|Quoting TristarSteve (Reply 1):
It was introduced on the Trident by BEA in 1964 and has been fitted to many BEA and BA aircraft since. It was on the BA Tristar and B767 and B757 and was a requirement for Cat3B operation.
It was an option on the 744 and it would cut the takeoff mins by 50% (IIRC). It was driven by the takeoff runway ILS and the trick was to keep the stripes from moving.
The PVD system consists of one PVD computer and two PVD indicators. The
PVD computer receives guidance commands from three FCCs. The FCC source
is selected with the FD/PVD source selector for the respective display.
Using the runway localizer tuned on the Navigation Radio page, the PVD provides
guidance to runway centerline during ground operations.
In practice, it was a terrible system and about 18 months ago SQ
deactivated the system on the 744. It had no bearing on CATIIIB/C operations. It was merely for takeoff.
[Edited 2008-01-28 04:23:20]