UK Flight Disruptions: Planes Grounded Due to Technical Issue

A technical issue within the UK's air traffic control systems caused flight suspensions at major London airports and other cities. The National Air Traffic Services (NATS) announced that the issue has been resolved and the process of resuming normal airport operations has begun.
Heathrow Airport reported that all departures were suspended, while Gatwick announced that the issue affected all departures across the UK. Problems were also observed at London City Airport and Edinburgh Airport.
The agency limited the number of aircraft flying in the London control zone for safety reasons.
Source: ΑΠΕ-ΜΠΕ