"He was scary," a witness said. "He started kicking profusely and started punching the window." Passengers on board restrained the man with zip ties and a shoelace.

A passenger on a Frontier Airlines flight bound for Houston punched a window — hard enough to break the plexiglass — as seen in a video passengers took.

A passenger aboard a Frontier Airlines flight to Houston had a violent outburst on Wednesday after being asked to move, punching and kicking in his seat until he cracked one layer of the plane’s window mid-flight.