The Coast Guard has ended its search in the Gulf of Mexico for a missing pilot and his plane.

Officials say Bill Kinsinger, 55, took off from Oklahoma City Wednesday and was headed to Georgetown Municipal Airport, north of Austin, but diverted at some point and headed south.

Related: Animal rescue pilot missing after going unconscious over Gulf of Mexico

Coast Guard officials say they lost contact with Kinsinger after the plane flew past Freeport. The Naval Air Station Joint Reserve Base in New Orleans sent a plane into the Gulf to try and make contact with the pilot where they observed him slouched over in the cockpit.

Officials believe he was the only person aboard the privately owned Cirrus, and the pilot was unresponsive likely due to hypoxia.

Multiple pet rescue organizations tell KHOU 11 News Kinsinger is a volunteer pilot who flew several missions for different pet organizations.

The Coast Guard searched 17,458 nautical square miles for approximately 79 hours for Kinsinger and the aircraft.

“Ending a search is a difficult decision that we put the upmost thought and consideration into,” said Capt. David Cooper, chief of incident management, Eighth Coast Guard District. “Dr. Kinsinger was a well-loved man, and our hearts go out to everyone impacted during this tragic time.”