Table 5-1.-Squib-Fire Event Times
SQUIB-FIRE EVENT TIMES
IN MODES 1 to 5
Altitude (ft)
0—8K
8K—18K
18K+
KEAS
0—350 350—500 500—600 ALL
ALL
MODE
1
2
3
4
5
1
2
3
4
5
6
7
8
Gas pressure from seat initiator cartridges,
delay cartridge or command sequencing
system initiates catapult and thermal batteries
Start switches close after 39 inches of seat
travel
Sequencer supplies dual pulse to fire drogue
deployment catapult
Sequencer supplies dual pulse to fire drogue
bridle release cartridge and release drogue
bridle
Sequencer supplies dual pulse to fire parachute
deployment rocket
Sequencer supplies dual pulse to fire drogue
bridle release cartridge and release drogue
bridle
Sequencer supplies dual pulse to fire barostatic
release unit cartridge and release harness locks
Sequencer supplies dual pulse to fire barostatic
release unit cartridge (backup)
0.00
0.00
0.00
0.00
0.00
0.18
0.18
0.18
0.18
0.18
0.22
0.22
0.22
0.22
0.22
Environmental sensing
time window 0.245 — 0.305 seconds
0.32
—
—
—
4.80 +t
(See Note 3)
0.45
1.10
1,30
2.90
4.87 +t
—
1.25
1.45
3.05
—
0.65
1.30
1.50
3.10
5.07 +t
0.66
1.31
1.51
3.11
5.08 +t
All times are references to ejection seat initiation. The start switches operated approximately 0.18 seconds
after initiation. N. B: This is a nominal time. The actual time will vary between 0.13 and 0.19 seconds.
In Mode 5 operation, altitude sensing is to recommence at 4.80 seconds, continuing until fall-through-
condition (below 18,000 ft) is detected.
t = time interval between 4.80 seconds and fall-through-condition.
Mode 1 is designed for low-speed/low-altitude
deploying drogue and bridle assembly moves
ejection conditions. The aim is to deploy the main
rapidly clear of the seat in readiness for the
parachute as soon as practicable after the seat has
immediate main parachute deployment.
separated from the aircraft. A drogue decelera-
Modes 2, 3, and 4 cater for high-speed
tion phase is not required so the bridle releases
ejections at low and medium altitudes. These
are operated very quickly, thus ensuring that the
ejection conditions require a delay before the
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