Paravisual Display (PVD) 747-400

[wiggy]

On the T7/744 you need to have the freq and LOC course hard tuned on the NAV RAD page.

Is it simply a system that gives better peripheral and faster/quicker recognition needed because of the higher cockpits of the wide bodies resulting in greater slant ranges for seeing the runway lighting,

I guess the logic is something like that. the display sits just at the bottom of your peripheral vision and as Pontius says it's very intuitive to use

All that said our latest T7s are being delivered without them, story goes they (well the one's we use) are expensive to maintain and in reality are rarely used in anger.

[rudderrudderrat]

Hi Pontius,

It's not bright enough to roll right to intercept the centreline. It's not a flight director that is taking into account turn rates.....

I beg to differ.
During line up at taxi speed, the TriStar PVD would be steady with an intercept heading towards the centre line and then show a turn command to align with the centre line.
It was certainly more sophisticated than a simple localiser deviation display, and it considered:
airplane yaw rate
cross body acceleration
localiser deviation
localiser deviation rate.

[Winnerhofer]

PVD

No self-respecting airline can be without this option.
It has unfortunately disappeared on the B748,B777x and B788.
In Airbus parlance it's called PVI but only one indicator on LH-side and this too is no longer on the option list of A388, A350 and A320 Neo.

[Aluminium shuffler]

Thanks, Wiggy.

Would I be right in y understanding that they rotate fast the greater the displacement from the centre-line?

It seems a shame to remove or omit kit that the pilots have a clear and unanimous liking of, but that's what happens when engineers and accountants have absolute dictat over cockpit design... Engineers can come up with wonderful solutions to problems, but only pilots can know what works and what doesn't for us. I get the impression that modern test pilots are told merely to prove the design flies, and not allowed to feed back recommendations of what would make it better for line pilots and crew.

[By George]

My old company deactivated the PVD on the 744 for the simple reason they were never needed. Tragically the one time they might have saved the day in Taiwan, the crew failed to recognize the off-set indication.
We were CAT3b on the 744 and the R/W centre lights were more than adequate. The recency requirements in the Sim and the fact it was never really needed, killed it off. Maybe Boeing agrees. I found it very useful for an engine failure in low vis but that is all. Sometimes the men in white coats can have too many gadgets. (my new car suffers from Geek Overload and is driving me nuts).

[EEngr]

wiggy:

are expensive to maintain

Quick survey. Are PVDs (where installed) still largely implemented as electro-mechanical displays? Or have they gone to something like a one line graphic LCD?

[By George]

Engr, On the 744 they were electro-mechanical. Quite noisy going on test with a 'click clack' sound. The 'blind' was yellow and black stripes.

[Winnerhofer]

PVD

Scroll down to pic #2 :
744 Gallery 04

[EEngr]

So, if their elimination is an issue of maintenance expense and this is still a valued instrument, it surprises me that someone hasn't come out with a 'digital' barberpole display. Quite simple to to with a one line graphical LCD properly backlit. No moving parts and no noise.

Unless you like the noise. We could easily emulate that.

[Dan Winterland]

My old company deactivated the PVD on the 744 for the simple reason they were never needed. Tragically the one time they might have saved the day in Taiwan, the crew failed to recognize the off-set indication.

One of them did - the F/O sitting on the jump seat. He mentioned it to the Captain, but was dismissed.

I used to fly 744s with PVDs fitted, but never used them in anger. Most Capatains chose not to use them as many pilots don't find the dispaly intuitive.

The PVI is an option on FBW Airbus and (I gather) it is an LCD display. But very few operators have taken up the option.

[henry_crun]

History

I was at Smiths, working in the design labs, CH3, and can recall seeing our barbers pole type Para-Visual Director which was invented by Mr Majendie, I think he was one of our test pilots.

Photo as Fig 1 in here:
http://ntrs.nasa.gov/archive/nasa/ca...1969005146.pdf

Correction - Mr Majendie was a de Havilland Test Pilot, which would figure because we were doing the DH Trident Autoland. Saw him once when he visited Test Equipment lab.