It will be the anger of the families that grab the headlines over the Board of Inquiry report into last year's explosion of a Nimrod spy plane over Afghanistan, despite a concerted MoD attempt to defuse criticism that it sent 14 men to die in an aging aircraft. The families' anger is entirely justified.

Nimrod XV230 had just finished refuelling on September 2, 2006, when the pilot reported a fire in the bomb bay. He put out a mayday call and attempted to land at Kandahar air base but the No 7 fuel tank at the base of the starboard wing exploded and the aircraft fell apart.

It has always been suspected that the air-to-air refuelling system on the Nimrod MR2 was at the heart of the disaster that killed the crew of Nimrod XV230.

It was a quick fix solution fitted during the 1982 Falklands Conflict to get the aircraft to the south Atlantic to track the Argentine Navy and was never designed to be used in the intensive way in which it was used for aircraft flying over Afghanistan.

Using the system in this way had led to numerous leaks, not just of small amounts of fuel but of very large amounts, in one case close to 1,000 gallons. It was no surprise when the board of inquiry confirmed that it was to blame for the leaking fuel.

Excess pressure on the air-to-air refuelling system forced fuel to leak out either from the piping or the top of one of the tanks and flow into an empty area between the bomb bay and the No 7 fuel tank at the root of the starboard wing.

The source of ignition was also not a surprise. The board of inquiry pointed to the supplementary cooling pipe (SCP), a hot air pipe running between the bomb bay and the No 7 tank.

However the way in which the fuel caught fire was a shock. It had been believed until now that the hot air pipe must have fractured pouring out hot air at around 400 degrees Celsius - way above the spontaneous ignition point of the aircraft's Avtur fuel - and that this started the fire that destroyed XV230. The fire boiled the fuel in the No 7 tank until it exploded bringing down the aircraft.

But the board of inquiry found that part of the piping in the area next to the No 7 fuel tank on the Nimrod aircraft has no insulation on it. Fuel collecting on this pipe would have ignited in less than a minute.

This was on an aircraft which - given its age - was regularly monitored for safety and which was known to be prone to leakages of fuel. In the circumstances, it is a miracle that fuel had not come into contact with the pipe before.

Small wonder then that both Des Browne, the defence secretary, and the Chief of Air Staff Air Vice Marshal Glenn Torpy were quick to apologise profoundly to the families of those killed. That and the MoD's uncharacteristic rush to promise extensive compensation to the families were part of the MoD's damage limitation exercise, as was the announcement of a further, more extensive, inquiry by a senior Queen's Counsel barrister.

That of course neatly stops them having to answer any questions about the copious warnings that the RAF and the MoD received about the need to deal with the increasing dangers posed by continuing to fly the Nimrod MR2 on way beyond it's originally planned out-of-service date.

The questions the inquiry will need to answer, and which did not fall within the board of inquiry's remit, are:

— Why when a BAE Systems report warned as far back as August 2004 that there had been 880 fires or smoke-related incidents on board the Nimrod in just 22 years and that the SCP hot air pipe was too close to key areas of the fuel system, it was not taken out of use?

— Why it was not taken out of use in November 2004, when the pipe did fracture, pouring hot air onto the No 7 fuel tank?

— Why it was not taken out of use in September 2005, when the station commander at RAF Kinloss, the Nimrod's home base, warned that given the aircraft's age it was likely to happen again?

— Why when defence consultants QinetiQ expressed concern, just six months before the explosion, that leaks caused by the air-to-air refuelling system could not be replicated and were going unfixed, did the senior RAF officers overseeing the Nimrod fleet not suspend mid-air refuelling?

Indeed why was it only suspended last month, when another Nimrod suffered a major fuel leak during mid-air refuelling, put out a mayday distress call and made a thankfully successful emergency landing at Kandahar air base?

There has been much talk about the cost-cutting that delayed the aircraft's replacement until 2010, a date that is 15 years after its original out-of-service date. But stopping air-to-air refuelling and taking the SCP hot pipe out of use, both of which have now had to be done, cost not a single penny.

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