American Airlines (AAL) confirmed on Friday that it expects some operational delays as a result of a major software update affecting its Airbus A320-family fleet. Initially, the airline reported that around 340 aircraft were impacted, but after clarification from Airbus, the number was revised down to 209 aircraft.

As of 6 p.m. CT (0000 GMT), fewer than 150 aircraft still required the update. American Airlines stated that the vast majority of updates were expected to be completed overnight, with only a small number remaining to be addressed on Saturday.

The updates were mandated after Europe-based Airbus ordered an immediate software change across a significant portion of its best-selling A320 jets, following a solar-radiation event in late October that exposed a vulnerability in the aircraft’s flight-control systems.

American Airlines emphasized that the software updates are critical for safety, and the airline is working to minimize passenger disruption while complying with Airbus’ directive.