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Old 30th Jul 2014, 03:21
  #937 (permalink)  
FGD135
 
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Bring back the big round airspeed indicator

You are welcome to have your own opinions but multiple studies (including NASA's) on this subject do not support your conjecture.
What studies, olasek? Can you give some pointers or links to at least one, please. There is just no way that a speed tape, which requires reading digits from a 1" x 1" patch of panel, can be better than the big dial with pointer - which requires only a glance for assessment of angular position, with no reading and processing of digits required.


Would be very interested to know about any studies that have been done. I suspect that no proper studies have actually been done. I did a search myself recently but couldn't find anything. I am in the process of writing to the NTSB to question them about the human factors of tape vs pointer. I will be asking them about studies.


See the pointer is in the big, bad, red & black bit and you know instantly that's not good.
That is AFTER THE PLANE HAS STALLED, Pontius, you clown. The key issue in all of these stalls is the airspeed decay (prior to the stall) that went undetected by the pilots.


Look at the pointer on the big round dial of yesterday and see that it's pointing at some arbitrary point. It might be bad, it might not be so bad. But you don't know until you compare it to the stall speed for the weight of the aircraft at the time.
Are you even a pilot, Pontius? Let me tell you how the pilot brain works when making an approach using the big round dial of yesteryear. Given that you have been trained on the aircraft, and done several approaches, you are familiar with where the airspeed pointer should roughly point, for each stage of the approach.


At the initial fix, for example, you know roughly where it should be. A quick glance will confirm whether it is. No need to read any digits. After the final fix, ditto. If you were seconds from stalling, the angular position would be very different and you would pick this, almost instantly - without having to read any digits.


One study I would really like to see is whether there is a correlation between stall-related accidents and the introduction of the glass cockpit speed tape. Over the last 5 years, 4 of the highest profile accidents have all involved a stall.


Many of the modern instruments have been developed so that we can instantly ascertain the situation and the speed tape is certainly one of them.
That is laughable, Pontius. Airspeed was made into a tape for the same reason that altitude was - because there was not enough room on the little screen to display them any other way.


IF the Asiana crew had looked at their speed tape they would have known the situation.
I suspect you are agreeing with me when I said that their speed tape had, in effect, become invisible. This is the whole problem with the speed tape - it requires way too much brain power to use.


When humans are in high work load and high stress situations they "task shed" - the more difficult the task, the sooner it gets shed. Reading a speed tape is easy in a low stress situation, but for Asiana 214, preoccupied with AFCS perhaps, Colgan 3407, Turkish 1951 and Air France 447, it is obvious that the tape indication was not utilised.


The plane was unable to tell the pilots about its airspeed, in other words. With the big round dial of yesteryear, the indications would have been so strong, the dial would have been practically yelling at them. With the tape, you have to ask it for what it has. But listen carefully for its reply, for it is only a whisper.

Last edited by FGD135; 30th Jul 2014 at 04:13.
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