The Ministry of Defence failed to take sufficient precautions to prevent an accident where a woman was thrown from her horse, a jury has decided.
Heather Bell was a novice rider, the inquest heard
An inquest jury said not enough was done to reduce the risk of low-flying military aircraft to the public.
Heather Bell, 38, was riding with two friends in Middle Rasen, Lincs, when the horse bolted, hurling her to the ground after a Chinook passed overhead.
She was wearing protective gear but died from severe head injuries.
The jury agreed the noise from the low-flying RAF Chinook helicopter had contributed to Mrs Bell being thrown from her horse in June 2003.
The members responded to 16 questions set by coroner Stuart Fisher.
Under new inquest rules which allow a more detailed verdict where public organisations are involved, the jury at Market Rasen Festival Hall found the MoD's low-flying policy was "insufficient".
The jury had heard from witnesses and saw a reconstruction of the incident over eight days.
The MoD came in for criticism during the hearing and witnesses said the case is set to affect the way the RAF carries out low-level flying.
The hearing produced ideas, including the possibility of horse riders wearing radio beacons visible to aircraft.
The Chinook, from a base in Hampshire, had clearance to fly down to 50ft and it was travelling at 120mph.
The jury did not criticise the crew, which flew within guidelines.
Simon Bell said if one life is saved, Heather's death will not be in vain.
It recommended the MoD and RAF made more use of simulators for training.
The military services said there was a review under way of flying practices.
In a statement after the inquest, Wing Commander Jon Taylor, of the RAF Directorate of Air Staff (Lower Airspace), said: "The death of Mrs Bell was a tragedy and the Ministry of Defence extends its deepest sympathy to her family.
"We have listened carefully to the findings of the inquest and will, of course, consider very seriously the recommendations of the coroner."
Mrs Bell's family released a statement which said: "The military are apparently not subject to the full laws of the land and therefore as far as they are concerned, are not accountable for their deeds and actions.
"We have lost a much-loved daughter and a sister to her two brothers and nothing can ever take away the heartache that we feel.
The low-flying policy of Chinook helicopters was criticised.
"Our consolation is that she will always be remembered in the hearts and memories of all those who loved her."
The family revealed Mrs Bell had been an organ donor to three women. A bell at St Peter's and St Paul's Church, Middle Rasen, is to be dedicated to Mrs Bell, who was a keen churchgoer.
Her husband Simon said his 12-year-old daughter Emma would continue to ride horses and wanted to buy Midget, the horse her mother was riding when she died.
He said of the inquest verdict: "I think that anger has dissipated because we feel this inquiry has been thorough.
"That was our main objective from the start. Even if it just saves one life, her death will not be in vain.".