Airbus has grounded almost 6,000 A320 aircraft worldwide after identifying a problem with the planes’ flight control computers that can occur when exposed to sunlight, the company said on Friday.

The grounding has caused widespread flight delays and cancellations, with airlines providing regular updates to affected passengers. Airbus said the A320s will return to service once a software update is implemented.

The issue came to light following an October incident in which an A320 on a flight from the United States to Mexico suddenly descended below its cruising altitude. Investigators found that sunlight had disrupted the plane’s flight control computers. A JetBlue flight on the same route had previously been struck by lightning, resulting in 15 injuries and a diversion.

Airbus is continuing to investigate the incidents to prevent future occurrences and ensure the safety of its fleet.