The American F-35 Joint Project Office says ejection seat and helmet modifications will stop emergency ejections from breaking petite pilots' necks.

Pilots who weigh less than 62kg (9¾ stone, 136lb) are currently banned from flying the state-of-the-art F-35 fighter jet because an emergency ejection using the currently fitted Martin-Baker US16E seat could cause potentially fatal neck and spine injuries.

F-35 pilots wear a heavier helmet than pilots of other types of craft – it contains more targeting electronics than previous jets – which weighs about 2.25kg, or 5lbs.

US F-35 Joint Project Office (JPO) director Todd Mellon told US website Defense News: “We're three to four weeks away from having all of the data done so that we can finalize the technical assessment, put that into a risk assessment, and then ultimately make a recommendation.”

Lieutenant General Chris Bogdan, the Americans' F-35 Program Executive Officer, told Martin-Baker in July: “We believe the current Martin-Baker US-16E ejection seat with proposed fixes will meet all F-35 requirements.”

Martin-Baker is keen to keep the F-35 ejection seat contract. As problems caused by the current seat and helmet combination have rumbled on over the past year, the US has threatened to award the contract for F-35 “bang seats” to rival manufacturer United Technologies, though informed sources believe this is an empty threat just to keep Martin-Baker on its toes.

Three key modifications are taking place, according to Defense News. A weight-activated switch in the seat will delay parachute deployment if a smaller pilot is sat in the seat, letting it slow down slightly and thus putting less force on the pilot; a head support panel has been fitted to stop the pilot's neck from “over-flexing backwards”; and helmet manufacturers Rockwell Collins are trying to cut down the helmet's weight.

Military.com affiliate Defense Tech reported in August that, if successful, the modifications would be incorporated into new-build F-35As by 2017 and retrofitted to all existing F-35A aircraft.

A Ministry of Defence spokesman told The Register: “There are no UK F-35 pilots affected by this issue and we do not anticipate any impact on national flying operations while this seat development issue is resolved. The safety of our personnel remains of paramount importance.”

It's anyone's guess as to whether the RAF and Royal Navy's F-35Bs will be equipped with the modified seats and helmets – though it would be very strange if they weren't. The UK is planning full inter-operation with the US Marine Corps' F-35Bs and so keeping two sets of spares aboard HMS Queen Elizabeth would be a needless duplication.

British fast jet pilots flying the Hawk two-seat trainer, used in advanced fast jet training, must weigh a minimum of 8.9 stone (56.5kg), which suggests quite a few serving British aircrew may be ineligible to fly the F-35 once the aircraft gets into squadron service in seven years' time. ®

* In case you hadn't guessed, that's the aircraft ejection seat