Published: Apr 20, 2012 2:19 AM EDT
Updated: Apr 20, 2012 2:24 AM EDT

PENSACOLA, Fla. (AP) - The Coast Guard says a small plane has sunk into the Gulf of Mexico and that crews flying over the site saw no signs that its pilot survived the crash.

The pilot was the only person on the Cessna 421C. It went down Thursday about three hours after two F-15 fighter jets tried to make contact with the unresponsive pilot.

The pilot was identified as Dr. Peter Hertzak, a Slidell doctor.

Coast Guard Chief John Edwards said the plane landed right-side up on the ocean surface and floating, but monitoring planes did not see a life raft deploy and never made contact with Dr. Hertzak. The plane quickly begun sinking into the Gulf about 120 miles west of Tampa.