747-400 "Airspeed Tape Reversed"
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From: Australia
747-400 "Airspeed Tape Reversed"
The 744 has a pin-programmable EFIS option: "Airspeed tape reversed".
Are there any airlines out there using this option?... If so, does anyone have a photo of this configuration.
Thanks!
Rgds
NSEU
Are there any airlines out there using this option?... If so, does anyone have a photo of this configuration.
Thanks!
Rgds
NSEU
Joined: Dec 2002
Posts: 2,775
Likes: 353
From: UK
The Avro RJ series has an option for an ‘inverted’ airspeed tape, but it was not offered to operators. The certification advice was that all types of aircraft in a given fleet (and subsidiary fleets) would have to have the same orientation of display. Thus the Boeing / Airbus arrangement predominates.
There are peculiarities with the standard arrangement, especially when flying without autothrottle or flight director; N.B. MEL items. Much more attention is required to relate speed with pitch change, e.g. engine failure after takeoff and no FD – try it in the sim.
There are peculiarities with the standard arrangement, especially when flying without autothrottle or flight director; N.B. MEL items. Much more attention is required to relate speed with pitch change, e.g. engine failure after takeoff and no FD – try it in the sim.
Joined: Aug 1998
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From: Ex-pat Aussie in the UK
Have to say - I like the idea. If you bug an altitude, then "pitching up/down towards the bug" is natural and intuitive. If you bug a speed, on a standard tape, it operates in the reverse sense - flying faster than bugged, you have to pitch up (away) from the bug to regain the correct speed. Reversing the sense of the speed tape corrects this.
Joined: Dec 2002
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From: UK
Checkboard, you describe a central aspect in the debate about the speed tape orientation.
Speed tape displays were first made available in large commercial aircraft which had autothrust and flight directors. The workload / ergonomic studies conclude that the ‘inverted’ format was optimum. This conclusion also considered what is normally taught in basic training on aircraft without these facilities, and that pilots of the larger, non EFIS aircraft had to transition to autothurst / FD anyway, thus changing their perspective of the pitch / speed relationship. A subsidiary argument involved heavy aircraft characteristics, which in general moved the approach path flight control towards the ‘back side' of the drag curve, and where pitch change does not dominate speed change (light aircraft) vs the larger effects of thrust change on speed in commercial aircraft.
Gulfstream, had a choice, but being the first ‘GA’ installation elected for a high speed up orientation, perhaps concluding that their pilots experience / training would be a closer match to the techniques taught in basic training.
During the period where the large CRT / EFIS displays were becoming available, there were extensive studies of dial airspeed instruments in many forms, but none could provide equivalent characteristics to those of an electromechanical instrument (excepting the BAe/Smiths AFD/BAC1-11 experiment).
With even larger displays – two of them, the 737 has moved back to a well tried and tested dial solution. Similar issues apply to the tape altimeter.
Speed tape displays were first made available in large commercial aircraft which had autothrust and flight directors. The workload / ergonomic studies conclude that the ‘inverted’ format was optimum. This conclusion also considered what is normally taught in basic training on aircraft without these facilities, and that pilots of the larger, non EFIS aircraft had to transition to autothurst / FD anyway, thus changing their perspective of the pitch / speed relationship. A subsidiary argument involved heavy aircraft characteristics, which in general moved the approach path flight control towards the ‘back side' of the drag curve, and where pitch change does not dominate speed change (light aircraft) vs the larger effects of thrust change on speed in commercial aircraft.
Gulfstream, had a choice, but being the first ‘GA’ installation elected for a high speed up orientation, perhaps concluding that their pilots experience / training would be a closer match to the techniques taught in basic training.
During the period where the large CRT / EFIS displays were becoming available, there were extensive studies of dial airspeed instruments in many forms, but none could provide equivalent characteristics to those of an electromechanical instrument (excepting the BAe/Smiths AFD/BAC1-11 experiment).
With even larger displays – two of them, the 737 has moved back to a well tried and tested dial solution. Similar issues apply to the tape altimeter.
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From: various places .....
As SP indicates, it goes back to the early days of the electronic marvels - A320 and the like - the flight test fraternity spent some considerable time and effort over which way what should go to provide the most useful presentation for line crews.
