ANCHORAGE, Alaska — A passenger on an Alaska Airlines flight from Seattle to Anchorage, Alaska, looked up from his audio book to see a naked man yelling and heading toward the cockpit.

“I thought it was some kind of attack,” Nick Steffl said.

When the naked man reversed course Monday night and ran to the rear of the jet, Steffl confronted him. Another passenger helped restrain the man and the jet landed safely about 45 minutes later.

The man was transported to an Anchorage hospital.

Steffl, 30, was on his way to Alaska for a summer tourism job. He said Tuesday the incident in retrospect had elements of humor but was not funny high in the sky.

The man was assigned a seat two rows ahead of Steffl near the back of the jet. Steffl noticed the man watching a movie he’d seen, “The Disaster Artist.”

The movie contains a prominent scene with actor James Franco naked.

Steffl did not see the man remove his clothes but looked up to see him 15 rows ahead, running forward.

“I heard him whooping and hollering like he was having a good time, ‘Woo-hoo,’” Steffl said.

Steffl weighs about 185 pounds (84 kilograms). He guessed the naked man was about 22 years old and only about 140 pounds (63.5 kilograms). Steffl unbuckled his seat belt and stood in front of him. The young man went into “bro” mode, Steffl said.

“He said, ‘Hey man, what’s going on?’” Steffl said. “And my adrenalin is just pumping. I’m in flight response, after a guy’s running toward the cockpit after a post 9/11 flight. I was almost raging at that point.”

In a profanity-laced question, Steffl asked the man what he was doing. The man replied with a “smartass” response. Steffl slapped him.

The young man was never violent.

“I was the one that got violent,” Steffl said. “I slapped him across the face and he was like, ‘Oh, I like it.’”

Within seconds, another passenger, possibly the young man’s father, pinned his arms behind him and escorted him to the crew work area, Steffl said.

Flight attendants swarmed in and may have restrained him. Out of sight, the man shouted out crazy things the rest of the flight, Steffl said.

FBI agents contacted the man in Anchorage but left him in the care of airport police, FBI spokeswoman Staci Feger-Pellessio said.

Airport spokeswoman Trudy Wassel said airport police responded to a “medical” incident on the flight but that confidentiality rules prohibited her from additional comment.