The transport secretary has ordered an independent review after an air traffic control failure caused widespread disruption at Gatwick Airport, and across the UK.

Heidi Alexander said the disruption caused by the National Air Traffic Services (NATS) technical failure on September 8 was ‘completely unacceptable’.

The incident led to around 2,000 flights being cancelled across the UK, with disruption continuing after the technical problem itself had been resolved as airlines worked to get aircraft and crews back into position.

Gatwick was among the major airports affected, with passengers facing cancellations and lengthy delays.

Passengers at Gatwick Airport faced delays and cancellations, after a technical issue affected the UK's air traffic control system and caused widespread disruption nationwide. Flights resumed on Wednesday, September 9. Photo: Eddie Mitchell

placeholder image — Passengers at Gatwick Airport faced delays and cancellations, after a technical issue affected the UK's air traffic control system and caused widespread disruption nationwide. Flights resumed on Wednesday, September 9. Photo: Eddie Mitchell

NATS has now completed its report into the incident and said the outage was caused by a software defect in its flight data processing system.

Following receipt of the report, Mrs Alexander has tasked the Civil Aviation Authority (CAA) with carrying out an independent review of NATS' findings.

She said: “The disruption we saw last week was completely unacceptable and I know how frustrating it was for passengers, airlines and airports.

“I have now received NATS' report and, while I am pleased to see that the safety of passengers was protected, it’s clear we need to urgently understand why this issue was not discovered and fixed before it caused chaos.

“I have therefore tasked the CAA with conducting an independent review to check NATS’ findings and investigate their investment plans to enhance resilience in the future, along with regulatory accountability.

“It is crucial that our national infrastructure is fit for the future, and this government will make sure the aviation sector is as resilient as possible, so passengers can get to where they need to be.”

The CAA's independent review is expected to be published within six months, with its full terms of reference due to be outlined in the coming days.

The transport secretary is also expected to update the House of Commons in due course.

The development comes after flights resumed at Gatwick on the morning of September 9, following the previous day's disruption.

At the time, Gatwick warned it would take time for operations to fully return to normal.

NATS had said on September 9 that its operations were stable as it worked with airlines and airports to recover from the disruption.

It said at the time: “Our operations are stable and we continue to work closely with airlines and airports to support their recovery from the ongoing disruption to their operations.

“We would also like to reiterate our apology to all those affected – passengers, airlines and airports – by our system issue yesterday.

“While our immediate focus is on safely managing today’s flights, a full investigation will be conducted to establish what happened and identify any further action needed.”

The September 8 incident affected airports across the country, including Heathrow, Stansted and Manchester.

The UK Government said its Civil Aviation Bill, currently before Parliament, would also strengthen passenger rights and give the CAA powers to take swifter action when airlines or airports fail to meet their obligations.