Southwest Airlines has canceled 40 flights a day since they announced their voluntary inspection program following a deadly accident aboard a plane that made an emergency landing in Philadelphia.

The airline has canceled 91 flights for Monday, according to flight tracker FlightAware. The airline has cancelled 20 flights to and from Phoenix Sky Harbor International Airport Monday. That is on top of nearly 50 flights canceled on Sunday. Additional cancellations are possible.

Southwest implemented its inspection program after the NTSB said one of the engine fan blades on Flight 1380 snapped, hurling debris that broke a window and led to the death of a passenger who was sucked partway out of the plane.

“We have minimized flight disruptions this past week through actions such as proactive aircraft routings to cover open trips, performing inspections overnight, and utilizing spare aircraft, when available,” the statement said.

The airline says they do not have cancellation predictions for the next few days as the fan blade inspections are ongoing.

“Our Technical Operations Team is working safely and diligently to accomplish the inspections as soon as possible, including during the overnight period,” Southwest says.