The CAA launched an investigation into delays at the airport after Ryanair complained that Nats, which runs the air traffic control system, had not provided enough staff to cover short and long-term absences by controllers.

Stansted also complained that a higher priority was given to managing Heathrow flights. Stansted said that on the first weekend of July last year, controller shortages meant the number of landings at the airport was reduced to 10 an hour, 65% fewer than normal.

In its report, the CAA said that although there was ‘evidence of increased delay in 2016 compared to previous years’, Nats had not failed to take ‘all reasonable steps’ to meet demand.

However, it added: ‘The CAA’s view is that delays in the London Approach Service increased in 2016 as a result of a lower resilience within the staffing of that service; put simply, there were too few operational staff available to provide normal resilience levels.’

The report blamed ‘significant’ cuts to staff levels and a higher than expected rate of short-term sickness, unplanned retirements and ‘a lack of take-up of voluntary overtime’.

The CAA has made recommendations that Nats has begun to implement.