Key safety measures have still not been introduced on some military aircraft, two years after a Hercules crash killed 10 UK servicemen, the BBC has learned.
Only seven of the Royal Air Force's 48 Hercules aircraft have been fitted with special foam to prevent explosions, the BBC has learned.
Lack of explosive suppressant foam (ESF) has been blamed for the death of 10 servicemen in a Hercules air crash two years ago.
One former Squadron Commander described the situation as "criminally insane".
One former Squadron Commander described the situation as "criminally insane".
An inquiry said the lack of a fuel tank safety system may have contributed to the 2005 crash, the UK's single largest loss of life in the Iraq conflict.
The 2005 crash was the UK's single largest loss of life in the present conflict in Iraq.
But two years on, only seven out of the military's 48 Hercules aircraft have been given the protection they need.
Explosive vapour
Explosive vapour
It is thought the 2005 crash occurred after ground fire caused vapour formed inside a fuel tank in the Hercules's wings to explode.
It is thought the crash occurred after vapour inside a fuel tank in the Hercules's wings exploded after being hit by hostile fire from the ground.
Relatives of the lost crew have been calling for explosive suppressant foam (ESF) - used in US aircraft since the Vietnam War - to be fitted to the entire Hercules fleet so the vapour cannot form.
An inquest on Wednesday into the crash heard submissions that the aircraft's fuel tanks were not fitted with ESF, which stops the vapour forming.
Relatives of the lost crew have been calling for the foam - used in US aircraft since the Vietnam War - to be fitted to the entire Hercules fleet.
Defence correspondent Paul Wood said the aircraft were being used so intensively in Iraq and Afghanistan it was difficult to take them away from the conflict.
Defence correspondent Paul Wood said the aircraft were being used so intensively in Iraq and Afghanistan it was difficult to take them away from the conflict.
I believe there's a very real chance that next time we could lose fifty or sixty people on a Hercules Nigel GilbertFormer Hercules pilot
I believe there's a very real chance that next time we could lose 50 or 60 people on a Hercules Nigel GilbertFormer Hercules pilot
The MoD has said the deaths would not definitely have been prevented had explosive suppressant technology been fitted, but announced in April 2006 it had decided to fit it to some Hercules aircraft.
The Ministry of Defence has said the deaths would not definitely have been prevented had explosive suppressant technology been fitted, but announced in April 2006 it had decided to fit it to some Hercules aircraft.
An MoD spokesman said the programme to fit ESF would be completed by the end of the year.
He added: "The Hercules C130K has been the work horse of the RAF transport fleet since it entered service in the 1960s.
"It's been maintained to the highest standards of the RAF and has an excellent safety record. Lessons are being learned from operations and safety is a primary concern."
Last October, relatives of lost crew handed a petition bearing 2,858 names demanding the measures be installed on the Hercules fleet, which is based at Lyneham, Wiltshire.
Last October, relatives of lost crew handed a petition bearing 2,858 names demanding the measures be installed on the Hercules fleet, which is based at Lyneham, Wiltshire.
Security
Security
Sarah Chapman, whose brother Sgt Robert O'Connor was killed in the crash, said that she believes more deaths are inevitable.
Sarah Chapman, whose brother Sgt Robert O'Connor was killed in the crash, said that she believes more deaths are inevitable.
She added: "I know I will one day be writing to a family member about the loss of their loved one following a death on the Hercules aircraft."
She added: "I know I will one day be writing to a family member about the loss of their loved one following a death on the Hercules aircraft."
Nigel Gilbert, a former Hercules pilot who flew with special forces in Afghanistan, said the MoD had done "too little, too late".
Nigel Gilbert, a former Hercules pilot who flew with special forces in Afghanistan, said the MoD had done "too little, too late".
He went on: "I believe there's a very real chance that next time we could lose fifty or sixty people on a Hercules."
He went on: "I believe there's a very real chance that next time we could lose fifty or sixty people on a Hercules."
In November, the government said only two Hercules planes had been fitted with ESF.
Shadow Defence Secretary Dr Liam Fox said British forces will feel let down by the news.
But in a later answer to a parliamentary question armed forces minister Adam Ingram said fuel leaks were reported on two Hercules C-130 aircraft after being fitted with the foam protection to their fuel tanks.
Liberal Democrat defence spokesman Nick Harvey said: "This is a disaster waiting to happen."
Both were returned to the contractor for repair and subsequently returned to the front line, he said.
'Important capability'
Mr Ingram told the House of Commons in December that "the majority" of the RAF's C-130 Hercules fleet would have ESF by the end of 2007.
But he said he could not reveal the precise number for security reasons.
Air Vice Marshall Andy Pulford said the RAF was doing all it could to minimise risk to aircraft crews and passengers.
He added: "I'm content we are working as rapidly as we can to fit what we see as now a very important capability to our aircraft."
The Lyneham crew members who died were Flt Lt David Stead, 35, Flt Lt Andrew Smith, 25, Flt Lt Paul Pardoel, 35, Master Engineer Gary Nicholson, 42, Chief Technician Richard Brown, 40, Flt Sgt Mark Gibson, 34, Sgt Robert O'Connor, 38, and Cpl David Williams, 37.
The Lyneham crew members who died were Flt Lt David Stead, 35, Flt Lt Andrew Smith, 25, Flt Lt Paul Pardoel, 35, Master Engineer Gary Nicholson, 42, Chief Technician Richard Brown, 40, Flt Sgt Mark Gibson, 34, Sgt Robert O'Connor, 38, and Cpl David Williams, 37.
A ninth RAF man on board, Sqn Ldr Patrick Marshall, 39, was from Strike Command Headquarters at RAF High Wycombe, Buckinghamshire. Acting L/Cpl Steven Jones, 25, was a soldier serving with the Royal Signals and a passenger on the Hercules.
A ninth RAF man on board, Sqn Ldr Patrick Marshall, 39, was from Strike Command Headquarters at RAF High Wycombe, Buckinghamshire. Acting L/Cpl Steven Jones, 25, was a soldier serving with the Royal Signals and a passenger on the Hercules.
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