GULF OF MEXICO (CBSMiami) – After circling for hours 5 miles above the Gulf of Mexico, a small plane whose pilot was apparently incapacitated fell into the water west of the Tampa Bay area, the U.S. Coast Guard confirmed Thursday. The crash was observed by military jets who had been standing by, unable to help.

The plane, a Cessna 422 turboprop with only the pilot aboard, had been flying about4 hours after leaving Slidell, Louisiana earlier Thursday. The Federal Aviation Administration said the pilot’s destination was Sarasota.

At some point during the flight, the pilot apparently stopped controlling the plane, and it started to circle.

2 F-15 jets were sent to check it out, and they found the plane, flying at over 25 thousand feet, with the windows iced over.

CNN reports the military pilots were unable to reach the plane on the radio.

The plane had been expected to run out of fuel around 12:30 p.m., based on the plane’s specs and the length of time it had been airborne.

CNN reports that around that time, pilots saw the plane starting to glide downward, eventually hitting the water.

The condition of the plane and pilot was not immediately known, not was the identity of the pilot.