Police and RAF officials are investigating reports that a collision between a horse and two cars - which killed the woman rider - may have been caused when the animal was startled by a military aircraft.
Melanie Dodds, 39, died in the accident at Caerwent in Monmouthshire on Wednesday.
A Ministry of Defence spokesman said: "An investigation into the possible involvement of a military aircraft is being carried out by the RAF police and Gwent constabulary. RAF pilots are mindful of their responsibilities."
Mrs Dodds, who had two children, was riding with a friend on a bridle path next to the A48 when the accident happened.
A witness, Stephen Davies, 47, said: "A helicopter came in very low over the trees just before the accident. It was virtually taking off the chimney pots, and that spooked the horse, which sent it out into the middle of the road with its rider."
Mrs Dodds' pony, a Welsh cob called Ed, ran into the road and was hit by a Mazda 323 and a Renault. The drivers were not injured.
The horse was put down because it was seriously injured in the accident. Mrs Dodds was taken to the Royal Gwent Hospital, Newport, where she was pronounced dead.
Huw Edwards, the MP for Monmouth, called for an investigation into low-flying military aircraft in the area.Reuse content