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Ray Double
30th Apr 2002, 14:42
Sorry, my last big airplane job was 747-200 and now I'm flying corp. LearJets. So could someone explain or point me to a web site, that will give me the basics of a PVD, such how it works, displayed to the flight crew, limitations, ect.

Thanks, Ray

G.Khan
1st May 2002, 09:59
Ray - this will be simple, since that is me at my best!:D

I will describe this from the captains side, just reverse the lefts and rights for the F/O's side, B747-400.

The PVD display is an oblong window in the coaming in front of each pilot, it is about 4 inches long and a half inch wide.

When switched to 'On' from the pilots instrument lights control panel, ( further left and down a bit), the display shows a black and white 'barbers pole', diagonal bands, alternating black and white, sloping inwards.

The PVD requires a localiser signal to operate. When lined up on the centre of the R/W the display should be still.

As one accelerates down the runway, if one remains in the centre, the display will remain still.

If one veers to the left the pole will rotate showing that one should correct to the right, the direction that the pole appears to be moving, exactly the opposite of one veers to the right of centre line.

SQ6, on 05R, was probably outside the protected area for the localiser signal but the instrument, if it was receiving the signal, MAY have shown that the aircraft should have been correcting to the LEFT, continuously. It is a guide only, if you Believe you are on the correct R/W then it would be human nature to assume that the instrument was playing up, they do sometimes.

The system has various limitations and conditions but that is it, very basically!:)