Track - PVD = Para Visual Display.
It consisted of two 'barber's pole' type indicators mounted horizontally on the glare shield. They were activated from the Localiser and used as steering guidance for low vis take-offs and as reversionary steering aids in the event of A/P disconnects on the landing roll. The direction of rotation of the 'pole' indicated the turn required to regain the centre-line.
BTW - also fitted as standard to BA's 744s.