Cracked cockpit window on Boeing 737 forces All Nippon Airways to turn back

Jan. 15 (UPI) -- A cracked window in the cockpit of a Boeing 737 forced a Japanese All Nippon Airways flight to turn back to the airport over the weekend. The incident comes as Boeing faces investigations into quality control after a door plug blew open mid-flight earlier this month.

Flight NH1182 "experienced a crack on one of the outermost of the four layers of the cockpit window," ANA wrote in an email Monday. "During the flight the cabin pressure of the Boeing 737-800 aircraft was normal and the landing was made under normal conditions."

The crack was discovered about 40 minutes after take-off from Sapporo's New Chitose Airport in Japan. The cabin remained pressurized and none of the 65 passengers and crew were injured.

While Boeing's 737-800 has been in service for more than two decades and is known for its reliability and safety record, all of Boeing's newer 737 Max 9 airplanes were grounded earlier this month after a door-sized hole blew open in the side of one of the planes.

Alaska Airlines flight 1282 lost the plug panel on the rear fuselage of the 737-9 Max plane several minutes after taking off from Portland, Ore., to Ontario, Calif., on Jan. 5. Several of the 171 passengers were injured as the flight returned to the airport. Alaska Airlines has offered all passengers on the flight a full refund, plus $1,500.

"This was a harrowing flight for our guests and crew, and we're grateful that all individuals have been medically cleared," Alaska Airlines wrote in an updated statement Saturday.

Boeing says of the Max 9s grounded for inspections, an unspecified number have revealed loose bolts holding similar plug panels. Until all planes are inspected, both United Airlines and Alaska have announced hundreds of flight cancelations.

While Boeing has not commented on the cracked window aboard the All Nippon Airways 737-800, the company has called the Alaska Airlines Max 9 incident the result of a "quality escape."

On Saturday, Alaska Airlines issued a statement, promising to expand its own oversight of the airline's 737s during production at Boeing.

"Starting this week, we will also enhance our own quality oversight of Alaska aircraft on the Boeing production line, expanding our team with additional experienced professionals to validate work and quality on the Boeing 737 production line."