In the wake of recent major , including , , and the debacle that was , it isn’t a good time for further failures by the company. that would , an unrelated 737-800 with a cracked windshield, became international news this weekend.

The flight took off from Sapporo-New Chitose airport bound for Toyama, but reversed course after the crack was discovered in the outer layer of window. The pilots landed the plane safely and none of the 65 onboard were injured. Alternative flights were arranged for the passengers to reach Toyama.

“The crack was not something that affected the flight’s control or pressurization,” a spokesperson for the airline said.

The cause of the crack is not known. The reached out to John Strickland, an aviation expert, to ask about potential causes for the crack.

“These things do sometimes happen, something may have struck the window, for example a bird, a large hailstone, it’s not unheard of. You might occasionally get a stress fracture too, from wear and tear, but that’s very rare.”

A cracked windshield in a pressurized aircraft is quite a cause for concern, despite this plane reaching its destination without further issue. A crack can compromise the pressurization, and usually requires pilots to decrease the vessel’s pressure and descend immediately. An airplane windshield is comprised of four layers, including an outer acrylic layer, a glass layer, a flexible mid-layer, and an inner acrylic layer, usually with an internal heating element for de-icing as well. In this case it was the outermost layer that had cracked, and the plane maintained its pressure throughout the flight.

ANA will likely have to replace the entire window, not just the outer layer, to ensure the windshield is strong enough to return to service.