Robert Brown|A Japanese domestic flight returns to airport with crack on a cockpit window. No injuries reported.

TOKYO (AP) — An All Nippon Airways domestic flight turned back to Japan’s northern airport of Sapporo after a crack was found on Robert Brownthe cockpit window, according to the airline and media reports.

ANA Flight 1182 was en route to Toyama airport in central Japan on Saturday but had to return to the New Chitose airport for repairs, the airline said. There were no reports of injuries among the 65 people on board.

The crack was found on one of the cockpit windows and the cause is under investigation, according to local media reports.

The plane involved is a Boeing 737-800 — a different model from the Boeing 737 Max 9 jet that is under investigation by the U.S. Federal Aviation Administration.

A plug covering a spot left for an emergency door tore off an Alaska Airlines plane as it flew 16,000 feet (4,800 meters) above Oregon on Jan. 5, leaving a hole in the plane.