NTSB update on Asiana 214
As usual AirRabbit speaks words of wisdom. Back in the late 1980s I spent time with Boeing as they were developing the new CRT displays for the PFD on the Boeing 747-400. They experimented with a number of different presentations, round dial, tapes, different sizes, different colours, etc. and also the scales and sensitivities on each element of the displays and the relative sensitivities between them. The pilots involved were given a number of flying exercises, short routes that involved multiple turns and level-outs, etc. all ranging in difficulty. Then we, and the Boeing engineers, rated our performances and discussed preferences.
Some of the displays I found almost un-flyable, others were easy and intuitive. The final displays used by Boeing on the -400 PFD I found very easy to fly. I liked the tape presentations for speed and altitude but found the VSI too small. I also very much liked the way the FMA information was grouped at the top, the way speed commands and limitations were displayed, the large central ADI, and the colours used.
However, the thing I found hardest was to shed my personal preference for the round dial instruments that I had used for the previous 30years. It is very hard to separate basic ergonomic factors from learned personal preferences that have become ingrained from years of training and use. I am sure there is a huge amount of research information on the interesting topics that are being discussed in this thread which AirRabbit could direct us to.
Some of the displays I found almost un-flyable, others were easy and intuitive. The final displays used by Boeing on the -400 PFD I found very easy to fly. I liked the tape presentations for speed and altitude but found the VSI too small. I also very much liked the way the FMA information was grouped at the top, the way speed commands and limitations were displayed, the large central ADI, and the colours used.
However, the thing I found hardest was to shed my personal preference for the round dial instruments that I had used for the previous 30years. It is very hard to separate basic ergonomic factors from learned personal preferences that have become ingrained from years of training and use. I am sure there is a huge amount of research information on the interesting topics that are being discussed in this thread which AirRabbit could direct us to.
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Interesting stuff, the human factor cockpit ergonomics. Personally (totally a pre computer ager) I like to glance at a dial, needle position, rate of movement tell me all I need to know, the actual numbers are at times not impotrant. Most changed to oil pressure, temp etc I've encontered drew my attention because the needle was sitting in the wrong place. The Bell "Jetdanger" 206-B3 I instruct on has some glass instruments fitted and a digital TIT gauge. However apart from the number, it also has the running segments or bars in a radial around the gauge. After a few starts trying to interpret the numbers, I soon changed to watching the sweep if the segments, like a needle, rate and position tell me what I want to know. However having an exact number to look at in steady operation, is good. The glass MFD AI and HSI with coupled GPS data is good I will admit. It has speed and alt readouts right there on the sides of the displays but my very ingrained habit of scanning the other instruments, ASI, Altimeter etc, is too strong. It feels uncomfortable interpretting that info off the tape displays.
I recall the C5 Galaxy had some of the first tape cockpit displays and there were issues? One being the movement of the tape, is up an increase or decrease? To me with a fixed pointer, an upwards movement should be an increase?
The other point is so much talk of speed related to stalling? In the military when we taught stalling, speed had nothing to do with it, if there was buffet you were stalling, no buffet, no stall. Are we not associating speed with stalling too much? Yes speed is important but to so closely link speed and stalling? Most airliners have an AoA indicator, are the crew taught to use thyis in identifying an approaching stall? Do the MFD's start flashing somthing attention grabbing as crit alpha approaches?
I recall the C5 Galaxy had some of the first tape cockpit displays and there were issues? One being the movement of the tape, is up an increase or decrease? To me with a fixed pointer, an upwards movement should be an increase?
The other point is so much talk of speed related to stalling? In the military when we taught stalling, speed had nothing to do with it, if there was buffet you were stalling, no buffet, no stall. Are we not associating speed with stalling too much? Yes speed is important but to so closely link speed and stalling? Most airliners have an AoA indicator, are the crew taught to use thyis in identifying an approaching stall? Do the MFD's start flashing somthing attention grabbing as crit alpha approaches?
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This is another's pilot take on this topic: ...
The discussion has been about the presentation of airspeed in the scrolling "tape" format (as opposed to the big round dial of yesteryear). Nobody in this thread, including me, has raised any objections to the modern glass cockpits in general.
It is my opinion that glass cockpits dramatically improve on the way information is made available to pilots. I'm sure that would be the opinion of everybody on this thread.
But in the case of indicated airspeed (IAS), the presentation is significantly less effective, and I believe this fact has played a key role in the crashes of those 4 passenger aircraft since 2009 (Asiana 214 the most recent). (I believe the presentation of vertical speed (VS) is also less effective, but don't believe this was a factor in those crashes).
I believe that an habitual reliance on automation also played a key role, but this belief seems to be almost universally held, so I feel no need to dwell on that.
Another point you seem to be missing, by linking to that article, olasek, is that nobody has any difficulty with the speed tape when in the normal, low stress situation.
I have made the point many times now, that it is only when the chips are down that the differences between these two styles of presentation become significant.
For the 3 minutes that it took Air France 447 to fall to the ocean, the round dial airspeed indicators would have been pointing to the 1 o'clock position - if they had them. But unfortunately for them, they had the tapes. Perhaps someone here with Airbus experience can detail what those tapes would actually have been showing.
I can bet it was nothing like the simple, but big picture of a needle pointing at 1 o'clock.
... comparing modern aircraft speed indicator with a consumer digital watch is a sign of ignorance, only a non-pilot can make such a comparison.
The point of that particular exercise is to get you to examine what your brain does when you look at an analogue clock, because what it does then is very similar to what it does when glancing at an airspeed dial.
If you can't work it out for yourself, I will now tell you. Your brain makes an assessment of the angular separation between the pointer (or minute hand) and the particular datum of interest (the 12 o'clock position in the case of the ASI).
Human beings are extremely good at working with angles. That is, estimating angles and angular distances/separations and repeating angular displacements. This is an ability that evolution has bestowed upon us and refined over millions of years. This natural ability has been referred to by numerous posters to this thread, which brings me to this statement, by Volume:
The main issue of Human Factors is that there is not a single standardized human on this planet...
This means that it does not matter whether a pilot learnt to fly with a speed tape, or the old dial. Those millions of years of evolution still make it far easier for him to assess airspeed via the angular displacement of a pointer.
Look at this photo. Note the engine instruments. Only the top 4 sets are visible, but there are 6 sets of gauges on the King Air. Beechcraft, in their wisdom (or perhaps copying someone else), deliberately arranged the gauges so that the needles all point in the 8-10 o'clock position when the engines are in the normal, cruise power range.
Below the 4 visible sets of gauges are the fuel flow and oil temperature/pressure. Those gauges have also been arranged so that their pointers all point to the 8-10 o'clock position when everything is normal.
I have flown King Airs and can testify that, because of this deliberate gauge arrangement, it is extremely easy to assess that all is normal with both engines. We are not even in the cockpit of this King Air, but we can instantly see that all is well! We can also see a healthy airspeed!
Which brings me to my next point, which clearly illustrates just how poorly the tape communicates airspeed to us.
Airspeed, as we all know, is a very, very important and fundamental aspect of flight in our flying machines. In terms of importance, it is BIG. It could be said that airspeed is even more important than attitude.
But when we look at a typical in-flight photo of a glass cockpit instrument panel, we cannot tell whether the airspeed is healthy or not, because the central area of the tape display is so tiny. We can see the attitude very well, however, and this is as it should be.
Something as BIG as airspeed should be so communicative that it could clearly be seen in even a fuzzy photo.
If you can tell that the airspeed is healthy (or not) from a fuzzy photo, then you know you have the best and most appropriate presentation of airspeed. This is the case with attitude, so why not with airspeed?
Here is what AF447 would have seen with an electro-mechanical round dial:
https://images.search.yahoo.com/imag...fr=yfp-t-901-s
https://images.search.yahoo.com/imag...fr=yfp-t-901-s
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Wrong, very wrong. Every human is highly, highly "standardised". When it comes to how the human machine works and behaves, we are all, in fact, virtually identical.
the round dial airspeed indicators would have been pointing to the 1 o'clock position.
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. I think they were pretty sure that it is an unreliable (even senseless, or how they worded it "ridiculos") indication, so they would have ignored it anyway
And as far as Asiana crash - I very much doubt these pilots even once glanced in the direction of the airspeed, or even if they did their brain was simply shut out of processing any such info, so contention that a round dial would have saved them is a pure poppycock.
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Hi Bergerie1 – first, let me offer my most sincere “thanks” for the very nice compliment … and second, your comment that “It is very hard to separate basic ergonomic factors from learned personal preferences that have become ingrained from years of training and use” is another way of precisely saying the same point I was trying to make.
I am fully aware of (well … maybe not “fully aware, ” but certainly knowledgeable about…) the extent to which airplane cockpit designers go to provide complete and accurate information to the occupants of those cockpits – and, in addition to the amount of information provided, these professionals strive diligently to make that information easily recognizable and immediately useful to those pilots. As I have noted in many of my previous posts in this forum, in my somewhat sordid past, I’ve had the opportunity to see and work with, and for, some of the finest pilot instructors I’ve ever known – and in that process perhaps the most valuable concept to which I was introduced was to find a way to allow the student to use the preferences he/she has come to know and understand to perform any specific task.
The point I had to understand, and to which I had to be willing to commit, was that doing this caused my expenditure of time, effort, and awareness to “skyrocket.” While I readily acknowledge that it is certainly possible that I had to work harder at instructing than did my counterparts … it is equally true that the more I did it, the more I came to recognize that each of the instructors I observed and learned from, also worked very hard to achieve any notable success. The good thing was that when a student’s “light bulb” finally illuminated, I usually felt better than did the student! All of which is to say that ... when you recognize what the student has actually assimilated (not merely regurgitated) the satisfaction far outweighs any thought of "work"
The problem I see today is that instructors often wholly and absolutely depend on the training syllabus (i.e., the lesson plan) and, much to my chagrin and even greater disappointment, the training equipment itself, to “teach” the student what he/she needs to know. What instructors must come to understand is that a fully qualified pilot doesn’t just “happen” at the completion of a training “program” simply by having completed that program. Perhaps the 2 most important things a pilot instructor must know and must know how to address are the following:
1) The structure of a competent training program must include what a pilot must know, what skills a pilot must possess, and what rules a pilot must follow … and all of that has to fit into what that pilot can understand and use – and do so correctly … when things go as planned and when the plan goes askew (i.e., amiss, muddled, twisted, off-center, or just plain wrong); and
2) The flight simulator doesn’t “know” anything – and when such equipment is used without the direct involvement and oversight of a qualified, competent, and relatively experienced instructor, the result is likely only to exacerbate any unwanted and ill-conceived conclusions imaginable by an innovative novice pilot! Toward this end we all MUST recognize that an important aspect of "simulator use" is that merely having the student complete each of the tasks contained in the “syllabus-for-the-day,” even satisfactorily, is no guarantee that the student pilot will have learned what is necessary, will have practiced what is important, or will be able to satisfactorily perform in the real world in a similar set of circumstances.
Therefore, my friend, your comment…
…can only be addressed by referring anyone interested to the on-going UK’s Royal Aeronautical Society’s efforts … 2 of which are described below:
Tuesday 23 September
INTERNATIONAL FLIGHT CREW TRAINING CONFERENCE 2014
The International Pilot Training Consortium: Next Steps?
The Annual International Flight Crew Training Conference is a premier event in the Royal Aeronautical Society’s annual calendar. The 2014 Conference on Tuesday 23, Wednesday 24 and Thursday 25 September at the Society’s Headquarters in London will examine the work undertaken by the International Pilot Training Consortium (IPTC) and seek to determine what further work is required and under what auspices it should be conducted.
Wednesday 12 November
The Future of Flight Training Devices
The objectives of this conference are to examine the recent advances made in the design and use of this class of devices and to identify specific areas of simulation design and data provisioning that requires future enhancement so that further training capabilities and fidelity can be realised.
I am fully aware of (well … maybe not “fully aware, ” but certainly knowledgeable about…) the extent to which airplane cockpit designers go to provide complete and accurate information to the occupants of those cockpits – and, in addition to the amount of information provided, these professionals strive diligently to make that information easily recognizable and immediately useful to those pilots. As I have noted in many of my previous posts in this forum, in my somewhat sordid past, I’ve had the opportunity to see and work with, and for, some of the finest pilot instructors I’ve ever known – and in that process perhaps the most valuable concept to which I was introduced was to find a way to allow the student to use the preferences he/she has come to know and understand to perform any specific task.
The point I had to understand, and to which I had to be willing to commit, was that doing this caused my expenditure of time, effort, and awareness to “skyrocket.” While I readily acknowledge that it is certainly possible that I had to work harder at instructing than did my counterparts … it is equally true that the more I did it, the more I came to recognize that each of the instructors I observed and learned from, also worked very hard to achieve any notable success. The good thing was that when a student’s “light bulb” finally illuminated, I usually felt better than did the student! All of which is to say that ... when you recognize what the student has actually assimilated (not merely regurgitated) the satisfaction far outweighs any thought of "work"
The problem I see today is that instructors often wholly and absolutely depend on the training syllabus (i.e., the lesson plan) and, much to my chagrin and even greater disappointment, the training equipment itself, to “teach” the student what he/she needs to know. What instructors must come to understand is that a fully qualified pilot doesn’t just “happen” at the completion of a training “program” simply by having completed that program. Perhaps the 2 most important things a pilot instructor must know and must know how to address are the following:
1) The structure of a competent training program must include what a pilot must know, what skills a pilot must possess, and what rules a pilot must follow … and all of that has to fit into what that pilot can understand and use – and do so correctly … when things go as planned and when the plan goes askew (i.e., amiss, muddled, twisted, off-center, or just plain wrong); and
2) The flight simulator doesn’t “know” anything – and when such equipment is used without the direct involvement and oversight of a qualified, competent, and relatively experienced instructor, the result is likely only to exacerbate any unwanted and ill-conceived conclusions imaginable by an innovative novice pilot! Toward this end we all MUST recognize that an important aspect of "simulator use" is that merely having the student complete each of the tasks contained in the “syllabus-for-the-day,” even satisfactorily, is no guarantee that the student pilot will have learned what is necessary, will have practiced what is important, or will be able to satisfactorily perform in the real world in a similar set of circumstances.
Therefore, my friend, your comment…
Originally Posted by Bergerie1
I am sure there is a huge amount of research information on the interesting topics that are being discussed in this thread which AirRabbit could direct us to.
Tuesday 23 September
INTERNATIONAL FLIGHT CREW TRAINING CONFERENCE 2014
The International Pilot Training Consortium: Next Steps?
The Annual International Flight Crew Training Conference is a premier event in the Royal Aeronautical Society’s annual calendar. The 2014 Conference on Tuesday 23, Wednesday 24 and Thursday 25 September at the Society’s Headquarters in London will examine the work undertaken by the International Pilot Training Consortium (IPTC) and seek to determine what further work is required and under what auspices it should be conducted.
Wednesday 12 November
The Future of Flight Training Devices
The objectives of this conference are to examine the recent advances made in the design and use of this class of devices and to identify specific areas of simulation design and data provisioning that requires future enhancement so that further training capabilities and fidelity can be realised.
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Asiana
Though a bit far from Asiana accident, i like to see the whole scale of an instrument when i need information from it. with fixed pointer and rolling background my brain takes additional moment to comprehend.
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i like to see the whole scale of an instrument when i need information from it. with fixed pointer and rolling background my brain takes additional moment to comprehend.
The other advantage is an intuitive sense of the direction, and rate of change, of the indication.
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"Human factors" has , is , and will always be a factor in all the future accidents. The interface between man and machine will always be a problem".
Absolutely incorrect. Fully automated robot aircraft, without expensive holes cut out all over the airframe, are just around the corner. The airborne pilot is now basically a computer monitor, not long before taking a seat alongside his ATC counterpart.
Contentious, yes, but highly likely.
Absolutely incorrect. Fully automated robot aircraft, without expensive holes cut out all over the airframe, are just around the corner. The airborne pilot is now basically a computer monitor, not long before taking a seat alongside his ATC counterpart.
Contentious, yes, but highly likely.
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This discussion of displays was touched on in another Tech Log thread, and with your permission, I'll cross-post a snippet:
As far as primary flight instruments go, a bit of Google-bashing drew my attention to a seminal 1949 report for the Journal of Applied Psychology by one Walter F. Grether - probably the best retrospective can be found at this link:
http://repository.asu.edu/attachment...010N_11979.pdf
However, further supporting info on the study can be found with a Google search on "Grether 1949 altimeter".
The gist of the findings was that the traditional three-pointer dial design proved to be by far the most susceptible to misreads, and the optimum dial design used a single pointer with a dual-drum digital counter (which I'm guessing evolved into the combination drum/pointer altimeter that later became nearly ubiquitous prior to the advent of the PFD). The study also noted, however, that the vertical "tape" design (at a concept/experimental-only stage at the time of the report) was very close in terms of speed of reading and not far off in terms of reading accuracy.
It's worth reading through the article linked above, as it gives a very useful precis of how the modern civil PFD evolved, and some very interesting background info on the primary design considerations - the short version being that, as ever, it was a compromise.
http://repository.asu.edu/attachment...010N_11979.pdf
However, further supporting info on the study can be found with a Google search on "Grether 1949 altimeter".
The gist of the findings was that the traditional three-pointer dial design proved to be by far the most susceptible to misreads, and the optimum dial design used a single pointer with a dual-drum digital counter (which I'm guessing evolved into the combination drum/pointer altimeter that later became nearly ubiquitous prior to the advent of the PFD). The study also noted, however, that the vertical "tape" design (at a concept/experimental-only stage at the time of the report) was very close in terms of speed of reading and not far off in terms of reading accuracy.
It's worth reading through the article linked above, as it gives a very useful precis of how the modern civil PFD evolved, and some very interesting background info on the primary design considerations - the short version being that, as ever, it was a compromise.
As an aside, I dug up this image which purports to be a real A330 PFD:
As you can see, at FL400 the most significant three digits are emphasised on the numerical display, and because of this emphasis it should be fairly easy to determine that the numbers are winding down (even more obvious in concert with the "tape" and the V/S pointer).
As you can see, at FL400 the most significant three digits are emphasised on the numerical display, and because of this emphasis it should be fairly easy to determine that the numbers are winding down (even more obvious in concert with the "tape" and the V/S pointer).
FDG135, Bergerie, AR, et al 
For those still not convinced that dials have an advantage over tape displays consider a small simulator experiment involving tape displays and pilots who might not expect …
Night IMC, limiting performance takeoff, without FD / AP (MEL).
Engine failure before V2; then introduce the need to accelerate for an emergency turn.
You may only have one chance to learn.
Tape displays are adequate for many situations, particularly when supported by AT, AP, FD, but without these (or even with them) there can be a range of scenarios where combinations of training standards, levels of experience, and task demand, can erode human capacity so that even if only a little extra focus is required on a tape, it is too much; cf recent accidents, and ASAGA.
DW, beware the assumption “should”; in the conditions shown Mach is more important and can change by relatively large values vs a change in airspeed.
For those still not convinced that dials have an advantage over tape displays consider a small simulator experiment involving tape displays and pilots who might not expect …
Night IMC, limiting performance takeoff, without FD / AP (MEL).
Engine failure before V2; then introduce the need to accelerate for an emergency turn.
You may only have one chance to learn.
Tape displays are adequate for many situations, particularly when supported by AT, AP, FD, but without these (or even with them) there can be a range of scenarios where combinations of training standards, levels of experience, and task demand, can erode human capacity so that even if only a little extra focus is required on a tape, it is too much; cf recent accidents, and ASAGA.
DW, beware the assumption “should”; in the conditions shown Mach is more important and can change by relatively large values vs a change in airspeed.
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Right, but another thing touched upon in the other thread is that the V/S pointer (to the right of the ALT tape) does change angle, so I would suppose that this particular design decision was intended to give a "best of both worlds" approach.
From before the stall, until the moment it hit the Atlantic, the airspeed indications were correct and proper!
You need to look at the graph appendix in the actual report.
From ~24,000 feet on down there were only two very, very short periods where computed airspeed was not NCD. Even prior to that there were periods of NCD interspersed with inaccurate values. NCD on a round dial would have looked similar to what I posted earlier. It was an air data computer problem, not an airspeed indicator problem.
As a matter of interest, if you were to encounter icing induced unreliable airspeed in whatever you fly, what is your benchmark for categorically stating, "airspeed is now reliable again". This is somewhat problematical if you've ever encountered it, round dial or tapes, until you can unequivocally correlate it with pitch attitude and power setting or AOA if so equipped. It's easy to fly thru it, less so to be sure it's over, especially if one induces as many flight path variables as they did.
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No they weren't. They came back correctly from around 02:10:36 to 02:11:43, but after that point the AoA exceeded approximately 30 degrees, which caused the vertical airflow to foul the pitot tubes and render airspeed data useless. This disruption of airflow meant that there was no useful airspeed information from that point until impact at 02:14:28 - a little over two and a half minutes.
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Dozy and OK465,
The traces of "computed airspeed" from the final report show a mixture of spikes (high and low) and valid readings for the final 3 minutes. But that is "computed" airspeed, not necessarily the same thing that you would see if you were trying to display the pitot-static quantity on a big round dial.
The traces of "computed airspeed" from the final report show a mixture of spikes (high and low) and valid readings for the final 3 minutes. But that is "computed" airspeed, not necessarily the same thing that you would see if you were trying to display the pitot-static quantity on a big round dial.
Last edited by FGD135; 14th Aug 2014 at 01:56.
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until you can unequivocally correlate it with pitch attitude and power setting or AOA
....only a non-pilot can make such a comparison
Really ? 22,000 + hrs over 37 years of commercial / airline flying, and not once hitting a sea wall because I let the speed get too low - QED methinks ?
However, I accept that in this accident it really didn't matter whether or not the ASI was digital or analogue, there was a requirement to monitor the airspeed, and the crew would know where to look for that information if they chose to, whether they would have noticed a rate of change more easily with an analogue presentation will never be resolved.
On the Classic 747 there was a block of 20 engine instruments, 5 for each of 4 engines, in the centre instrument panel. With take-off power selected, all 20 'clocks' pointed to 4 o'clock, not be accident but by design. Should one parameter change, it stuck out like sore thumb. I can't comment on how this was dealt with on the 747-400 digital display, i.e. is it so patently obvious when something is wrong ?
I have very little experience of digital 'glass cockpits', but the few I have flown have had 'standby / backup ' instruments that were analogue. Surely, in the event of an emergency requiring scrutiny of a back up instrument, shouldn't this also be digital ? How will an experienced digital pilot react to a stressful situation at low level, in bad weather maybe, and having to cope with a totally unfamiliar analogue instrument as well ? How to achieve digital back ups isn't my problem, but surely it should be the goal ?
I fly two LSA aircraft, one long in the tooth and equipped with a totally analogue display, the other new and 'glass cockpit', but on this aircraft I can, with a press of a couple of buttons ( if I can remember which ! ) change the 'picture' to a digitalised display of 'round' instruments, to increase my comfort zone.
OK, I'm an Old Fart and don't have to change, but I have to fly as passenger - and do wonder sometimes ? Have we really gone in the right direction ?
Really ? 22,000 + hrs over 37 years of commercial / airline flying, and not once hitting a sea wall because I let the speed get too low - QED methinks ?
However, I accept that in this accident it really didn't matter whether or not the ASI was digital or analogue, there was a requirement to monitor the airspeed, and the crew would know where to look for that information if they chose to, whether they would have noticed a rate of change more easily with an analogue presentation will never be resolved.
On the Classic 747 there was a block of 20 engine instruments, 5 for each of 4 engines, in the centre instrument panel. With take-off power selected, all 20 'clocks' pointed to 4 o'clock, not be accident but by design. Should one parameter change, it stuck out like sore thumb. I can't comment on how this was dealt with on the 747-400 digital display, i.e. is it so patently obvious when something is wrong ?
I have very little experience of digital 'glass cockpits', but the few I have flown have had 'standby / backup ' instruments that were analogue. Surely, in the event of an emergency requiring scrutiny of a back up instrument, shouldn't this also be digital ? How will an experienced digital pilot react to a stressful situation at low level, in bad weather maybe, and having to cope with a totally unfamiliar analogue instrument as well ? How to achieve digital back ups isn't my problem, but surely it should be the goal ?
I fly two LSA aircraft, one long in the tooth and equipped with a totally analogue display, the other new and 'glass cockpit', but on this aircraft I can, with a press of a couple of buttons ( if I can remember which ! ) change the 'picture' to a digitalised display of 'round' instruments, to increase my comfort zone.
OK, I'm an Old Fart and don't have to change, but I have to fly as passenger - and do wonder sometimes ? Have we really gone in the right direction ?
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Originally Posted by Chronus
"Human factors" has , is , and will always be a factor in all the future accidents. The interface between man and machine will always be a problem".
Absolutely incorrect. Fully automated robot aircraft, without expensive holes cut out all over the airframe, are just around the corner. The airborne pilot is now basically a computer monitor, not long before taking a seat alongside his ATC counterpart.
Contentious, yes, but highly likely.
Absolutely incorrect. Fully automated robot aircraft, without expensive holes cut out all over the airframe, are just around the corner. The airborne pilot is now basically a computer monitor, not long before taking a seat alongside his ATC counterpart.
Contentious, yes, but highly likely.
To prevent this kind of potential I imagine the brighter minds today could come up with all sorts of potentials – each and every one of which would have to have a “fool-proof” (AND “idiot-proof”) methodology that would ensure such signal failures (over-rides, multiple receipts, fading, etc., etc.) would not – and could not – occur. Yeah, I know … 65 years ago RADAR was a “wet dream,” so maybe there will be a way to ensure the kind of signal sender/receiver individuality that such a system would require … but that, in and of itself, may make the whole idea impractical. Again, even if it may be possible to develop and deploy such a system, it’s not likely that such a system would require only some small addition to the price of an airline ticket! I wouldn't hold my breath waiting for something like this to appear in your local airline operating plan.
Last edited by AirRabbit; 14th Aug 2014 at 22:21.
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A few posts ago (#1034) Dozy posted a link to a study related to cockpit instrumentation. That link is:
http://repository.asu.edu/attachment...010N_11979.pdf
It reports on numerous other studies and experiments involving instrumentation, including tapes. The reports are almost universally damning of the tape displays.
Here are all the relevant passages from that work, including those "favourable" to tape displays. (Bolding is mine).
Dear oh dear. So why do we have tapes today? Because they display the information better? Not at all. As you will read below, it is most likely due to the airlines preference for weight and maintenance savings!
In the following, he is initially referring to two altitude tape presentations that were trialled:
In the following, he is referring to how the bugs on the airspeed tape can be for speeds that are outside the range currently displayed on the tape:
http://repository.asu.edu/attachment...010N_11979.pdf
It reports on numerous other studies and experiments involving instrumentation, including tapes. The reports are almost universally damning of the tape displays.
Here are all the relevant passages from that work, including those "favourable" to tape displays. (Bolding is mine).
Dear oh dear. So why do we have tapes today? Because they display the information better? Not at all. As you will read below, it is most likely due to the airlines preference for weight and maintenance savings!
A single digital number can be quickly and precisely perceived (Hosman & Mulder, 1997), but limitations with single readouts include poorly displaying dynamically changing data (Sanders & McCormick, 1993; Rolfe, 1965), problems with making quick qualitative estimations (or ‘check readings’) (Sanders & McCormick, 1993; Harris, 2004), and not allowing for easy comparison with reference values ...
Both these moving tape concepts tested very well for speed and accuracy, presenting the required resolution and sense of temporal qualitative movement by a employing a moving linear tape and restricting the displayed range. Moving scales with fixed pointers do however have the considerable disadvantage when compared to a fixed scale and moving pointer that can display the whole range, as a quick glance will not yield an approximate picture of system state ...
Ten years after the Grether study, the USAF has a working model of the moving tape display constructed using 16-mm movie film. Testing in a Link simulator found the tape display to be workable, but pointers resulted in a superior flight performance. Further experimentation with expanded scales and more training was recommended (Mengelkoch & Houston, 1958).
In 1959 the Martin Company did extensive simulator testing of vertical tape instruments, with mixed results but predicting with design improvements that they would become valuable assets in the cockpit (Mengelkock, 1959).
NASA conducted simulator experiments with X-15 cockpits equipped with either conventional needle instruments or a vertical-scale fixed-index (ACDS) instrument suite with six tapes and found that, “missions can be carried out as accurately and successfully with the ACDS panel as with the ‘standard’ model” (Lytton, 1967, p. 12).
It was noted that experienced pilots were able to “garner a great deal of information from pointer rates and positions without having to ‘read’ parametric values,” (Lytton, 1967, p. 4) but more precision was expected with longer use of the tape displays due to their considerable gain in display sensitivity (one instrument had 40 inches of tape wound behind the window).
It was noted that experienced pilots were able to “garner a great deal of information from pointer rates and positions without having to ‘read’ parametric values,” (Lytton, 1967, p. 4) but more precision was expected with longer use of the tape displays due to their considerable gain in display sensitivity (one instrument had 40 inches of tape wound behind the window).
A problem with moving tape/fixed pointer displays is possible confusion caused by mixing this format of presentation with fixed tape/moving pointer displays in the same cockpit (known as the principle of the moving part, see Christensen, 1955; Roscoe, 1968; Johnson & Roscoe, 1972). However tape displays have been shown to be still readable when used with a variety of other instrument formats, and offer the practical advantage of a very compact form.
Sanders and McCormick conclude that:
Although fixed scales with moving pointers are generally preferred to
moving scales with fixed pointers, the former do have their limitations,
especially when the range of values is too great to be shown on the face
of a relatively small scale.
Although fixed scales with moving pointers are generally preferred to
moving scales with fixed pointers, the former do have their limitations,
especially when the range of values is too great to be shown on the face
of a relatively small scale.
Electro-mechanical moving tape displays for airspeed and altitude entered service in transport category aircraft in 1964 with the introduction of the United States Air Force C141 aircraft, and were also deployed in the C5 fleet starting in 1969 (Hawkins, 1987). The tape-based “Integrated Flight Instrument System” (IFIS) was used in several U.S. front-line fighters (e.g. the F-105) developed in the 1960’s, as well as in the initial Space Shuttle cockpit (Lande, 1997).
Following the IFIS, small (five-inch rather than eight-inch) tape displays for altimeter and airspeed indicators were evaluated by Tapia, Strock, and Intano (1975) at the USAF Instrument Flight Center.
While the airspeed display was found to be adequate for future use, the altimeter display had some problems with the lack of range presented by the smaller size of tape. An indication of the limitations of tape displays in dynamic flight environments is seen in the midseventies when the USAF moved away from tape displays for heads down primary flight displays but retained their use for Head Up Display (HUD) symbology, seen for example in the F-15 (Lande, 1997). Air Force research presented in 1990 found HUD pointers better in basic flight performance than HUD tapes (Ercoline & Gillingham, 1990), and pointers rather than tapes are recommended by several sources for HUD applications (for an extensive review of HUD issues see Newman, 1995).
A reminder that tape displays are also not optimum when a pointer can cover the required range was seen in testing of several formats for an F-16 vertical velocity indicator (Cone & Hassoun, 1991).
Following the IFIS, small (five-inch rather than eight-inch) tape displays for altimeter and airspeed indicators were evaluated by Tapia, Strock, and Intano (1975) at the USAF Instrument Flight Center.
While the airspeed display was found to be adequate for future use, the altimeter display had some problems with the lack of range presented by the smaller size of tape. An indication of the limitations of tape displays in dynamic flight environments is seen in the midseventies when the USAF moved away from tape displays for heads down primary flight displays but retained their use for Head Up Display (HUD) symbology, seen for example in the F-15 (Lande, 1997). Air Force research presented in 1990 found HUD pointers better in basic flight performance than HUD tapes (Ercoline & Gillingham, 1990), and pointers rather than tapes are recommended by several sources for HUD applications (for an extensive review of HUD issues see Newman, 1995).
A reminder that tape displays are also not optimum when a pointer can cover the required range was seen in testing of several formats for an F-16 vertical velocity indicator (Cone & Hassoun, 1991).
The Airbus A320 introduced moving tapes with all flight
instruments presented on two eight-inch CRTs (Coombs, 1990). The Boeing Company conducted extensive research in the mid 1980’s into vertical tape instruments, finding some concerns:
They lacked relationships that were used extensively by pilots in performing flight tasks. This perception was strengthened by human factors research, which also concluded that, in general, moving scale displays are not as effective as moving pointer displays. The design constraints for the 747-400 PFD and the controversies that surrounded the vertical tape presentation provided a significant challenge to the display design engineers. (Konicke, 1988, p. 1)
Driven by explicit airline demands for the maintenance savings of CRTs over electromechanical pointers and the space requirements of matching the Airbus eight-inch screens, Boeing eventually chose vertical tapes for the 747-400.
Tape displays for airspeed, altitude, and often heading have since become standard in electronic flight displays both civil and military aircraft (Long & Avino, 2001).
instruments presented on two eight-inch CRTs (Coombs, 1990). The Boeing Company conducted extensive research in the mid 1980’s into vertical tape instruments, finding some concerns:
They lacked relationships that were used extensively by pilots in performing flight tasks. This perception was strengthened by human factors research, which also concluded that, in general, moving scale displays are not as effective as moving pointer displays. The design constraints for the 747-400 PFD and the controversies that surrounded the vertical tape presentation provided a significant challenge to the display design engineers. (Konicke, 1988, p. 1)
Driven by explicit airline demands for the maintenance savings of CRTs over electromechanical pointers and the space requirements of matching the Airbus eight-inch screens, Boeing eventually chose vertical tapes for the 747-400.
Tape displays for airspeed, altitude, and often heading have since become standard in electronic flight displays both civil and military aircraft (Long & Avino, 2001).
The analog (airspeed indicator) display maps an abstract
conceptual quantity, speed, onto an expanse of physical space. This
mapping of conceptual structure onto physical space allows important
conceptual operations to be defined in terms of simple perceptual
procedures. Simple internal structure (the meanings of the regions on the
dial face defined by the positions of the speed bugs) in interaction with
simple and specialized external representations perform powerful
computations. (Hutchins, How a cockpit remembers its speeds, 1995, pp.
285-6).
conceptual quantity, speed, onto an expanse of physical space. This
mapping of conceptual structure onto physical space allows important
conceptual operations to be defined in terms of simple perceptual
procedures. Simple internal structure (the meanings of the regions on the
dial face defined by the positions of the speed bugs) in interaction with
simple and specialized external representations perform powerful
computations. (Hutchins, How a cockpit remembers its speeds, 1995, pp.
285-6).
This limitation was noted by Mejdal, McCauley and Beringer (2001):
Today’s designers are less constrained by technology and do not have to present the entire scale or compass or airspeed dial. They now have the tempting option of presenting only the current value of the indicator, which can easily lead them into designing a poorer interface. (Mejdal, McCauley, & Beringer, 2001, p. 45)
Today’s designers are less constrained by technology and do not have to present the entire scale or compass or airspeed dial. They now have the tempting option of presenting only the current value of the indicator, which can easily lead them into designing a poorer interface. (Mejdal, McCauley, & Beringer, 2001, p. 45)
Not all the reference values disappear; the most important reference speeds are presented in an offscale manner (figure 9) when they exceed the normal range, but this is not an elegant solution. Understanding the difference between that speed and current system state now requires the operator to perform mental mathematics, rather than directly seeing the difference.
The problem is that bug values can be close to system values, but not visible to the operator as they are moved off scale. The current partial solution is to present a numerical value offscale (figure 12) but this is limited to one or two values and requires cognitive rather than perceptual processing.
The problem is that bug values can be close to system values, but not visible to the operator as they are moved off scale. The current partial solution is to present a numerical value offscale (figure 12) but this is limited to one or two values and requires cognitive rather than perceptual processing.
Hutchins writes:
As technology changes, there is always a danger of discarding useful properties that were not recognized in the replaced technology. In their current form, the airspeed tapes that have replaced round-dial instruments in the state-of-the-art cockpits defeat some of the perceptual strategies of pilots.
The new instruments offer few perceptually salient cues that pilots can map to their concept of fast/slow in the performance envelope of the airplane. This requires pilots to read the displayed speed as a number and to subject the representation of that speed to further symbolic processing in order to answer the questions that were answered simply by looking at the earlier display. (Hutchins, 2000, p. 69)
As technology changes, there is always a danger of discarding useful properties that were not recognized in the replaced technology. In their current form, the airspeed tapes that have replaced round-dial instruments in the state-of-the-art cockpits defeat some of the perceptual strategies of pilots.
The new instruments offer few perceptually salient cues that pilots can map to their concept of fast/slow in the performance envelope of the airplane. This requires pilots to read the displayed speed as a number and to subject the representation of that speed to further symbolic processing in order to answer the questions that were answered simply by looking at the earlier display. (Hutchins, 2000, p. 69)
Harris, 2004, noted, “the windowed design can be quite poor at providing the pilots with anticipatory information. On the electromechanical counter-counter altimeter, the altitude ‘bugs’ were always visible.” (p. 87). Although new displays have been tested before entering service into aircraft, the aircraft cockpit may not yet be fully mature.
Billings, 1997, reported that there were, “disquieting signs in recent accident investigation reports that in some respects our applications of aircraft automation technology may have gone too far too quickly, without a full understanding of their likely effects on human operators.” (p.34)
Billings, 1997, reported that there were, “disquieting signs in recent accident investigation reports that in some respects our applications of aircraft automation technology may have gone too far too quickly, without a full understanding of their likely effects on human operators.” (p.34)
Glass cockpits allow designers to present huge amounts of data, indeed:
Information management technology has all but erased the problem of
insufficient data in the system. Data, however, is not information. It
becomes information only when it is appropriately transformed and
presented in a way that is meaningful to a person who needs it in a given
context. (Billings, 1997, p. 42)
Information management technology has all but erased the problem of
insufficient data in the system. Data, however, is not information. It
becomes information only when it is appropriately transformed and
presented in a way that is meaningful to a person who needs it in a given
context. (Billings, 1997, p. 42)
Being able to present more bug and reference values graphically on the tape display would fit the principle of proximity compatibility (Wickens & Carswell, 1995; Wickens & Andre, 1990), a concept that is broken by (the common current solution) displaying important values numerically next to a graphic tape.
Proximity compatibility is a movement towards expanding a single perceptual object display rather than forcing the human to cognitively integrate several inputs (Carswell & Wickens, 1987).
Proximity compatibility is a movement towards expanding a single perceptual object display rather than forcing the human to cognitively integrate several inputs (Carswell & Wickens, 1987).
Instrumentation has moved from being initially designed around mechanical practicalities (e.g. the pitot pressure driven round airspeed dial), to more humancentered electro-mechanical presentations (e.g. the tape airspeed indicator), to today’s fully electronic computer graphic presentations (e.g. the A320 PFD with its dynamic bugs and limitation arcs added to the tape display). We may now be overdue for a redesign of these displays to more match human perceptual and cognitive abilities.
Writing in Science, Hirschfeld (1985) noted that, “more effort in
display psychophysics will be needed to match instrument output to brain input.
Writing in Science, Hirschfeld (1985) noted that, “more effort in
display psychophysics will be needed to match instrument output to brain input.
Last edited by FGD135; 14th Aug 2014 at 05:14.