A question mark has hung over the safety of the RAF's ageing Nimrod fleet since one of the spy planes came down over Afghanistan three years ago.
The aircraft exploded in mid-air 12 miles west of Kandahar air field, killing all 14 servicemen onboard, minutes after undergoing air-to-air refuelling on September 2 2006.
It was the biggest loss of life among British forces in a single incident since the Falklands War, and led to calls for use of all Nimrods to be halted.
But ministers insisted that they were airworthy and refused to withdraw them from service.
An inquest in May last year heard that concerns were repeatedly raised about RAF Nimrods before the crash.
In an outspoken ruling, assistant deputy coroner for Oxford Andrew Walker concluded that the entire fleet should be grounded.
He said: "The crew and passengers were not to know that this aircraft, like every other in the Nimrod fleet, was not airworthy.
"What is more, the aircraft was in my judgment, never airworthy from the first release to service in 1969."
Mr Walker also criticised what he called a "cavalier approach to safety" and said opportunities to spot the danger were missed.
The explosion was caused by fuel leaking into a dry bay and igniting on contact with a hot air pipe.
Fuel couplings should not have been in the same compartment, the inquest was told.
The crew had no means of tackling the initial flames and so were forced to attempt an emergency descent to Kandahar air base, but at 3,000ft the aircraft exploded into flames.
It broke into four large pieces and hit the ground within 12 seconds.
At the time Armed Forces Minister Bob Ainsworth refused to carry out the coroner's recommendation, sparking fury from the families of the 14 servicemen.
Mr Ainsworth said: "I have noted the coroner's comments and I will consider them carefully.
"The Nimrod is saving lives in operational theatres every day. However, if it was not safe we would not be flying it. It is safe with the measures we have taken and that is why we will not be grounding the fleet."
But in March the Government took the major step of temporarily suspending Nimrod operations overseas so all the aircraft could undergo safety modifications to replace their hot air ducts.
This work has now been completed, but at present the Nimrods are being used in and around UK air space and there are no immediate plans to send any of them back to Afghanistan.Reuse content