Two gliders taking part in the same event have crashed in separate incidents on Friday afternoon.
The first crash took place at 1520 BST when a pilot in his 50s crashed in a field near Winslow, Bucks, during a Gliding Association event in Cambs.
Thames Valley Police said he was being treated for "serious injuries".
The second glider went down at about 1600 BST in farmland near Newport Pagnell, Bucks, but the pilot is not said to be a serious condition.
A police spokeswoman said: "They are completely different crashes but both
gliders came from a Gliding Association event at Great Gransden in
Cambridgeshire."
The police are now talking to the British Gliding Club and the Accident
Investigation Board to establish the cause.