PENSACOLA, Fla. - A small plane went down in the Gulf of Mexico on Thursday, about three hours after two F-15 fighter jets tried to make contact, and Coast Guard crews said they saw no signs that the pilot survived.

Coast Guard Chief John Edwards said the plane landed right-side up on the ocean surface and was floating, but monitoring planes did not see a life raft deploy or anything to indicate the pilot - the lone person aboard - was alive. The Cessna 421C later started sinking into the gulf about 120 miles west of Tampa, Fla., in about 1,500 feet of water.

A Coast Guard cutter and rescue helicopter were en route to the crash site, but not expected to arrive before the plane was well submerged.

Federal Aviation Administration spokeswoman Kathleen Bergen said the plane was flying from Slidell, La., to Sarasota, Fla.

She said controllers lost contact with the pilot at 9 a.m. The Coast Guard said it went down about 12:10 p.m.

Authorities have not identified the pilot. But Bill Huete, a mechanic who has worked on the downed aircraft at Slidell Airport, identified him as Peter Hertzak, an ob-gyn who worked in the Slidell community just northeast of New Orleans.

"I met him years ago when he was looking to start flying again and bought this plane," Huete said.

Huete described Hertzak as an excellent pilot. "He flew by the book and he didn't scrimp on maintenance," Huete said.

Huete said he went to the airport after hearing reports that identified the plane and was upset by the news.