Para Visual Display on the 744 (PVD).
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Para Visual Display on the 744 (PVD).
Hi Guys,
Does someone can give me some info about this system ?
Saw it de-activated in a 744 from a well-known very safe airline.
Any pic please ?
Merci.
Does someone can give me some info about this system ?
Saw it de-activated in a 744 from a well-known very safe airline.
Any pic please ?
Merci.
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Briefly, without referring to notes!
1. Tune in the ILS for the departure runway (freq and qdm)
2. Both Capt and FO select PVD on (switch to left/right - for capt/fo) on upperside of coaming
3. Adjust brightness as required
4. When within x (80deg?) of centreline, it displays as a barbers pole
5. In general, during the t/off roll, it will indicate which way to steer according to streaming barbers pole - it is very intuitive.
6. After t/off the displays blanks/shutters
1. Tune in the ILS for the departure runway (freq and qdm)
2. Both Capt and FO select PVD on (switch to left/right - for capt/fo) on upperside of coaming
3. Adjust brightness as required
4. When within x (80deg?) of centreline, it displays as a barbers pole
5. In general, during the t/off roll, it will indicate which way to steer according to streaming barbers pole - it is very intuitive.
6. After t/off the displays blanks/shutters
Smiths PVD
The PVD was developed by Smiths Industries in the UK around 1961.
The original intention was to have one vertically and one horizontally mounted barbers pole in the pilot’s peripheral vision to provide guidance during approach and landing. This configuration was not very effective, I'm not sure if any aircraft actually used it in service.
It was used on Trident aircraft, only utilising the horizontal pole mounted in the glareshield for guidance on the runway, I seem to recall that it was driven by its own separate computer; so most likely a CAA requirement for Cat 3 landings at that time.
I have not been able to locate any pictures.
QA1
The original intention was to have one vertically and one horizontally mounted barbers pole in the pilot’s peripheral vision to provide guidance during approach and landing. This configuration was not very effective, I'm not sure if any aircraft actually used it in service.
It was used on Trident aircraft, only utilising the horizontal pole mounted in the glareshield for guidance on the runway, I seem to recall that it was driven by its own separate computer; so most likely a CAA requirement for Cat 3 landings at that time.
I have not been able to locate any pictures.
QA1
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http://www.asc.gov.tw/downfile/SQ006_ENG.pdf
Go to page 159 of this report. (It's page 182 on the Adobe reader.)
You will get everything you need to know about the PVD.
Go to page 159 of this report. (It's page 182 on the Adobe reader.)
You will get everything you need to know about the PVD.
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No pictures but the system works as follows,
The signal required is the Localiser which is fed to the PVDs. It is used primarilly for roll out control of the aircraft. Any deviation from the centre line is fed to the PVD which makes the barbers pole rotate in such a way that it makes you feel like the aircraft is moving off the centre line. When the deviation is corrected the barbers pole once again stops moving.
A good way of experiencing a similar feeling is to sit on the flight deck on an aircraft outside a hangar and the hangar doors are being opened. Concentrate on the flight deck instruments and the movement of the hangar doors in your parapherial vison will make the aircraft seem like its moving.
The signal required is the Localiser which is fed to the PVDs. It is used primarilly for roll out control of the aircraft. Any deviation from the centre line is fed to the PVD which makes the barbers pole rotate in such a way that it makes you feel like the aircraft is moving off the centre line. When the deviation is corrected the barbers pole once again stops moving.
A good way of experiencing a similar feeling is to sit on the flight deck on an aircraft outside a hangar and the hangar doors are being opened. Concentrate on the flight deck instruments and the movement of the hangar doors in your parapherial vison will make the aircraft seem like its moving.
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Why it has been de-activated if it was so reliable ? (useless ?).
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All our 744's have a PVD except perhaps, two or three aircraft we purchased second-hand from other airlines (these airlines had already deactivated them or never had them fitted).
They are fitted to some 747-400ER's, so they are obviously still in production
Whilst the primary reference is the localiser signal, the PVD's need the Inertial Reference System to compute lateral (sideways) acceleration.
I don't know how intuitive they are, but you steer the aircraft in the direction the display appears to be moving towards.
Rgds.
NSEU
They are fitted to some 747-400ER's, so they are obviously still in production
Whilst the primary reference is the localiser signal, the PVD's need the Inertial Reference System to compute lateral (sideways) acceleration.
I don't know how intuitive they are, but you steer the aircraft in the direction the display appears to be moving towards.
Rgds.
NSEU
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The original intention was to have one vertically and one horizontally mounted barbers pole in the pilot’s peripheral vision to provide guidance during approach and landing. This configuration was not very effective, I'm not sure if any aircraft actually used it in service.
This aircraft was FAA approved, at the time, for CATIII hand flown approaches.
PVD...very effective, if used properly.
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Gents , thank you for your answers and explanations.
The a/c , I have worked on is an ex-SQ (ex-SPB) , thats the reason why Mr Leewan knows about it .
It was the first time that I saw this system , anyway I worked only on the 744 from AF , AC , TG , JL , NH , KE and BR and none of them get it (as far as I can remember...).
Happy to see that even after 20 years experience , I am still discovering new things (from the 60s) ...(who is laughing ?).
Merci.
The a/c , I have worked on is an ex-SQ (ex-SPB) , thats the reason why Mr Leewan knows about it .
It was the first time that I saw this system , anyway I worked only on the 744 from AF , AC , TG , JL , NH , KE and BR and none of them get it (as far as I can remember...).
Happy to see that even after 20 years experience , I am still discovering new things (from the 60s) ...(who is laughing ?).
Merci.
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latent failures and indications
Greetings
The posted link for the file .pdf would not open. Can someone post a better link?
I had a question for anyone with experience with PVD if there was any indication if there was a latent failure in the guidance or if the system was invalid?
Off Flag? Color change? etc.,?
How would the pilot "know" guidance was valid?
Thanks
Nightdog83
The posted link for the file .pdf would not open. Can someone post a better link?
I had a question for anyone with experience with PVD if there was any indication if there was a latent failure in the guidance or if the system was invalid?
Off Flag? Color change? etc.,?
How would the pilot "know" guidance was valid?
Thanks
Nightdog83
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unshuttered PVD
OK, From reading the document, it looks like when it is functioning as intended, the PVD is "unshuttered"
In a more modern glass cockpit, I would make the analogy that the indication would be displayed for view when valid and removed from view when not valid. Kind of like how some Flight Directors are biased out of view when invalid.
For any on the forum who have experience with the PVD, is this a reasonable analogy?
Thanks
Nightdog83
In a more modern glass cockpit, I would make the analogy that the indication would be displayed for view when valid and removed from view when not valid. Kind of like how some Flight Directors are biased out of view when invalid.
For any on the forum who have experience with the PVD, is this a reasonable analogy?
Thanks
Nightdog83
