A U.S. fighter plane crashed off the coast of northeast England on Monday, sparking a search and rescue operation for the pilot in the North Sea.

The U.S. Air Force said the F-15C Eagle crashed at around 0940 local time (0840 GMT) during a training mission.

“The cause of the crash as well as the status of the pilot are unknown at this time and UK Search and Rescue have been called to support,” it said.

A U.S. military helicopter crashed on the coast of eastern England in 2014, killing all four crew on board.