Tom Wagoner told KTRK-TV, Houston, he had to call his girlfriend on his cellphone to have someone get him out of his predicament Friday.
"She thought I was crazy," Wagoner said. "I said, 'Debbie I'm locked on the plane.' I said, 'I'm telling you the truth; you better go somewhere and get me off this plane.'"
United Airlines did send someone to check the parked plane at Bush Intercontinental Airport about a half hour later and found Wagoner was, indeed, locked inside.
"What if I had a medical condition or something?" Wagoner said. "What if I had a heart attack and I was dead? You just shut the plane and leave someone on there?"
Wagoner had been en route from Louisiana to California when he fell asleep. He apparently went unnoticed when everyone else, including the crew, deplaned and shut the aircraft down for the night.
"I woke up and the lights were out. I was like, what's going on?" Wagoner said.
ExpressJet, which operated Flight 4245 as United Express from Lafayette, La., to Houston, said it apologized and was looking into how Wagoner was missed before the plane was locked up for the night.