The U.S. Coast Guard searched the Gulf of Mexico Thursday for a small plane that didn't land at its scheduled location in Central Texas and stopped responding to air traffic controllers.

The pilot of a Cirrus SR-22 left Wednesday afternoon from a small airport in Oklahoma City after filing a flight plan to land in Georgetown, Texas, about 25 miles (40 kilometers) north of Austin. The pilot was flying alone.

Federal Aviation Administration spokesman Lynn Lunsford said the plane kept flying and was last observed on radar 219 miles (352 kilometers) northwest of Cancun flying, at 15,000 feet (4,600 meters).

Coast Guard spokeswoman Lexie Preston in New Orleans said Thursday that the North American Aerospace Defense Command, or NORAD, relayed to Coast Guard searchers that the pilot was the only person aboard the plane.

NORAD launched two F-16 fighters from a base in Houston and made contact with the plane, NORAD spokeswoman Maj. Mary Ricks told ABC News. The fighters performed military maneuvers in an effort to gain the pilot's attention, but the pilot appeared to be unresponsive, she said.

The plane is registered to Oklahoma-based Abide Aviation.

Preston said Coast Guard aircraft were searching a broad area Thursday off the Yucatan Peninsula in Mexico.