A crack was discovered in the cockpit window of a Boeing 737-800 aircraft mid-flight

• A Japanese domestic flight was forced to turn back after a crack was found in the cockpit window.
• A spokesperson for the airline said that crack was on the outermost of four window layers.
• Boeing's planes have been under scrutiny following the Alaska Airlines mid-flight blowout.

A Boeing 737-800 aircraft was forced to return to its departure airport mid-flight after a crack in the cockpit window was discovered, reports say.

The domestic All Nippon Airways Flight 1182 was heading from Sapporo-New Chitose airport to Toyama airport in Japan when the crack was discovered.

The crack was on the outermost of four layers of windows surrounding the cockpit, a spokesperson for the Japanese airline said, per Reuters.

"The crack was not something that affected the flight's control or pressurization," the spokesperson said.

No injuries reported among 59 passengers and six crew, according to the spokesperson.

All Nippon Airways and Boeing did not immediately respond to Business Insider's request for comment, which was made outside of normal working hours.

Boeing's planes have been under scrutiny after a dramatic incident onboard a Boeing 737 Max 9 operated by Alaska Airlines, when it lost part of its fuselage mid-flight had to make an emergency landing after a door plug blew out midair leaving a large hole in the side of the plane.

The incident resulted in the FAA grounding 171 Boeing 737 Max 9 indefinitely for safety checks and saying it would tighten oversight of Boeing.

Alaska Airlines and United Airlines said preliminary checks found loose parts on several grounded aircraft.

The All Nippon Airways flight was not a Max 9.