View Poll Results: Should the Speed Tape be inverted
YES
1
50.00%
NO
1
50.00%
Voters: 2. This poll is closed
A320 Speed tape on PFD
Guest
Posts: n/a
A320 Speed tape on PFD
Ever since i read the report on the Gulf Air A320 Accident in Bahrain, the bit about the '11 seconds of forward input on the sidestick from the time overspeed warning sounded,right upto the impact ' has been nagging me.
The primary finding,simply put, is ' pilot disorientation'
However, it is my suspicion that the Speed Tape on the PFD(primary flight display) could have contributed significantly to the setting in, of this disorientation
The Speed Tape on the A320s PFDs, as also those i suppose in other 'Glass Cockpits'including Boeings,runs from bottom to top.
That means that the low speed end is at the bottom and the high speed end at the top.Because of this layout,all warnings associated with "OVERSPEEDS" including VFE appear RED on the TOP OF the speed Tape.
Just think,given they lack of visual referances,the crews low experience on type,and their higher stress levels-- it is not unconceivable that in order to avoid the flap overspeed red barber pole on top of the tape the PF instinctively pushed the stick forward and kept it there.
After all, in response to TCAS generated RAs on the Vertical Speed tape arn't we suppossed to directly use the sidestick to fly the GREEN and avoid the RED area.
It is my opinion that, if the Speed tape were inverted it would reflect more accurately the side stick response expected.
OVERSPEED barberpole comming up from the bottom would require STICK BACK response and LOWSPEED(VLS etc) warnings barberpole coming down from the top would require a STICK FORWARD response.
I wonder why no one has thought of this already, in this day and
age of ERGONOMICS.
If someone in the industry knows whether this idea has ever been considered,i would like to know.
Or is it that the, cost/benefit analysis to change the software on thousands of glasscockpit PFDs is stacked in favour of Status Quo.
The primary finding,simply put, is ' pilot disorientation'
However, it is my suspicion that the Speed Tape on the PFD(primary flight display) could have contributed significantly to the setting in, of this disorientation
The Speed Tape on the A320s PFDs, as also those i suppose in other 'Glass Cockpits'including Boeings,runs from bottom to top.
That means that the low speed end is at the bottom and the high speed end at the top.Because of this layout,all warnings associated with "OVERSPEEDS" including VFE appear RED on the TOP OF the speed Tape.
Just think,given they lack of visual referances,the crews low experience on type,and their higher stress levels-- it is not unconceivable that in order to avoid the flap overspeed red barber pole on top of the tape the PF instinctively pushed the stick forward and kept it there.
After all, in response to TCAS generated RAs on the Vertical Speed tape arn't we suppossed to directly use the sidestick to fly the GREEN and avoid the RED area.
It is my opinion that, if the Speed tape were inverted it would reflect more accurately the side stick response expected.
OVERSPEED barberpole comming up from the bottom would require STICK BACK response and LOWSPEED(VLS etc) warnings barberpole coming down from the top would require a STICK FORWARD response.
I wonder why no one has thought of this already, in this day and
age of ERGONOMICS.
If someone in the industry knows whether this idea has ever been considered,i would like to know.
Or is it that the, cost/benefit analysis to change the software on thousands of glasscockpit PFDs is stacked in favour of Status Quo.
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
nightbird, I have closed your poll on this subject, not because I think the subject is not interesting and useful, but because I think it is.
A poll does not provide any useful information, opposing viewpoints, explanations or anything else, and I would instead urge all contributors to write what they think.
In my experience, speedtapes effectively command power lever movement, not stick/column.
In the orientation of their instruments, Airbus are merely continuing the industry norm. To invert it would be to invite disaster from the point of view of non-Airbi drivers converting and having to get used to it.
Just my opinion - I am sure many others will have other opinions...
A poll does not provide any useful information, opposing viewpoints, explanations or anything else, and I would instead urge all contributors to write what they think.
In my experience, speedtapes effectively command power lever movement, not stick/column.
In the orientation of their instruments, Airbus are merely continuing the industry norm. To invert it would be to invite disaster from the point of view of non-Airbi drivers converting and having to get used to it.
Just my opinion - I am sure many others will have other opinions...
Guest
Posts: n/a
Captain Stable,your point regarding the poll taken.
i am still getting the hang of things at PPrune.
just "exploring the envelope" pushing all the buttons that i find!
i should settle down presently,thank you
Getting back to the point i am trying to make about Speed tapes.
You are absolutely correct that the Speed tape commands the Thrust generated(in the A320 auto thrust system,the power lever itself does not move,which is good for maintainability,but its actually one less cue available to the pilots--but thats another story!)
However, had both the auto thrust AND the auto pilot been kept engaged during the "Go-Around", this unfortunate accident would not have occured in the first place.
On the A320 VISUAL approaches are flown with the FDs(Flight Directors) and APs(Auto Pilots) OFF.
During NON-PRECISION approachs,if the NAV(Navigation)accuracy is LOW,the Aeroplane is supposed to be flown on "Selected Guidance"(i.e. by direct inputs from Pilot Flying) and not "Managed Guidance" (by the FMGSi.e. the Flight Management and Guidance System).Because flying"Selected" involves using the "Heading" as well as the "Vertical Speed" knobs on the FCU(flight control unit)which commands the FDs and APs,and since this can sometimes be a frustrating exercise,compared to flying "hands on" a lot of pilots prefer to disengage the FDs and APs, at this stage of the Approach,however the Auto Thrust is normally kept engaged.
This works very well if you go and make a landing.
But in case of a "Go Around" things can(and in this case did)go out of hand pretty fast.
the point to understand here is that,for the Go Around-- the thrust levers are moved from the "Climb gate" to the "TOGA gate".
And as long as they remain in the "TOGA gate" it efectively ceases to be an auto thrust system.
Yes thats right, the Speed tape no longer commands the thrust(Which remains at TOGA until the lever is brought back to
the "Climb gate")
The Autopilot is suppoesd to be re-engaged at acceleration alt(normally 1500 agl,but nothing prevents you from doing so earlier)
So what you have is, that one moment you are flying at a very high level of automation,come the time for a Go Around, and next you have 50000 lbs of thrust up your behind, and not too much time to get your act togather( usually, if you have rotated to the correct GA attitude, shooting past your Missed Approach altitude serves as a good reminder to get the Thrust levers back!).
I sure could use all the cues available to me,when i have to "Stick and Rudder" a Go-Around on a dark night after a not so stabilized Approach.
i must emphasize here, that this normally happens only in the case of GO-AROUND following a NON-PRECISION or VISUAL approach(which was the case in Bahrain)
ILS approaches and their missed approaches are flown with all the available automation ON,and hence you dont read about them
the next day.
I know all this fuss about lack of automation during a Go-Around, might sound a bit much to conventional types(i was,till a couple of years back,a Boeing 737-200 jockey myself)
But thats what the Man-Machine debate is all about
looking forward to hearing more on this.
nightbird
i am still getting the hang of things at PPrune.
just "exploring the envelope" pushing all the buttons that i find!
i should settle down presently,thank you
Getting back to the point i am trying to make about Speed tapes.
You are absolutely correct that the Speed tape commands the Thrust generated(in the A320 auto thrust system,the power lever itself does not move,which is good for maintainability,but its actually one less cue available to the pilots--but thats another story!)
However, had both the auto thrust AND the auto pilot been kept engaged during the "Go-Around", this unfortunate accident would not have occured in the first place.
On the A320 VISUAL approaches are flown with the FDs(Flight Directors) and APs(Auto Pilots) OFF.
During NON-PRECISION approachs,if the NAV(Navigation)accuracy is LOW,the Aeroplane is supposed to be flown on "Selected Guidance"(i.e. by direct inputs from Pilot Flying) and not "Managed Guidance" (by the FMGSi.e. the Flight Management and Guidance System).Because flying"Selected" involves using the "Heading" as well as the "Vertical Speed" knobs on the FCU(flight control unit)which commands the FDs and APs,and since this can sometimes be a frustrating exercise,compared to flying "hands on" a lot of pilots prefer to disengage the FDs and APs, at this stage of the Approach,however the Auto Thrust is normally kept engaged.
This works very well if you go and make a landing.
But in case of a "Go Around" things can(and in this case did)go out of hand pretty fast.
the point to understand here is that,for the Go Around-- the thrust levers are moved from the "Climb gate" to the "TOGA gate".
And as long as they remain in the "TOGA gate" it efectively ceases to be an auto thrust system.
Yes thats right, the Speed tape no longer commands the thrust(Which remains at TOGA until the lever is brought back to
the "Climb gate")
The Autopilot is suppoesd to be re-engaged at acceleration alt(normally 1500 agl,but nothing prevents you from doing so earlier)
So what you have is, that one moment you are flying at a very high level of automation,come the time for a Go Around, and next you have 50000 lbs of thrust up your behind, and not too much time to get your act togather( usually, if you have rotated to the correct GA attitude, shooting past your Missed Approach altitude serves as a good reminder to get the Thrust levers back!).
I sure could use all the cues available to me,when i have to "Stick and Rudder" a Go-Around on a dark night after a not so stabilized Approach.
i must emphasize here, that this normally happens only in the case of GO-AROUND following a NON-PRECISION or VISUAL approach(which was the case in Bahrain)
ILS approaches and their missed approaches are flown with all the available automation ON,and hence you dont read about them
the next day.
I know all this fuss about lack of automation during a Go-Around, might sound a bit much to conventional types(i was,till a couple of years back,a Boeing 737-200 jockey myself)
But thats what the Man-Machine debate is all about
looking forward to hearing more on this.
nightbird
Guest
Posts: n/a
Captain Stable,
Regarding the Gulf Air Flight , the Capt had elected to fly a visual Approach,after the Runway was changed from the ILS equipped 30, to a straight in for 12.
During this Approach they found themselves too "hot and high",hence the Go-around(following an unsuccessful 360 turn) with FDs and APs OFF and Auto Thurst in TOGA.
However, the point that i am trying to make remains that,in this kind of Stick and Rudder situation the Speed Diplay on the PFD would definately be more "user friendly" if it was inverted
Surely industry norms should be aimed at designing out the potential for misreading of Critical Displays.
Since the inverted tape "makes more sense" i think all drivers will get the hang of it easyly enough.
Wonder what the Ergonomics bods have to say about this
nightbird
Regarding the Gulf Air Flight , the Capt had elected to fly a visual Approach,after the Runway was changed from the ILS equipped 30, to a straight in for 12.
During this Approach they found themselves too "hot and high",hence the Go-around(following an unsuccessful 360 turn) with FDs and APs OFF and Auto Thurst in TOGA.
However, the point that i am trying to make remains that,in this kind of Stick and Rudder situation the Speed Diplay on the PFD would definately be more "user friendly" if it was inverted
Surely industry norms should be aimed at designing out the potential for misreading of Critical Displays.
Since the inverted tape "makes more sense" i think all drivers will get the hang of it easyly enough.
Wonder what the Ergonomics bods have to say about this
nightbird
Join Date: Jun 2000
Location: netherlands, amsterdam
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
About ergonomics:
About a year ago I made my way into the glass cockpit. Beforehand I was flying in the military flying with high performance classical instrumented airplanes and helicopters.
In the beginning it took me quite some time to interpreted? the ND and PFD of the 737NG having precisely the problems described above.
For example airspeed below bugged airspeed on idle descent, instinct made me raise the nose a bit finding out the error got worse and thus lowering the nose.
I also had a problem identifying the flying attitude which I save for later.
After a year talking to people about it made me clear there are quite a lot of people having difficulties with it. Althoug one can say the higher numbers have to be on top as is altitude presented, I would say the result of an action should be presented. To make myself clear: pulling the nose up, I would gain altitude and lose airspeed. Having the aispeed indicator upside down this would result in the both the horizon bar, altitude and airspeed tape to move down.
The above post mentioned something about a relation between speed and throttle position. In my view this would still aply with the airspeed tape upside down. Adding thrust in a trimmed airplane you will see the nose rise, gain altitude and long term the speed will establish lower than the the level flight steady state value, so still the both tapes and the horizon will move down.. In underwing engined airplanes like 737 this speed effect will be fare more pronounced. (try a go-around without touching the flying controls...).
Another difficult thing with the speed tape is that the needle is fixed in the middle of the instrument and the scale moving past the needle. Imagine your car where the needle of the speed indicator is fixed on the twelve a clock position and the dial is turning behind it. This way you realy have to look at the number behind the needle to know how fast you are driving.
This makes for me perfectly clear how important the speed bug is. Cause without it you would not have a reference and everytime you look at the speed tape have to make an interpretation of your speed. (try and fly in the simulator without it or set by purpose a random number too high or low. It takes you some very long seconds to notice!)
To make it more difficult the designer presents all kind of yellow and red stripes around the speed tape, both on the low speed as on the high speed side which can all be visible during approach phase of flight.
In a round clock an experienced pilot will not only notice the speed bug, but from reference know where approx the needle needs to be, just as you know in your car in which position the needle should be for the legal highway limit, think about it.....
Then another thing about the attitude indicator an interpretation problems. Looking at an old fashioned attitude indicator one can tell which part of the indicator is part of the airplane structure and which part is the moving artificial horizon. Putting yourself or mother nature in an unnatural position you know immidiatly which way to roll to get wings level. As the parts of the indicator which move together with the airplane (and you inside) are immediatly clear, so is the action recquired to move to wings level.
Now take a look at the PFD of the 737ng. Sit in the cockpit before takeoff and tell me which lines(figures, etc) stay fixed, and which will move with the horizon. I'll bet you got some wrong. ( in straight and level flight this quistion will ALWAYS make people the aircraft bank just to see, because they cannot tell!!!)
This makes unusual attitude recognition more difficult then it need to be....
But yes, I learned to fly it. So what was my point exactly?
Just to let me know how bad my english is.....
About a year ago I made my way into the glass cockpit. Beforehand I was flying in the military flying with high performance classical instrumented airplanes and helicopters.
In the beginning it took me quite some time to interpreted? the ND and PFD of the 737NG having precisely the problems described above.
For example airspeed below bugged airspeed on idle descent, instinct made me raise the nose a bit finding out the error got worse and thus lowering the nose.
I also had a problem identifying the flying attitude which I save for later.
After a year talking to people about it made me clear there are quite a lot of people having difficulties with it. Althoug one can say the higher numbers have to be on top as is altitude presented, I would say the result of an action should be presented. To make myself clear: pulling the nose up, I would gain altitude and lose airspeed. Having the aispeed indicator upside down this would result in the both the horizon bar, altitude and airspeed tape to move down.
The above post mentioned something about a relation between speed and throttle position. In my view this would still aply with the airspeed tape upside down. Adding thrust in a trimmed airplane you will see the nose rise, gain altitude and long term the speed will establish lower than the the level flight steady state value, so still the both tapes and the horizon will move down.. In underwing engined airplanes like 737 this speed effect will be fare more pronounced. (try a go-around without touching the flying controls...).
Another difficult thing with the speed tape is that the needle is fixed in the middle of the instrument and the scale moving past the needle. Imagine your car where the needle of the speed indicator is fixed on the twelve a clock position and the dial is turning behind it. This way you realy have to look at the number behind the needle to know how fast you are driving.
This makes for me perfectly clear how important the speed bug is. Cause without it you would not have a reference and everytime you look at the speed tape have to make an interpretation of your speed. (try and fly in the simulator without it or set by purpose a random number too high or low. It takes you some very long seconds to notice!)
To make it more difficult the designer presents all kind of yellow and red stripes around the speed tape, both on the low speed as on the high speed side which can all be visible during approach phase of flight.
In a round clock an experienced pilot will not only notice the speed bug, but from reference know where approx the needle needs to be, just as you know in your car in which position the needle should be for the legal highway limit, think about it.....
Then another thing about the attitude indicator an interpretation problems. Looking at an old fashioned attitude indicator one can tell which part of the indicator is part of the airplane structure and which part is the moving artificial horizon. Putting yourself or mother nature in an unnatural position you know immidiatly which way to roll to get wings level. As the parts of the indicator which move together with the airplane (and you inside) are immediatly clear, so is the action recquired to move to wings level.
Now take a look at the PFD of the 737ng. Sit in the cockpit before takeoff and tell me which lines(figures, etc) stay fixed, and which will move with the horizon. I'll bet you got some wrong. ( in straight and level flight this quistion will ALWAYS make people the aircraft bank just to see, because they cannot tell!!!)
This makes unusual attitude recognition more difficult then it need to be....
But yes, I learned to fly it. So what was my point exactly?
Just to let me know how bad my english is.....
Last edited by have another coffee; 11th Sep 2002 at 17:42.
Guest
Posts: n/a
hi have another coffee,
your english is just fine,in fact i think its better than my ability to navigate around this site!
Which brings me to your 2nd point,that is,what is your point?!!
well i think the point is that,with enough practice and experience the human mind can become quite adept at handling even "Unergonomically"designed equipment--after all thats what has been happening all these years.
But a combination of low experience,hi stress,and adverse envoronmental factors,can still set up a situation where only an ergonomic design might stand between just "hair raizing" or "career ending error"
And till the time low experience,hi stress.... and/or human operators continue to exist we need to work towards recognizing problem areas and finding workable solutions
Your examples about the disadvantages of "Digital" vs "Analog" displays are very interesting.
i thing the challenge in designing an Ergonimic Glass cockpit PFD is in trying to put all the information in one place.i think thats why they have had to cut down on the analogues.But i think more thought and work is needed in this area.
i suspect progress wil be incrimental.
Giving consideration to"inverting the speed tape" idea could be a step in that direction,especially since i cant offhand thing of any adverse factors.
nightbird
your english is just fine,in fact i think its better than my ability to navigate around this site!
Which brings me to your 2nd point,that is,what is your point?!!
well i think the point is that,with enough practice and experience the human mind can become quite adept at handling even "Unergonomically"designed equipment--after all thats what has been happening all these years.
But a combination of low experience,hi stress,and adverse envoronmental factors,can still set up a situation where only an ergonomic design might stand between just "hair raizing" or "career ending error"
And till the time low experience,hi stress.... and/or human operators continue to exist we need to work towards recognizing problem areas and finding workable solutions
Your examples about the disadvantages of "Digital" vs "Analog" displays are very interesting.
i thing the challenge in designing an Ergonimic Glass cockpit PFD is in trying to put all the information in one place.i think thats why they have had to cut down on the analogues.But i think more thought and work is needed in this area.
i suspect progress wil be incrimental.
Giving consideration to"inverting the speed tape" idea could be a step in that direction,especially since i cant offhand thing of any adverse factors.
nightbird
Guest
Posts: n/a
A320 sidestick has autotrim
have another coffee,
About your reference to the tendency for the nose to rise when thrust is added for a Go-Around, and the A/C not re-trimmed.
That is definatly true of the 737-200.
i remember having to hold the yoke mounted trim switch forward for quite a long "Burst"(quite like a forward gun switch---oh i so loved that machine!)in case of a Go-Around.
The A320 remember is a "fly-by-wire" machine.
the side-stick has auto trim,and she is designed to maintain "1g" flight.
So she pretty much flies where you point her(or the stick) and there are no large control forces on the stick to give you any additional cues.
It is actually a LOT like a computer Game.
And in a computer game arn't the biggest cues that you use to fly,
"visual in-puts" from your displays,rather than the "feel" of your controls?
So imagine how easy it can be( for someone just transitioning from a conventional A/C)during Go- around to do a slower than normal rotation OR under rotation to "Go Around attitude" and set off a dangerous chain of events.
As the thrust comes in and the A/C starts accelerating,the red VFE barberpole starts to move down.
Forward stick to avoid this RED is a very possible human reaction.
Once the speed goes into the Band CRC(continous repetetive chime)sounds drowning out Cockpit communications and creating even more stress.
With a nose down att. of even just a few degrees, at around 1000 agl(above ground)there is very little time for anyone to break out of this disorentation.
Anyway, next week i have my 6 monthly visit to the Simulator,so will try out this scenario again,and get back to you.
Also looking forward to educating myself, with comments from other A320 drivers.
i cant find the link to that accident report anymore,can someone point me to it please.
nightbird
About your reference to the tendency for the nose to rise when thrust is added for a Go-Around, and the A/C not re-trimmed.
That is definatly true of the 737-200.
i remember having to hold the yoke mounted trim switch forward for quite a long "Burst"(quite like a forward gun switch---oh i so loved that machine!)in case of a Go-Around.
The A320 remember is a "fly-by-wire" machine.
the side-stick has auto trim,and she is designed to maintain "1g" flight.
So she pretty much flies where you point her(or the stick) and there are no large control forces on the stick to give you any additional cues.
It is actually a LOT like a computer Game.
And in a computer game arn't the biggest cues that you use to fly,
"visual in-puts" from your displays,rather than the "feel" of your controls?
So imagine how easy it can be( for someone just transitioning from a conventional A/C)during Go- around to do a slower than normal rotation OR under rotation to "Go Around attitude" and set off a dangerous chain of events.
As the thrust comes in and the A/C starts accelerating,the red VFE barberpole starts to move down.
Forward stick to avoid this RED is a very possible human reaction.
Once the speed goes into the Band CRC(continous repetetive chime)sounds drowning out Cockpit communications and creating even more stress.
With a nose down att. of even just a few degrees, at around 1000 agl(above ground)there is very little time for anyone to break out of this disorentation.
Anyway, next week i have my 6 monthly visit to the Simulator,so will try out this scenario again,and get back to you.
Also looking forward to educating myself, with comments from other A320 drivers.
i cant find the link to that accident report anymore,can someone point me to it please.
nightbird
Join Date: Dec 1998
Location: England
Posts: 242
Likes: 0
Received 0 Likes
on
0 Posts
GF072 Crash Report
http://www.bahrainairport.com/gf072f...nformation.htm
- Factual info only
http://www.bahrainairport.com/GF072i...tionreport.htm
- Accident Report Menu (all sections in pdf)
- Factual info only
http://www.bahrainairport.com/GF072i...tionreport.htm
- Accident Report Menu (all sections in pdf)
Guest
Posts: n/a
Thanks Overtalk
hi overtalk,
thanks a lot for setting up that link to the GF-072 Accident Investigation Report.
The more i delve into it,the more i am convinced that VFE (Flap OverSpeed) Red Barber pole,coupled with Continous Master Caution Warning,was the final causal factor to this sad event.
i think the US Naval Aerospace Medical Research Lab folks have a lot of "Naval Flying Baggage",and are essentially barking up the wrong tree.
They have based there findings on the assumption that neither of the pilots was even glancing at the PFDs
Whatever else Airline pilots might refer to(or not) for flying,they definatly dont fly looking out of the window in a dark moonless night.
The report mentions information overload(the Loud Master Caution because of flap speed exeedance i am sure added to it)
Looks to me that they have covered all issues except design issues.
But even they mention the need to improve visual cues provided the PFD in passing.
nightbird
thanks a lot for setting up that link to the GF-072 Accident Investigation Report.
The more i delve into it,the more i am convinced that VFE (Flap OverSpeed) Red Barber pole,coupled with Continous Master Caution Warning,was the final causal factor to this sad event.
i think the US Naval Aerospace Medical Research Lab folks have a lot of "Naval Flying Baggage",and are essentially barking up the wrong tree.
They have based there findings on the assumption that neither of the pilots was even glancing at the PFDs
Whatever else Airline pilots might refer to(or not) for flying,they definatly dont fly looking out of the window in a dark moonless night.
The report mentions information overload(the Loud Master Caution because of flap speed exeedance i am sure added to it)
Looks to me that they have covered all issues except design issues.
But even they mention the need to improve visual cues provided the PFD in passing.
nightbird
Join Date: Dec 1998
Location: England
Posts: 242
Likes: 0
Received 0 Likes
on
0 Posts
nightbird
Does the speedtape come down from the top on both Airbus and Boeing? I thought it rose from the bottom on most Boeings.
I have some interest in this because I originally pointed at the pitch up somatogravic illusion as being likely causal in GF072. I'd not be at all happy if that had given Airbus a sidestep to avoid another hazard that's still extant. Managing Editor of Air Safety Week shares that concern - so if you manage to turn up anything further, you can pass it to him at [email protected].
Does the speedtape come down from the top on both Airbus and Boeing? I thought it rose from the bottom on most Boeings.
I have some interest in this because I originally pointed at the pitch up somatogravic illusion as being likely causal in GF072. I'd not be at all happy if that had given Airbus a sidestep to avoid another hazard that's still extant. Managing Editor of Air Safety Week shares that concern - so if you manage to turn up anything further, you can pass it to him at [email protected].
Guest
Posts: n/a
any 777drivers out there?
Hi OVERTALK
i havnt yet had a chance to check up on the Speed Tape on the Boeing Glass Cockpits.
i flew the B737-200, and the only tape that had was of the adhesive kind holding stuff togather!
Hope some Boeing Jock reading this enlightens us.(HELP WANTED!)
otherwise will ask the first one i meet next,and let you know.
Captain Stable seems to think that it is the industry norm.
Once again i would like to repeat my view that Unlike Military Pilots, Present generation of Airline Pilots are quite used to ignoring "feel" and "Outside reference" to the horizon.
They might ignore the PFD for short spans of time due preoccupation,but never for long.
BUT any positive flight control inputs to change A/C ATTITUDE is invariably done with sole referance to the PFD.(we dont know HOW TO any other way)
Even when we fly the machine "Visually",visual cues are only used, to laterally Align A/C with the Runway Centre-line and Touch Down Zone.
What the "inner ear" says,cant make both of them completely ignore the PFD,thats just not how it works anymore.
Also the contention that the PFD is located off to the left and that all the pre-occupation about flaps and Landing Gear were towards the Central Panel,and thus they failed to moniter the PFD,to me appears to be flawed.
A320 drivers can quite easily get almost all the neccessary Information required at any stage of flight while looking just at the PFD the ND(Nav Display) and the upper and lower ECAMs.
Indeed that is how they are trained to fly from Day one.
Looking at any ONE of these 4 Displays, still keeps the other 3 in easy "Peripheral Vision".
Of-course extent of "Peripheral Vision" is a function of "experience on type" and "stress levels existing"
My Contention remains that "not refering to the PFD" did not cause this Accident.
"Not being able to correctly comprehend the information on the PFD speed tape,due to poor design " caused it
regards,
nightbird
OVERTALK,
i am still getting the hang of "Cyber space"
So it might take me a while to figure out how to forward all this to
[email protected]
would really appreciate it if you could do it for me.
As they say " if ONE Human mind misread that PFD once, potentially ANY human mind can misread it again"
i think we should try to nail this MINDTRAP before it claims other victims.
Thanks again
nightbird
i havnt yet had a chance to check up on the Speed Tape on the Boeing Glass Cockpits.
i flew the B737-200, and the only tape that had was of the adhesive kind holding stuff togather!
Hope some Boeing Jock reading this enlightens us.(HELP WANTED!)
otherwise will ask the first one i meet next,and let you know.
Captain Stable seems to think that it is the industry norm.
Once again i would like to repeat my view that Unlike Military Pilots, Present generation of Airline Pilots are quite used to ignoring "feel" and "Outside reference" to the horizon.
They might ignore the PFD for short spans of time due preoccupation,but never for long.
BUT any positive flight control inputs to change A/C ATTITUDE is invariably done with sole referance to the PFD.(we dont know HOW TO any other way)
Even when we fly the machine "Visually",visual cues are only used, to laterally Align A/C with the Runway Centre-line and Touch Down Zone.
What the "inner ear" says,cant make both of them completely ignore the PFD,thats just not how it works anymore.
Also the contention that the PFD is located off to the left and that all the pre-occupation about flaps and Landing Gear were towards the Central Panel,and thus they failed to moniter the PFD,to me appears to be flawed.
A320 drivers can quite easily get almost all the neccessary Information required at any stage of flight while looking just at the PFD the ND(Nav Display) and the upper and lower ECAMs.
Indeed that is how they are trained to fly from Day one.
Looking at any ONE of these 4 Displays, still keeps the other 3 in easy "Peripheral Vision".
Of-course extent of "Peripheral Vision" is a function of "experience on type" and "stress levels existing"
My Contention remains that "not refering to the PFD" did not cause this Accident.
"Not being able to correctly comprehend the information on the PFD speed tape,due to poor design " caused it
regards,
nightbird
OVERTALK,
i am still getting the hang of "Cyber space"
So it might take me a while to figure out how to forward all this to
[email protected]
would really appreciate it if you could do it for me.
As they say " if ONE Human mind misread that PFD once, potentially ANY human mind can misread it again"
i think we should try to nail this MINDTRAP before it claims other victims.
Thanks again
nightbird
Join Date: Jun 2000
Location: netherlands, amsterdam
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
Boeing speed tape has the higher speeds on the upper side of the PFD (737NG) and I presume it will be all the same for the other boeing products.
As I have no experience at all with Airbus products I cannot comment on that. However I think most of the comments regarding the presentations in the glass cockpit apply to both of them.
My opinion is that position awareness on these aircraft is extremely high. If the pilots pay a little bit of attention its almost impossible to fly into the ground (EGPWS, map display, LNAV etc). The manufactures have put a lot of effort into avoiding CFIT incidents. Still about 25% of all aviation accidents are due to loss of control ! And If I look at the improvements made on that aspect in the cockpit its very very poor. The instruments look nice in the glass cockpit but they are basicly the same as 50 years ago. Fly by wire made some protection possible to keep the aircraft within the "envelope" but where in the envelope the aircraft is and where its going performance wise is very difficult to predict. Particulary as the cockpit windows are very small, wind and engine noise have almost disappeared and (not for boeing aircraft) control forces are gone.
I fully agree with Nightbird that the chosen locations of instruments is not the best. And many times your eyes are swerving through the cockpit to look for some indication, be it flap position, engine power or outside reference etc...
There have to be some scientific research been done in the past to come to the present situation. If anybody can point me to some I'd be greatfull. Just to see what arguments they came up with.
Finaly I'd like to tell about a occurence that happened a few months ago during an ils approach which demonstrates some of the problems Nightbird is worried about.
Cat 1 Ils approach with cloudbase around minima. Autopilot and autothrottle engaged. In the GPWS minimums call I called the runway. Captain disengaged AP but instead of disengaging AT he pushed GA buttons. F/D into go around mode and thrust increase. Upon recognising his mistake disengaged a/t. Now the speedbug was set for GA and thrust not stabilised for approach. This caused lots of confusing both by him and me. All the "reference values" were gone. FAS was somewehere between displayed speedbug and displayed Vref on speed tape. It was just impossible to tell with an eye glance wether speed was high or low. Thrust was pulled back so far in the reaction of the forward movement of the thrust levers that it was way beyond wat one would call stabilized setting for final approach. When I called for power the captain said something about speed being too high, which in fact was already approaching Vref and by the look of the trend vector was not increasing. Although he adjusted a fare amount of power it was nowhere enough and the only option left was making the Go around after all. After a further uneventfull landing we discussed the event. He told me he was fully confinced about the speed being too high as referenced the speed against the speed bug. He also admitted although he thought power was set he never really looked at the actual N1. When I told him the speed bug was still about 15 knots above our calculated FAS and this was caused by the GA mode of the FD and our actual speed just before the actual go-around was already Vref he admitted he was completely confused about it.
This just to refer to the last comment Nightbird made about any human misreading the speedtape......
As I have no experience at all with Airbus products I cannot comment on that. However I think most of the comments regarding the presentations in the glass cockpit apply to both of them.
My opinion is that position awareness on these aircraft is extremely high. If the pilots pay a little bit of attention its almost impossible to fly into the ground (EGPWS, map display, LNAV etc). The manufactures have put a lot of effort into avoiding CFIT incidents. Still about 25% of all aviation accidents are due to loss of control ! And If I look at the improvements made on that aspect in the cockpit its very very poor. The instruments look nice in the glass cockpit but they are basicly the same as 50 years ago. Fly by wire made some protection possible to keep the aircraft within the "envelope" but where in the envelope the aircraft is and where its going performance wise is very difficult to predict. Particulary as the cockpit windows are very small, wind and engine noise have almost disappeared and (not for boeing aircraft) control forces are gone.
I fully agree with Nightbird that the chosen locations of instruments is not the best. And many times your eyes are swerving through the cockpit to look for some indication, be it flap position, engine power or outside reference etc...
There have to be some scientific research been done in the past to come to the present situation. If anybody can point me to some I'd be greatfull. Just to see what arguments they came up with.
Finaly I'd like to tell about a occurence that happened a few months ago during an ils approach which demonstrates some of the problems Nightbird is worried about.
Cat 1 Ils approach with cloudbase around minima. Autopilot and autothrottle engaged. In the GPWS minimums call I called the runway. Captain disengaged AP but instead of disengaging AT he pushed GA buttons. F/D into go around mode and thrust increase. Upon recognising his mistake disengaged a/t. Now the speedbug was set for GA and thrust not stabilised for approach. This caused lots of confusing both by him and me. All the "reference values" were gone. FAS was somewehere between displayed speedbug and displayed Vref on speed tape. It was just impossible to tell with an eye glance wether speed was high or low. Thrust was pulled back so far in the reaction of the forward movement of the thrust levers that it was way beyond wat one would call stabilized setting for final approach. When I called for power the captain said something about speed being too high, which in fact was already approaching Vref and by the look of the trend vector was not increasing. Although he adjusted a fare amount of power it was nowhere enough and the only option left was making the Go around after all. After a further uneventfull landing we discussed the event. He told me he was fully confinced about the speed being too high as referenced the speed against the speed bug. He also admitted although he thought power was set he never really looked at the actual N1. When I told him the speed bug was still about 15 knots above our calculated FAS and this was caused by the GA mode of the FD and our actual speed just before the actual go-around was already Vref he admitted he was completely confused about it.
This just to refer to the last comment Nightbird made about any human misreading the speedtape......
Interesting: If any of our Airbus pilots have discussed this outside the cockpit, I doubt that many of us would have understood small fragments of this topic.
By the way, the 757 was designed with round gauges for engine instruments and the six primary flight instruments and standby gauges, from what I remember.
Southwest Airlines, from what I've seen in photographs, had Boeing design their 737 NG CRT screens to show 'round gauge' flt. instruments, if I remember correctly. And for safety standardization, the Southwest pilots use very little of the later models "magic", according to what some of their captains have told me.
How would NASA's Ames research or university research centers compare and rank the A-320 vs. old technology flt instrument displays, based on intuitive perception and safety, or is this topic too abstract, knowing that other factors can have a strong influence, as pointed out by previous remarks on this subject?
I'm hoping to one day be more open-minded about the A-320-it is slowly replacing our old planes and there is almost zero chance that we will ever order any 737s, unless a leasing company or the manufacturer practically gives them and the simulators away far below cost-something like Airbus marketing tactics, excluding the very high replacement part costs.
By the way, the 757 was designed with round gauges for engine instruments and the six primary flight instruments and standby gauges, from what I remember.
Southwest Airlines, from what I've seen in photographs, had Boeing design their 737 NG CRT screens to show 'round gauge' flt. instruments, if I remember correctly. And for safety standardization, the Southwest pilots use very little of the later models "magic", according to what some of their captains have told me.
How would NASA's Ames research or university research centers compare and rank the A-320 vs. old technology flt instrument displays, based on intuitive perception and safety, or is this topic too abstract, knowing that other factors can have a strong influence, as pointed out by previous remarks on this subject?
I'm hoping to one day be more open-minded about the A-320-it is slowly replacing our old planes and there is almost zero chance that we will ever order any 737s, unless a leasing company or the manufacturer practically gives them and the simulators away far below cost-something like Airbus marketing tactics, excluding the very high replacement part costs.
Guest
Posts: n/a
Just tried it in the Simulator
i just got back from my annual Instrument Rating Check ride on the A320 simulator.
So just a few points
1. it takes very little time to accelerate to Flap overspeed at TOGA and pitch att. 5 degrees.
once she gets there the CRC continuos Chime and the Red Overspeed barberpole are the 2 things that hold your attention compellingly.
2. regular visits to 6 axis simulators are very effective in making Airline pilots generally imune to spatial disorientaion.
3.the A320 Auto Thrust system is such that.Pilots have very little practice of managing thrust by moving the thrust levers.
they are much more likely(as compared to other A/C, in terms of speed management) to use the sidestick in response to any PFD induced perception of over/under speed.
Hence there is a need to take a fresh look at how the Speed tape is orientated.
So just a few points
1. it takes very little time to accelerate to Flap overspeed at TOGA and pitch att. 5 degrees.
once she gets there the CRC continuos Chime and the Red Overspeed barberpole are the 2 things that hold your attention compellingly.
2. regular visits to 6 axis simulators are very effective in making Airline pilots generally imune to spatial disorientaion.
3.the A320 Auto Thrust system is such that.Pilots have very little practice of managing thrust by moving the thrust levers.
they are much more likely(as compared to other A/C, in terms of speed management) to use the sidestick in response to any PFD induced perception of over/under speed.
Hence there is a need to take a fresh look at how the Speed tape is orientated.
OK Airbus people-in comparison to the vertical tape airspeed display on older planes such as Lockheed 1011, C-141 and C-5 transports, how is the Airbus different, or is pilot perception and interpretation about the same, except for the Lockheed's probable lack of a trend vector, if you call it that? Air Force pilots seem to have said that they got used to the vertical tape for most flight (except for ADI/HSI) and engine instruments quickly.
Guest
Posts: n/a
Trend Vector would show which way to push thrust levers!
Hey Ignition Override
i think the A320 speed tape has just been blindly following the industry trend so far.
i just saw a couple of illustrations in the book "Human Factors" by Capt Hawkins, and they also depict the higher speeds on top of the tape.
Its just that in older aircraft types,this does not appear to have had any serious adverse consequences.
Probably because of the fact that the thrust management was still done pretty much "hands on".
On the A320,the auto-thrust system is virtually "Hands-Off".
Essentially Pilots practice just one simulator exercise every 6 months of actual "hands on" speed management.
The MEL(Minimum Equip List) does not permit despatch with Auto thrust Unservisable.
Also level of change in engine noise during approach power settings is not very perceptable from the cockpit.
All these factors can lead to a situation where pilot awareness of actual "aircraft energy level" can be degraded.
Atleast 2 accidents on the A320/A330 can be attributed to lack of awareness of a/c energy level(low energy warning is now being incorporated)
The A320 has very comprehensive "flight envelope protection"
but she is not immune from being flown into terrain(CFIT).
What concerns me is that, in the case of GF072 was the A/C unwittingly pointed into the sea as a result of "Information Overload" Originating from the Aural CRC Warning and the red Overspeed Barber pole Coming down from the top.
As the report says this rather low priority overspeed situation occupied the Flt. crews attention,to the exclusion of the bigger threat posed by their proximity to terrain.
the investigation even examined the posibility of inadvertent forward push on sidestick while trying to reach for the "emergency cancel" on the central panel,and ruled it out.
i thing the investigation is trying to avoid opening "a can of worms" by not going into the possible role played by design deficiencies.
But as Capt Hawkins says Human errors can be located anywhere in the chain streching from the "operator" right back to the "designer".
By-the-Way if the Speed tape were inverted,the Trend Vectors(or Arrows as they are also called) would reflect the correct direction in which to move the Thrust Levers!
So in case of flap overspeed not only would the Red Barberpole coming up from the bottom urge a "natural" stick back reaction, but also a downward trend vector would ask for a Thrust lever back response!
i think the A320 speed tape has just been blindly following the industry trend so far.
i just saw a couple of illustrations in the book "Human Factors" by Capt Hawkins, and they also depict the higher speeds on top of the tape.
Its just that in older aircraft types,this does not appear to have had any serious adverse consequences.
Probably because of the fact that the thrust management was still done pretty much "hands on".
On the A320,the auto-thrust system is virtually "Hands-Off".
Essentially Pilots practice just one simulator exercise every 6 months of actual "hands on" speed management.
The MEL(Minimum Equip List) does not permit despatch with Auto thrust Unservisable.
Also level of change in engine noise during approach power settings is not very perceptable from the cockpit.
All these factors can lead to a situation where pilot awareness of actual "aircraft energy level" can be degraded.
Atleast 2 accidents on the A320/A330 can be attributed to lack of awareness of a/c energy level(low energy warning is now being incorporated)
The A320 has very comprehensive "flight envelope protection"
but she is not immune from being flown into terrain(CFIT).
What concerns me is that, in the case of GF072 was the A/C unwittingly pointed into the sea as a result of "Information Overload" Originating from the Aural CRC Warning and the red Overspeed Barber pole Coming down from the top.
As the report says this rather low priority overspeed situation occupied the Flt. crews attention,to the exclusion of the bigger threat posed by their proximity to terrain.
the investigation even examined the posibility of inadvertent forward push on sidestick while trying to reach for the "emergency cancel" on the central panel,and ruled it out.
i thing the investigation is trying to avoid opening "a can of worms" by not going into the possible role played by design deficiencies.
But as Capt Hawkins says Human errors can be located anywhere in the chain streching from the "operator" right back to the "designer".
By-the-Way if the Speed tape were inverted,the Trend Vectors(or Arrows as they are also called) would reflect the correct direction in which to move the Thrust Levers!
So in case of flap overspeed not only would the Red Barberpole coming up from the bottom urge a "natural" stick back reaction, but also a downward trend vector would ask for a Thrust lever back response!
Join Date: May 2000
Location: Camp X-Ray
Posts: 2,135
Likes: 0
Received 0 Likes
on
0 Posts
Nightbird - I hear what you're saying but to suggest that manual thrust control is a 6-monthly sim exercise is perhaps making excuses for operators laziness. There is no prohibition in our MEL on departing with A/THR inop and it is encouraged that crew operate the aircraft fully manually when weather and air traffic cirumstances permit. True, there is limited aural feedback for engine thrust levels, particularly if wearing ANR headsets, but the E/WD is only a glance away and will tell you exactly what the engines are doing. Regular A/THR out practice will give crews the confidence to disconnect the A/THR and set meaningful power settings when the automation gets out of step. In the GF case it is futile to blame speed tape errors for the accident. Any pilot with hands-on experience should appreciate that in the event of an overspeed, pulling the stick back rather than pushing forward is the correct response, and in the event of a GPWS 'pull up' pulling back is the only response. The best way to prevent future occurences of this type of accident is to implement an operational policy which ensures stabilised approaches, rather than redesign the speed tape and hope that that covers the full range of destabilised approaches and badly flown go-arounds.
Guest
Posts: n/a
anyone out there who is familiar with "Human Factors in Flight"?
Hand Solo,
So you are saying that all that needs to be done to acheive a zero accident rate is ensure that flt crews follow SOPs(and also get them to practice hands on "raw data" flying)
i dont disagree at all.That is how it works in most "Good Airlines".
And inculcating a good "work culture" is a worthy and attainable goal.
But that does not mean that we stop, looking at ways of improving the design of Cockpit Displays(and Controls)
In New Generation "Glass Cockpit" machines the "Man Machine" interface is far from perfect.
My endeavour in this post , has been to bring attention to only one such display.
Most of my effort has been in trying to explain the basics, which form the background(including what i suspect is an actual accident
in which this aspect played a central role)
we could lump it under the "just another CFIT,caused by non adhereance to SOPs."
But will we have moved any closer to making the flight deck safer for a crew of the future who might be following SOPs, but are faced with a information overload situation created not by their own acts,but by Environmental or Mechanical factors?
So you are saying that all that needs to be done to acheive a zero accident rate is ensure that flt crews follow SOPs(and also get them to practice hands on "raw data" flying)
i dont disagree at all.That is how it works in most "Good Airlines".
And inculcating a good "work culture" is a worthy and attainable goal.
But that does not mean that we stop, looking at ways of improving the design of Cockpit Displays(and Controls)
In New Generation "Glass Cockpit" machines the "Man Machine" interface is far from perfect.
My endeavour in this post , has been to bring attention to only one such display.
Most of my effort has been in trying to explain the basics, which form the background(including what i suspect is an actual accident
in which this aspect played a central role)
we could lump it under the "just another CFIT,caused by non adhereance to SOPs."
But will we have moved any closer to making the flight deck safer for a crew of the future who might be following SOPs, but are faced with a information overload situation created not by their own acts,but by Environmental or Mechanical factors?
Join Date: Mar 2001
Location: London,,Great Britain
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
I fly the 777, which has fairly similar EFIS.
I think that ‘tapes’ are not an ideal way of presenting data that has to be understood rapidly and are a bit of a ‘cop out’ from the manufacturers.
I find the altitude and airspeed strips much less easy to interpret than their round cousins, especially in a dynamic situation.
The problem stems, I think, from having a static pointer on a moving scale that is many times larger than the display itself. Compare this to having a pointer on a dial (or even a strip) that shows the whole scale. The absolute position of the pointer always has meaning, as does the direction of its motion, and these parameters can be quickly assessed without having to mentally process a load of numbers.
A while back I flew the 737 and would regularly step from a –200 (analogue dials) to a –400 (glass cockpit with tapes) and vice-versa during a single day. There were many faults with both styles of presentation: the –200, for example, suffering from ‘shotgun’ placement of instruments. However, I found the –200 easier to fly accurately, especially on the latter stages of the (visual) approach when most of your attention was directed outside the cockpit.
I feel we are in a temporary situation, in that EFIS is now cheaper and more reliable than ‘analogue’ instrumentation but system integration and ‘legacy’ requirements do not allow us (as yet) to be given the ‘path through the sky’ or ‘synthetic visual’ presentations. I fear this has left us with the worst of both worlds (the company I work for found, from real-life data, that situational awareness was much more likely to be compromised in a glass cockpit than a conventional one).
Back to the speed-tape issue. I think an enhancement to current displays would be to have the whole speed range displayed at once with the pointer moving up and down. This would still be combined with trend vectors, manoeuvring margins etc. and if the scale ended up too compressed, the area in which you were operating could be magnified and made to move in the opposite sense to the pointer. Personally I find most electronic airspeed displays far too sensitive (I can’t fly to within a knot, five maybe on a good day), especially on approach where they bounce all over the place. On the 777 this interacts badly with the autothrottle (although I realise this has nothing to do with the display, rather the rapidly changing airspeed data) and makes the power go up and down like a yo-yo. The 777 is 200ft wide, about as long and weighs c.200t on approach. Rapid, small, local variations of air movement make hardly any difference to the overall performance of the airframe, yet they are displayed with great fidelity. This unfortunately distresses some people!
In summary, I would say that I am unhappy with the present style of EFIS presentation in large transport aeroplanes, and I think we should be looking closely at what is happening in the bizjet/GA/military sectors, as they are less constrained by what has gone before.
I think that ‘tapes’ are not an ideal way of presenting data that has to be understood rapidly and are a bit of a ‘cop out’ from the manufacturers.
I find the altitude and airspeed strips much less easy to interpret than their round cousins, especially in a dynamic situation.
The problem stems, I think, from having a static pointer on a moving scale that is many times larger than the display itself. Compare this to having a pointer on a dial (or even a strip) that shows the whole scale. The absolute position of the pointer always has meaning, as does the direction of its motion, and these parameters can be quickly assessed without having to mentally process a load of numbers.
A while back I flew the 737 and would regularly step from a –200 (analogue dials) to a –400 (glass cockpit with tapes) and vice-versa during a single day. There were many faults with both styles of presentation: the –200, for example, suffering from ‘shotgun’ placement of instruments. However, I found the –200 easier to fly accurately, especially on the latter stages of the (visual) approach when most of your attention was directed outside the cockpit.
I feel we are in a temporary situation, in that EFIS is now cheaper and more reliable than ‘analogue’ instrumentation but system integration and ‘legacy’ requirements do not allow us (as yet) to be given the ‘path through the sky’ or ‘synthetic visual’ presentations. I fear this has left us with the worst of both worlds (the company I work for found, from real-life data, that situational awareness was much more likely to be compromised in a glass cockpit than a conventional one).
Back to the speed-tape issue. I think an enhancement to current displays would be to have the whole speed range displayed at once with the pointer moving up and down. This would still be combined with trend vectors, manoeuvring margins etc. and if the scale ended up too compressed, the area in which you were operating could be magnified and made to move in the opposite sense to the pointer. Personally I find most electronic airspeed displays far too sensitive (I can’t fly to within a knot, five maybe on a good day), especially on approach where they bounce all over the place. On the 777 this interacts badly with the autothrottle (although I realise this has nothing to do with the display, rather the rapidly changing airspeed data) and makes the power go up and down like a yo-yo. The 777 is 200ft wide, about as long and weighs c.200t on approach. Rapid, small, local variations of air movement make hardly any difference to the overall performance of the airframe, yet they are displayed with great fidelity. This unfortunately distresses some people!
In summary, I would say that I am unhappy with the present style of EFIS presentation in large transport aeroplanes, and I think we should be looking closely at what is happening in the bizjet/GA/military sectors, as they are less constrained by what has gone before.
