(CNN) -- The U.S. Coast Guard has suspended its search for a pilot who for hours circled above the Gulf of Mexico in his twin-engine Cessna 421 before crashing into the water, the guard said Friday.
The plane remained afloat with its tail sticking out of the water for some time before it sank Thursday afternoon, said Petty Officer Elizabeth Bordelon, a Coast Guard spokeswoman.
The pilot is feared dead.
Pilots at Louisiana's Slidell Municipal Airport said the victim was Dr. Peter Hertzak, a cosmetic surgeon who was well known in the area.
"This is one of those unfortunate cases where even though we stood ready to respond, we were unable to effect a rescue," Coast Guard spokesman Lane Carter said Friday. "Our thoughts and prayers go out to the Hertzak family during this time."
The plane went down about 120 miles west of Tampa, Florida, at 12:08 p.m. after circling the eastern Gulf for more than two hours, said Chief Petty Officer John Edwards, a Coast Guard spokesman. The crew of a Coast Guard search-and-rescue plane watched as the Cessna made what appeared to be a soft landing, Edwards said.
The plane took off from Slidell, en route to Sarasota, Florida, with a single pilot. It had been circling at about 28,000 feet, a Federal Aviation Administration source told CNN.
The Air Force began monitoring the plane after noticing it flying erratically over the Gulf of Mexico on Thursday morning, and planes sent up to investigate reported the Cessna's windows were either iced or fogged over, Edwards said.