Originally Published: 15 JAN 24 06:22 ET

By Junko Ogura, Akanksha Sharma and Marc Stewart, CNN

Tokyo (CNN) — A domestic flight operated by Japanese carrier All Nippon Airways (ANA) returned to its departure airport on Saturday after a crack was found in a window in the cockpit of the Boeing 737-800 plane, the airline said Monday.

The crack was discovered about 40 minutes after take-off in the “second window from the right out of six windows in the cockpit,” ANA said. All 65 passengers and crew of the ANA flight 1182 arrived back safely, it added.

The crack was discovered in the outermost of four layers of tempered glass on the cockpit window, the airline said. It is investigating the cause of the crack and has reported the incident to Japan’s Ministry of Land, Infrastructure, Transport and Tourism.

Boeing’s 737-800 model has been in service since 1998 and is a workhorse in commercial aviation, recognized for its reliability and strong safety record.

But the company’s record is once again under scrutiny after a shocking mid-air incident earlier this month on a different model of the aircraft, the 737 Max 9.

On January 5, a door plug on an Alaska Airlines flight blew open mid-flight, leaving a refrigerator-sized hole in the fuselage. The door plug, a portion of the plane’s fuselage the manufacturer can put in place instead of an emergency exit door, detached from the plane and was later found in an Oregon backyard.

171 Boeing Max 9s remained grounded in the United States as of Friday as Alaska Air and United Airlines await updated emergency inspection guidance from the Federal Aviation Administration (FAA).

The FAA said last week it was opening an investigation into Boeing’s quality control due to the failure of the door plug. The National Transportation Safety Board is conducting its own investigation, separate from the FAA.

The-CNN-Wire