The carrier, over the past several days, has had three curious incidents, all of which tie back to Boeing planes.

The oddness started last Friday, when United had to divert a flight after one of the airline’s toilets overflowed into the cabin midflight. The San Francisco–bound Boeing 777 returned to its Frankfurt origin two hours into a flight after the leakage. Before circling back, the plane spent some time circling the North Sea.

Then, on Sunday, a flight from Denver to London was forced to divert after a crack was found in the plane’s windshield. About one hour into the flight, the Boeing 787 Dreamliner changed course and eventually landed at Chicago’s O’Hare International Airport. (Passengers were booked into local hotels and rebooked on other flights the next day.)

That incident comes a little over two months after another United Airlines flight was diverted due to a cracked windshield, this one flying from Las Vegas’s Harry Reid International Airport to Washington, D.C. That jet was a Boeing 737-800.

In all of the above incidents, the planes landed safely.

Then, on Monday, the carrier’s pilots’ union shared a memo requesting pilots to consider unpaid voluntary leave in May due to delays in the delivery of new aircraft. That leave could run through the fall.

“Due to recent changes to our Boeing deliveries, the remaining 2024 forecast block hours for United have been significantly reduced,” the Air Line Pilots Association wrote, according to CNBC. “While the delivery issues surround our 787 and 737 fleets, the impact will affect other fleets as well.”

All of this comes just weeks after United announced federal regulators would be increasing their oversight of the carrier after a series of recent issues that included a piece of the outer fuselage falling off one jet, an engine fire, and a plane losing a tire during takeoff.