Airbus and European aviation regulators announced Friday that airlines must install a software update on Airbus A320 aircraft after a JetBlue plane experienced a sudden altitude drop last month. The required fix could lead to some delays as Thanksgiving travelers head home.

Airbus said its investigation into the JetBlue incident found that strong solar radiation can corrupt essential flight-control data on A320-series jets. The European Union Aviation Safety Agency issued a directive ordering carriers to apply the software correction, warning that it could cause temporary disruptions to flight schedules.

American Airlines, which operates roughly 480 aircraft in the A320 family, said 209 of its planes need the update. Most will be fixed by Friday, with the remaining few completed on Saturday. The airline anticipates some delays but aims to avoid cancellations, emphasizing that passenger safety comes first.

Delta expects fewer than 50 of its A321neo jets to be affected. United said only six aircraft in its fleet require the update and any resulting flight impacts should be minimal. Hawaiian Airlines reported that none of its planes are affected.

Mike Stengel, an aviation industry consultant with AeroDynamic Advisory, said the update can usually be completed between flights or during overnight maintenance. He acknowledged the poor timing but noted that the software patch only takes a few hours to install.

The JetBlue incident occurred on Oct. 30 during a flight from Cancun to Newark, forcing the aircraft to divert to Tampa, Florida, after at least 15 passengers were injured and taken to hospitals.

Airbus, headquartered in France and registered in the Netherlands, is one of the world’s largest aircraft makers alongside Boeing. The A320 family—whose updated version is known as the A320neo—is the main competitor to Boeing’s 737 and is currently the world’s best-selling single-aisle jet, according to Airbus.