On Monday 28 August 2023, the busiest travel day of the British summer, the United Kingdom’s air traffic control system suddenly stopped working properly. A single faulty flight plan caused the failure, and the problem quickly spread across the whole country. More than 700,000 passengers had their journeys disrupted.
NATS is the company that controls the skies over the UK. It uses a computer system to read the flight plans that airlines send before every journey. A flight plan tells the system where a plane will fly and which route it will take.
That morning, the system received one flight plan it could not understand. The plan came from a French Bee flight travelling from Los Angeles to Paris. It used the same short code, “DVL”, for two different places: one in France and one in the United States. This rare combination confused the computer.
To stay safe, the system stopped working automatically. After that, controllers had to type every flight plan by hand. This manual method is much slower, so far fewer planes could take off or land. Engineers found and fixed the fault in about four hours, but the delays continued for several days.
The results were serious. Airlines cancelled more than 1,500 flights. easyJet grounded over 80 flights, and British Airways cancelled more than 60. Ryanair and many other airlines were affected too. Because the failure happened on a public holiday, thousands of families were trying to return home, and many were stuck abroad for days.
The Civil Aviation Authority, which checks that air travel is safe and fair, later studied the event. It found that about 700,000 passengers were affected. Around 300,000 people lost their flights completely, while others faced long delays. The review gave NATS and the airlines 34 recommendations to stop the same thing happening again.
The story surprised many people. It showed how one small piece of bad data can stop an entire country’s flights. Experts say modern air travel depends on computers, so these systems must be strong enough to handle unusual information without shutting down.
Key vocabulary:
- air traffic control – the service that guides aircraft safely while they are in the sky and on the ground.
- flight plan – a document that tells controllers the exact route an aircraft will follow.
- to ground (a flight) – to stop an aircraft from flying.
- Civil Aviation Authority – the official body that makes sure air travel is safe and fair.
CEFR Level B1 / ICAO Level 4