Mk5 Ejection Seat

An evolution of the Mk4, manufactured to suit the specific requirements of the United States Navy.


An evolution of the Mk4, manufactured to suit the specific requirements of the United States Navy.

Introduced into service in 1957

1,649 aircrew lives saved using a Mk5 ejection seat

To suit the special requirements of the United States Navy, the Mk5 seat was introduced in 1957 and its production paralleled to that of the Mk4. In general, the Mk5 seats conformed to the same basic pattern of the Mk4 and included the standard 80 feet per second gun, 1¼ second time delay with g switch and barostatic control, duplex drogue system plus all the other features necessary for their use at all speeds and heights. To meet specific American crash requirements, however, the seat structure and harness were strengthened to withstand deceleration loads of 40g, instead of the 25g British specification, resulting in a slight increase in weight.

In addition, the seats were provided with special canopy breaker peaks on the headbox to provide for the eventuality of having to eject through the canopy, standard practice on the A.5 seat installed in the Grumman 9F-8T Cougar. On the majority of the other Mk5 seats, the American system of jettisoning the canopy was linked up with the face blind firing handle. The low-level capabilities of the Mk5 seat were successfully demonstrated in August 1957, when Flying Officer Sidney Hughes ejected from a Grumman Cougar at the U.S. Naval Air Test Centre, Patuxent River, before a group of high-ranking U.S. Navy Officers. Subsequently, the decision was made to standardise the Martin-Baker Mk5 seats for all United States Navy jet fighters and trainers, and many fuselages were sent to the Company’s factory at Denham for trial installations.

North American Sabre and Republic Thunderflash aircraft of the Norwegian Air Force were the first of many N.A.T.O. aircraft to be flown into Chalgrove Airfield where the installation of Martin-Baker Mk5 seats was made, replacing the original American ejection seats fitted in these aircraft, because the Norwegian Air Force preferred Martin-Baker seats. Altogether the Mk5 seat has been fitted to nearly twenty types of American aircraft, including such advanced aircraft as the McDonnell Phantom, L.T.V. Crusader, and Grumman Intruder.

Aircraft fitted: Hawker, Mohawk, CF-105, Sabre, Thunderflash, T-33, F3H Demon, FJ-4 Fury, F4D Skyray, F-4, F-8 Crusader , Cougar Trainer , A6 Intruder
Operating Ceiling50,000+ ft (15,250m)
Minimum height/speedZero/90 KIAS
Crew boarding mass range70.4 to 101.7kg
Crew size range5th to 95th percentile
Maximum Speed for ejection600+ KIAS
Parachute type Irvin I 24
Parachute deploymentDrogue assisted
Drogue parachute typeDuplex drogues 22in. and 5ft
Drogue deploymentDrogue gun. Cartridge generated gas. Initiated by 0.5 sec clockwork time-delay, tripped during ejection sequence
Harness typeCombined
Ejection seat operation typeEjection gun
Ejection gun80 ft/sec One primary cartridge, two secondary cartridges, 72 in. stroke
Ejection initiation Face screen or seat pan firing
Barostatic time-release unitYes, tripped during ejection sequence, g-restrictor, time-release unit for man/seat
Manual override handleYes
Seat adjustmentUp/down, manual operation
Arm restraintsNo
Leg restraintsYes, two garters
Oxygen supplyBottled oxygen
Personal survival packYes with liferaft
Aircrew servicesPersonal equipment connector (PEC) provides connections for, main oxygen, emergency oxygen, air ventilated suit, anti-g suit and mic/tel
Canopy jettisonYes, aircraft variant dependent

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