'Black hole' still surrounds detail of Hercules deaths

The final, fatal flight of Hercules XV179 began at 1.24pm on January 30 2005 when it took off from Baghdad airport and began to fly north-west. On board was one of the RAF's most experienced crews, including the pilot, David "Steady" Stead, who was reputed to be able to turn a Hercules, not the most nimble of planes, "on a sixpence".

Five minutes after takeoff as it flew low over farmland, the plane came under fire. A fuel tank in the right wing was hit and exploded. The Hercules had time to radio ground controllers: "No duff, no duff [this is not a drill], we are on fire, we are on fire" before a 5m (17ft) section of wing broke away. Not even Stead could prevent the plane from hurtling to the ground. Witnesses spoke of a "fireball" that the 10 servicemen on board had no chance of surviving.

In the three and a half years since the plane crashed, a string of blunders that led to the downing of Hercules XV179 have emerged. For many of the men's relatives, sadness has turned to despair and anger.

First, the crew had no idea they were flying over an "ambush site". Less than three hours before the Hercules took off two American helicopters were shot at from the spot the British plane was targeted. The crew should have been warned of this. They weren't and flew straight into a trap - a "failure of intelligence" was how one senior RAF officer described this first critical error during the inquest.

Even more seriously, the crew did not know of a crucial weakness in the Hercules, a workhorse of the British airforce. Almost exactly three years before the disaster, air tactics experts had pinpointed the vulnerability of the plane's wing fuel tanks to fire when flying low and come up with a solution - the fitting of explosion-suppressant foam [ESF]. The warning was not passed on to crews and the Ministry of Defence only began to fit the foam system after the crash.

At the heart of the exhaustive inquest was who knew - and who should have known - that the Hercules was so vulnerable when flying low in hostile environments such as Afghanistan and Iraq.

A key document found during a painstaking trawl of RAF archives was from a body called the UK tactical analysis team. Dated January 2002, almost exactly three years before XV179 was brought down, it looked at points of weakness on the Hercules and concluded: "The most vulnerable area of the plane would be the fuel tanks in the wings", adding: "A potential solution to reduce risk is to retro-fit all C130 aircraft with dynamic foam for the wing fuel tanks." The Americans have had foam installed in their Hercules since the 1960s.

The Wiltshire coroner, David Masters, said he believed the report's distribution list to be "very significant". It included Strike Command - now Air Command, the RAF's headquarters - and also 2 Group, which is responsible for operating the Hercules. The recommendation also went to Permanent Joint Headquarters at Northwood, west London, and the Air Warfare Centre.

Other recommendations made by the UK tactical analysis team - such as strengthening the cockpit area with armour plating - were adopted. But the foam system was not. All Hercules now operating in Iraq and Afghanistan are fitted with ESF but nobody has still been able to say why the 2002 recommendation was not acted upon - nor even who made the decision to shelve it.

The closest the inquest got was the evidence of a retired air commodore, Peter Ollis, who was at 2 Group in 2002. He told the hearing he remembered talk of the foam but said it was not seen as a priority. And he did not recall the specific recommendation reaching his desk. He pointed out that he was in charge of 11 other types of aircraft - and at the time much of 2 Group's time was spent making sure Britain's radar was up to scratch following the September 11 attacks.

Ollis believed the recommendation would have been dealt with by a group captain - a rank below his. But no audit trail of how the recommendation progressed has been found.

Some of the bereaved relatives believe it was a question of finances - fitting a Hercules with ESF costs around £600,000 - and unsuccessfully called for a government minister to say if the foam's cost had an impact on the decision.

Another possibility floated during the inquest was that military chiefs could simply not afford to take its Hercules planes out of operation at a time when they were desperately needed in the wake of the attacks on America. John Cooper, a barrister who acted for three families, claimed in court there was a "culture of ignoring vulnerability" within the RAF at the time.

Many, including the man who led the military board of inquiry into the loss of Hercules XV179, the former Hercules squadron commander John Reid, believed the outcome would have been different if foam had been fitted. Reid said he believed the plane had come under such heavy fire that it would have been lost - but he said the foam would have given pilot Stead a little extra time to "do something". He added: "I believe it may have been different for the crew."

Reid, a wing commander, expressed anger that the known vulnerability of the Hercules to attack from the ground was not known. Hercules pilots now only fly low if absolutely necessary. "I'm... cross that the vulnerability was not known. Had it been known the crew would not have flown that profile." Amazingly he had not even heard the term ESF before the tragedy.

Despite years of searching, there remains - in the coroner's words - a "black hole". What is still not known, and may never be known, is who at a senior level in the RAF, the MoD or government knew of the vulnerability of the Hercules but decided not to act.