The Coast Guard said it has ended a search for a missing Oklahoma City pilot and his Cirrus aircraft on Monday in the Gulf of Mexico.

Dr. Bill Kinsinger, 55, was last seen on Wednesday. Family members said he left from Wiley Post Airport to pick up a rescue dog in Georgetown, Texas.

The Coast Guard said it searched a total of 17,458 nautical square miles for about 79 hours since then but has now stopped.

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

Experts believe Kinsinger likely suffered from hypoxia while behind the controls. The aircraft was last observed on radar about 219 miles northwest of Cancun at 15,000 feet.

No other information has been released at this time.