a classic airplane feel, and it simulates the feel of mechanically linked sticks,'”
Does Airbus have this active force feedback that Gulfstream says they were waiting for?
"There is to be even greater innovation in the cockpit of the fly-by-wire G500 and G600, which will be the first Gulfstreams to feature active sidestick controls. According to Mark Kohler, Gulfstream vice president for advanced aircraft programs, the airframer was unwilling to make the shift to a sidestick control until BAE Systems adapted technology originally developed for fighters for civil use. “The system’s active force feedback provides a classic airplane feel, and it simulates the feel of mechanically linked sticks,'”
Does Airbus have this active force feedback that Gulfstream says they were waiting for?
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Here's another few then...
Airbuses and stalling.
As I understand it, in normal operation FBW Airbus aircraft are designed to prevent a stall from occurring. But what if it does? So firstly, how does an FBW Airbus (A320 type) announce that it is stalled? Secondly, how does it recover from a stall? Does it do this by itself ie. recognise that it is stalled and reduce the AoA, change the position of the elevator trim if inappropriate, apply thrust etc. or does it throw up its hands, change the active flight law (upgrade/downgrade) and let the pilots deal with the problem? Lastly, how often is this manoeuvre practiced?
As I understand it, in normal operation FBW Airbus aircraft are designed to prevent a stall from occurring. But what if it does? So firstly, how does an FBW Airbus (A320 type) announce that it is stalled? Secondly, how does it recover from a stall? Does it do this by itself ie. recognise that it is stalled and reduce the AoA, change the position of the elevator trim if inappropriate, apply thrust etc. or does it throw up its hands, change the active flight law (upgrade/downgrade) and let the pilots deal with the problem? Lastly, how often is this manoeuvre practiced?
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Read up on Alpha Prot, Max and Floor.
There is, IMHO, rather a big deal being made on here about the difference between recovery from the approach to a Stall, and from an "actual" stall.
I cannot recall many types where the drills / actions required differ. Including the Airbus A320 series. Yes - the degree / magnitude of response required may differ but the "drill" remains the same.
When you apply FBW to it the software / automation will often degrade, if only since by definition, it either has a fault, or external circumstances out of it's control, if a stall occurs. The "degrade" basics are not just "throwing it's hands in the air", but ensuring inappropriate control inputs are not made due to the fault etc.
Read up on Alpha Prot, Max and Floor.
There is, IMHO, rather a big deal being made on here about the difference between recovery from the approach to a Stall, and from an "actual" stall.
I cannot recall many types where the drills / actions required differ. Including the Airbus A320 series. Yes - the degree / magnitude of response required may differ but the "drill" remains the same.
When you apply FBW to it the software / automation will often degrade, if only since by definition, it either has a fault, or external circumstances out of it's control, if a stall occurs. The "degrade" basics are not just "throwing it's hands in the air", but ensuring inappropriate control inputs are not made due to the fault etc.
Airbus does not currently use active force feedback; the technology was unavailable at the time of design. Airbus side-sticks have some force-feel about the null position.
Force (positon) feedback can provide an indication of the aircraft trim condition about a datum speed; this assumes that autotrim follow-up is not used.
Mechanical or similar hyd/elect technology enables cross coupled feel/positon from the other stick. However with any system the problem of a system jam/restriction has to be solved – in the stick, in the cross coupling, and elsewhere in the system. Airbus uses an elegant electronic solution, but this comes with novel aspects which require understanding – control priority/lockout. Fighter aircraft generally don't have a problem with cross coulping.
Some of the arguments for non-feedback systems assume a high degree of automatic flight, and particularly automation for speed control – where stick force is an indicator for trim speed. There was a further argument about speed displays, where if a speed tape was inferior to dials there would be greater dependency on automated speed control.
There may be some concern if sidesticks are used in smaller aircraft without A/T and/or weak speed displays; however Gulfstream’s philosophy appears to be aligned with the heavy jets, and notably their first tape speed scales were opposite to others in the industry.
Stall avoidance in FBW aircraft is part of the overall control system, but not directly associated with the stick design. Conventional systems provide some stall awareness / protection from stick position.
Force (positon) feedback can provide an indication of the aircraft trim condition about a datum speed; this assumes that autotrim follow-up is not used.
Mechanical or similar hyd/elect technology enables cross coupled feel/positon from the other stick. However with any system the problem of a system jam/restriction has to be solved – in the stick, in the cross coupling, and elsewhere in the system. Airbus uses an elegant electronic solution, but this comes with novel aspects which require understanding – control priority/lockout. Fighter aircraft generally don't have a problem with cross coulping.
Some of the arguments for non-feedback systems assume a high degree of automatic flight, and particularly automation for speed control – where stick force is an indicator for trim speed. There was a further argument about speed displays, where if a speed tape was inferior to dials there would be greater dependency on automated speed control.
There may be some concern if sidesticks are used in smaller aircraft without A/T and/or weak speed displays; however Gulfstream’s philosophy appears to be aligned with the heavy jets, and notably their first tape speed scales were opposite to others in the industry.
Stall avoidance in FBW aircraft is part of the overall control system, but not directly associated with the stick design. Conventional systems provide some stall awareness / protection from stick position.
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I've often thought that some force feedback is the answer to Airbus' problem.
If the stick position is motored to show the summed flight surface movements, it would be easy to provide the means to show the uncoupling in jammed control conditions by making the individual sticks show the movement in that side only. Who needs a load of ECAM messages when one moves and the other doesn't!
Also, if a pressure sensor is used on the stick neck, as in some fighters, you push the stick to move it, but the force is sensed and fed to the FBW system. The actual movement is a feedback to you. Thus any interference of Alpha Floor, or similar can be felt directly as the stick not responding in a natural way. Also if they moved the bloody throttles as well, you'd actually be able to FEEL the plane flying for you and be in the loop if you disconnect on a windy day or whatever.
I suspect it's this lack of feedback to provide feel is why many like me really don't want to fly Airbus products anytime soon.....
If the stick position is motored to show the summed flight surface movements, it would be easy to provide the means to show the uncoupling in jammed control conditions by making the individual sticks show the movement in that side only. Who needs a load of ECAM messages when one moves and the other doesn't!
Also, if a pressure sensor is used on the stick neck, as in some fighters, you push the stick to move it, but the force is sensed and fed to the FBW system. The actual movement is a feedback to you. Thus any interference of Alpha Floor, or similar can be felt directly as the stick not responding in a natural way. Also if they moved the bloody throttles as well, you'd actually be able to FEEL the plane flying for you and be in the loop if you disconnect on a windy day or whatever.
I suspect it's this lack of feedback to provide feel is why many like me really don't want to fly Airbus products anytime soon.....
TD, Airbus does not have a problem, but some sections of the industry may have.
There are many myths and folk laws about FBW, often from basic training – ‘it can’t stall, thus no need to train that aspect”.
FBW is a particular technology primarily associated with the transmission of piloting input to control activation. The technology replaces or adds to the many restricting and aiding devices in conventional controls.
The industry problem is with the understanding of these aspects of the technology, its intended use, and limitations.
The latest technology enabling a force feedback side stick offers opportunity for improvement, but it is not an essential aspect to cure ill formed biases.
Many aspects of manoeuvring flight don’t require force feedback or even sick movement, but for aiding awareness of flight, protections, etc, then the stick provides a means of feedback. But if you haven’t got your hands on the stick, then how is this awareness to be provided, and if provided, seen and used?
Thats a real problem, but it doesn’t involve FBW directly.
There are many myths and folk laws about FBW, often from basic training – ‘it can’t stall, thus no need to train that aspect”.
FBW is a particular technology primarily associated with the transmission of piloting input to control activation. The technology replaces or adds to the many restricting and aiding devices in conventional controls.
The industry problem is with the understanding of these aspects of the technology, its intended use, and limitations.
The latest technology enabling a force feedback side stick offers opportunity for improvement, but it is not an essential aspect to cure ill formed biases.
Many aspects of manoeuvring flight don’t require force feedback or even sick movement, but for aiding awareness of flight, protections, etc, then the stick provides a means of feedback. But if you haven’t got your hands on the stick, then how is this awareness to be provided, and if provided, seen and used?
Thats a real problem, but it doesn’t involve FBW directly.
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Airbus does not currently use active force feedback; the technology was unavailable at the time of design.
I guess the main issue why many pilots would like some force feedback is a position feedback of the other stick, not necessarily of flight control positions.
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...which is what I was aiming at. Not force feedback but position feedback. I do feel the force feedback comes from the need to show the position of the flight surfaces. Thus if it moves less at higher speed, or the trim is out, etc, you would feel more resistance to your hand.
It's putting the pilot back in the loop, something Airbus neglected from the start. We start as small aircraft students and if you move to a large airliner too soon, you never develop the skills and feel.....I came up the traditional way, and so many companies look down their noses at people from this route. When it comes down to it, the absolute basic reversion is pitch power and feel. If you never had it, you never will. Sully has it in spades and many others too. Just my opinion, of course. I'm just arguing that AB doesn't value Pilot skills enough despite many crashes that may have been prevented if they had. It's the philosophy of flying. The hardware can make a difference!
Edited to say I do appreciate there are many very skilled and capable pilots out there flying Airbus products! I also know there are many operators who value these skills and tailor courses to keep them.
I just don't like the lifeless nature of the stick and throttles- it's very off putting! It's purely this that tells me what Airbus think of pilots!
It's putting the pilot back in the loop, something Airbus neglected from the start. We start as small aircraft students and if you move to a large airliner too soon, you never develop the skills and feel.....I came up the traditional way, and so many companies look down their noses at people from this route. When it comes down to it, the absolute basic reversion is pitch power and feel. If you never had it, you never will. Sully has it in spades and many others too. Just my opinion, of course. I'm just arguing that AB doesn't value Pilot skills enough despite many crashes that may have been prevented if they had. It's the philosophy of flying. The hardware can make a difference!
Edited to say I do appreciate there are many very skilled and capable pilots out there flying Airbus products! I also know there are many operators who value these skills and tailor courses to keep them.
I just don't like the lifeless nature of the stick and throttles- it's very off putting! It's purely this that tells me what Airbus think of pilots!
Last edited by RVF750; 18th Jan 2015 at 11:56.
Validation of pilot skills lies strictly with the operator and local licencing authority. It is no Airbus' fault if some of them go with whatever they can get away with nor it should take any credit for my 320 type rating training starting with five sessions of flying in Direct law, no flight director, autopilot nor autothrust. Also it is no coincidence that a classmate of mine that started in A320 RHS at the tender TT of 200, had aposlutey no problems 9 years and 6000 hours later with conversion to the left seat of Q400.
Stories about Airbus not requiring skilled pilot or Boeing being natural pilot's aeroplane are just black marketing rumours, usually perpetuated by the good folks clueless about either product.
Having flown 320 and being current in 737NG, I know which one I prefer.
The one that pays better.
Stories about Airbus not requiring skilled pilot or Boeing being natural pilot's aeroplane are just black marketing rumours, usually perpetuated by the good folks clueless about either product.
Having flown 320 and being current in 737NG, I know which one I prefer.
The one that pays better.
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Not only incorrect, but blatant prejudice. By making the sidesticks passive, all Airbus was doing was acknowledging the fact that since the advent of hydraulically-powered controls, the "tactile" feedback through the column was a simulation only, and a simulation which risked misleading pilots if the systems driving the feedback suffered a malfunction.
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I think the force feedback idea needs revisiting by Airbus...
Take the training environment, this is from here, under simulator assessment
For me, that summarises what has been said for years on the line about monitoring Airbus approaches...
Take the training environment, this is from here, under simulator assessment
In the first of these ‘unusual’ approaches, a manual approach was flown with autothrust, but the ‘trainee’ ceased to make sidestick inputs at 50 ft RA. The TRE(A) was unable to intervene in time and the aircraft struck the runway without a flare. In other ‘unusual’ approaches, the TRE(A) was again unable to intervene, or intervened too late, to prevent a hard landing.
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There is a relatively minor problem with sidestick feel. The aileron detent (if I can call it that) operates in the exact same position regardless of the fore and aft movement of the sidestick. Since the stick fore and aft movement is to the side of each pilot, pitch control is not a straight pressure towards the pilot. In ordinary flying conditions this is easy to get used to.
During a missed approach, especially from a low height, there is a pitch feel requiring additional rearward force on the sidestick. This increased force has a desensing effect for the feel of the aileron "detent", often resulting in a small unintended right turn for captain as PF, or a small left turn for FO an PF. This small turn and a correction to desired heading is evident on simulator tracking history.
The point is, that when larger than normal back pressure is required, the lateral feel should also be increased.
During a missed approach, especially from a low height, there is a pitch feel requiring additional rearward force on the sidestick. This increased force has a desensing effect for the feel of the aileron "detent", often resulting in a small unintended right turn for captain as PF, or a small left turn for FO an PF. This small turn and a correction to desired heading is evident on simulator tracking history.
The point is, that when larger than normal back pressure is required, the lateral feel should also be increased.
I have flown C172, PA28, Zlin, PA34, SD360, Q400, A320/321 and A330.
Given that my day job is commercial passenger flying - involving many aspects of flight in busy airspace, or at the tail end of an 8 hour transatlantic crossing, I am happy to let the FBW do some of the donkey work; trimming and prevent overstresses etc. while we monitor and 'conduct' the flight. One soon develops a "feel" for what is going on without having to have an actual 'feel' through the side stick. I can see what is going on by scanning my instruments. If I want to actually FLY an aircraft, and trim it etc., I could always go back to the Zlin !
Like any system, FBW is not perfect and has its gotcha's. e.g. AF447 et al. I personally think we should have more training rather than the minimum required. I think we should be actively encouraged to hand fly more often - like recording LVP approaches, and I think the side sticks should physically follow each other so we both can see or feel what the other pilot is doing. Obviously there would then need to be a disconnect system, but the one in the Q400 seemed to work very well, (albeit they use mechanical yokes not side sticks).
Just my 2p worth.
Given that my day job is commercial passenger flying - involving many aspects of flight in busy airspace, or at the tail end of an 8 hour transatlantic crossing, I am happy to let the FBW do some of the donkey work; trimming and prevent overstresses etc. while we monitor and 'conduct' the flight. One soon develops a "feel" for what is going on without having to have an actual 'feel' through the side stick. I can see what is going on by scanning my instruments. If I want to actually FLY an aircraft, and trim it etc., I could always go back to the Zlin !
Like any system, FBW is not perfect and has its gotcha's. e.g. AF447 et al. I personally think we should have more training rather than the minimum required. I think we should be actively encouraged to hand fly more often - like recording LVP approaches, and I think the side sticks should physically follow each other so we both can see or feel what the other pilot is doing. Obviously there would then need to be a disconnect system, but the one in the Q400 seemed to work very well, (albeit they use mechanical yokes not side sticks).
Just my 2p worth.
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Hi John,
Have the authors of this paper got it completely wrong then?
Pilots in the loop? Airbus and the FBW side stick « Critical Uncertainties
"A key cognitive engineering flaw
The decision to use passive controllers unfortunately introduced a cognitive engineering design error in the form of the absence of tactile feedback to the pilots. This in turn transferred the behavioural cue from the tactile (hands on stick) to the visual channel of the pilots, with the design implementation further translating the cue from an analog kinaesthetic to visual symbolic form, which in turn requires higher levels of cognitive processing. This visual cue then competes for attentional resources in the visual channel and requires additional ‘mental bandwidth’ (e.g. symbology requires abstract processing) to handle. The net result an ineffective coordination mechanism under high stress conditions."
There is no feed back through the Thrust Levers in auto thrust or TOGA LOCK. More competition for 'mental bandwidth'.
Anyone who feels 'out of the loop' flying an Airbus FBW product needs to take a look at themselves rather than the aeroplane design.
Pilots in the loop? Airbus and the FBW side stick « Critical Uncertainties
"A key cognitive engineering flaw
The decision to use passive controllers unfortunately introduced a cognitive engineering design error in the form of the absence of tactile feedback to the pilots. This in turn transferred the behavioural cue from the tactile (hands on stick) to the visual channel of the pilots, with the design implementation further translating the cue from an analog kinaesthetic to visual symbolic form, which in turn requires higher levels of cognitive processing. This visual cue then competes for attentional resources in the visual channel and requires additional ‘mental bandwidth’ (e.g. symbology requires abstract processing) to handle. The net result an ineffective coordination mechanism under high stress conditions."
There is no feed back through the Thrust Levers in auto thrust or TOGA LOCK. More competition for 'mental bandwidth'.
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john_smith bluntly put it and Goldenrivett has retorted with some evidence. I think the truth is in between. What JS is saying is that the airbus FBW is not a big deal and I agree with him. An average pilot can easily adjust to its design. The adverse opinions about AB FBW are because it is a departure from other airplanes pilots fly. You develop certain habits, feels and clues and once on Airbus you need to relocate a few things differently. There are pilots out there who switched to Airbus straight out of flying schools and they have been flying it without fuss. They may find it difficult to adapt to conventional airplanes and not vice versa. It is a very easy airplane to fly does not demand high levels of stick rudder skills. Majority of flights get conducted routinely and even many careers end without having faced any serious abnormality and Airbus is a very good airplane for that. It has had few quirks in its protections mainly the high angle of attack protections but Airbus FBW is too good a concept to discard totally. It has its followers and popularity and there can be no doubt that Airbus is here to stay.
j s, it’s a little harsh to state that the authors are ‘wrong’; they have an opinion which should be respected.
However, I agree that the article is of little value because it appears to be biased by hindsight and tailored towards a particular agenda.
A meaningful discussion requires an understanding of the design principles and objectives of many years ago, the assumptions made about piloting skills, education, training, and procedures. These should be compared with today’s standards and expectations.
Many of the ‘problems’ stated in recent times stem for this gap in understanding; - different points of view, different operational environment, training standards, social expectations, etc.
j s, vilas,
However, I agree that the article is of little value because it appears to be biased by hindsight and tailored towards a particular agenda.
A meaningful discussion requires an understanding of the design principles and objectives of many years ago, the assumptions made about piloting skills, education, training, and procedures. These should be compared with today’s standards and expectations.
Many of the ‘problems’ stated in recent times stem for this gap in understanding; - different points of view, different operational environment, training standards, social expectations, etc.
j s, vilas,
