Why did around 6,000 A320-family aircraft need a software change in just days in 2025?

When a JetBlue A321 suffered a sudden, severe nose-down pitch on October 30, 2025, investigators quickly focused on the A320 family's flight control system. A post-incident report attributed the uncommanded descent to a failure in the backup flight control computer, the ELAC 2 unit.

The identified problem was that intense solar radiation could corrupt data used by the flight control systems. When a sufficiently energetic particle passes through a sensitive volume of a memory cell or a logic node, it can deposit charge and flip a bit. These failures could cause an uncommanded elevator movement and potentially push the aircraft beyond its structural limits.

EASA issued an emergency airworthiness directive, EAD 2025-0268-E, which made these actions legally mandatory in Europe and effectively set the global reference for the corrective action. An emergency directive is the most urgent variant: it is issued without the usual comment period and its compliance deadlines are measured in hours or "before the next flight." In this case it required replacing certain Elevator Aileron Computers, identified as ELAC B L104 units, before the aircraft's next flight. The operation takes about two hours per aircraft. The directive took effect on November 29 at 23:59 UTC. There are more than 9,500 A320-family aircraft in service worldwide. The fix required on some A320s has been causing notable logistical challenges and delays.