A Royal Air Force plane carrying the Princess Royal to engagements in Scotland has been involved in a near-miss with another RAF aircraft.
Princess Anne was en route to engagements in Scotland
Princess Anne was on her way to events in Banffshire and Aberdeenshire.
The Ministry of Defence said the incident involved a Eurofighter Typhoon and happened in Lancashire's Morecambe Bay area, shortly before 1000 GMT.
The MoD said the aircraft did not collide but had infringed "buffer zones" built into their flight paths.
A spokeswoman said that both aircraft had had a specific separation distance agreed between them, but confirmed one had breached that space.
An MoD spokesman told BBC News: "A loss of separation was reported by the National Air Traffic Service to the Civil Aviation Authority between two aircraft - an RAF HS125 and a Eurofighter Typhoon."
Buckingham Palace confirmed that the 54-year-old princess had been involved in an "air proximity incident".
It is understood the RAF HS125, on which Princess Anne was travelling, was flying at a level height on a cleared flight path when the RAF Eurofighter Typhoon, flying under military control, came within 3.3 miles of it.
A warning system sounded and the National Air Traffic Services' Manchester area controller advised the HS125 to descend.
A spokesman for the National Air Traffic Services (Nats) said the royal plane was being controlled by
Nats' Manchester area air traffic control centre.
"The controller observed the Typhoon turn to cross ahead of the royal flight and immediately told the royal flight to take avoiding action," he said.
Princess Anne, the Queen's only daughter, was on board the Royal Squadron plane en route to Portsoy in Banffshire where she was visiting a sports
It is understood the princess has carried on with her engagements in Scotland.
The Royal Squadron carries members of the Royal Family and senior politicians, including the prime minister, to official engagements.
It is operated by the RAF and succeeded the Queen's Flight.
Eurofighter Typhoon planes, which were built by BAE Systems, are currently being introduced by the RAF.