Assuming an MB Mk 4 was fitted to the P1B as with production aircraft
The seat should have functioned as follows:
- The pilot pulls the face screen seat firing handle
- Canopy jettison initiated
- Ejection gun fires, seat moves up guide rails and the secondary cartridges fire
- Emergency oxygen tripped
- Aircrew services disconnect
- Leg restraints operate
- As seat rises, static line initiates time-delay which fires drogue gun after 0.5 seconds
- As seat rises, static line initiates time-release unit 22 in. dia then 5 ft dia drogues stabilise and slow seat
Below 10000ft, (low speed)
- 1.5 second (3 seconds on earlier Mk 4 seats, 1.25 sec on later Mk 4 seats) after initiation of time-release unit
- The plunger releases scissor shackle to transfer pull of drogue to lifting lines of parachute, releasing it from seat
- Release face blind
- Harness and leg lines released from seat
- Drogues deploy main parachute, pilot separates from seat
- Normal descent
- Manual separation system available if necessary. Operation of manual separation handle fires a cartridge that operates a guillotine, severing the parachute attachment line, linkages function releasing parachute harness, negative-g strap, PEC and leg restraint cords.
- Freeing parachute from seat. Pilot can then use rip cord to operate parachute.
First successful ejection using a Mk4 was from a G.91 in March 57 - XG332 ff 29 May 1959 so I assume it was an early model seat