Software glitch halts UK flights

A legacy software defect corrupted flight data in milliseconds on September 8th, disabling the UK's air traffic control system for six hours and causing mass cancellations and delays.

“A software defect in part of the UK's air traffic control system corrupted flight data "in the space of a millisecond"”

The error went undetected for hours

The defect first occurred at 10am but wasn't declared a major incident until 12:30pm, after the system appeared to recover and then failed again.

“The error first occurred at 10am and was notified to engineers who investigated, but the system appeared to be working again, until 12.30pm when a repeat occurred”

How the software failed

When processing an aircraft code request that was paused for a higher priority task, the software didn't resume correctly, corrupting the output and affecting subsequent flight data.

“When processing of the aircraft code request resumed, the software defect meant it did not resume correctly and the resulting output was corrupted”

Hundreds of thousands disrupted

The outage lasted until 7:30pm, with over 2,000 flights cancelled and the backlog taking more than two days to clear.

Nats says safety wasn't compromised

Chief executive Martin Rolfe said the defect was unrelated to previous failures and that controllers maintained safety by conducting tasks manually throughout the outage.

“At no point last week was safety in question.”

Airlines demand accountability

Ryanair called for Rolfe's resignation after the third major UK air traffic control failure since summer 2023, while other carriers demanded compensation and a credible resilience plan.

“"The software ate my homework" is not an acceptable explanation … How many times must the UK ATC system collapse before Martin Rolfe accepts responsibility and resigns.”

Government orders independent review

Transport Secretary Heidi Alexander tasked the Civil Aviation Authority with investigating why the defect wasn't discovered earlier and whether Nats is fit for purpose.

“It's clear we need to urgently understand why this issue was not discovered and fixed before it caused chaos.”

Review will take six months

The Civil Aviation Authority's independent investigation will examine Nats' findings and investment plans to enhance resilience, with results due within six months.