A member of Red Arrows air crew is believed to have been injured in an incident on the ground at the world-famous aerobatics team's base today.
Medical services were called to RAF Scampton in Lincolnshire after the incident involving one of the display team's Hawk T1 aircraft, the Ministry of Defence (MoD) said.
The MoD said the aircraft was not airborne at the time but would not confirm the condition of the crew member involved.
An MoD spokesman said: "I can confirm there has been an incident at RAF Scampton. The RAF are investigating and will provide more details when they are available."
The incident comes after Red Arrows pilot Flight Lieutenant Jon Egging, 33, from Rutland, was killed in an air show crash near Bournemouth Airport in Dorset in August.
Flt Lt Egging's wife, Dr Emma Egging, watched her husband perform with the Red Arrows just minutes before he crashed to his death.
Eyewitnesses described seeing the aircraft flying low before smashing into a field and coming to a standstill with its nose in the River Stour near the village of Throop.
The RAF temporarily halted flying of all 126 of its Hawk T1 training jets while preliminary investigations were carried out into the cause of the tragedy.
Hundreds of RAF servicemen and women joined Flt Lt Egging's family and friends at a packed memorial service for the popular pilot in Lincoln Cathedral last week.
The Red Arrows have used the dual control BAE Systems Hawk T1, which has a top speed of Mach 1.2, since 1979.
Hawk T1s are also used for training fast-jet pilots at RAF Valley in Anglesey, North Wales, and RAF Leeming, near Northallerton, North Yorkshire.
Sources said the pilot of the aircraft involved in today's incident was taken to Lincoln County Hospital.
The Red Arrows completed their final display of the season in September and are currently carrying out their winter training at RAF Scampton.
All members of the squadron change from their distinctive red outfits into green flying suits and overalls to mark the transition, according to the aerobatics team's website.
During training each pilot flies three times a day, five days a week, beginning with small formations of three or four aircraft.
Every sortie is filmed from the ground and discussed in great detail once the pilots are back on the ground.
The Red Arrows aim to fly their first formation involving all nine aircraft in the team in March.
Lincolnshire and Nottinghamshire Air Ambulance service confirmed that it was called to RAF Scampton and airlifted a patient to Lincoln County Hospital.
The service's chief executive, Peter Aldrick, said he was unable to comment on the condition of the casualty.