In August 2023, the UK’s air traffic control operator, NATS, experienced a major technical incident that led to the cancellation of over 2000 flights and an estimated cost of over £100 million GBP. The cause of the incident was initially attributed to a faulty flight plan. Flight plans are first submitted to a European-wide authority called IFPS, and if accepted, the flight is cleared for takeoff. The flight plan is then transferred to NATS at least 4 hours before the aircraft enters UK airspace. However, there seems to be a process that delays flight plans, resulting in NATS receiving them after the flight has already taken off. The incident report delves into the technical details of the incident, focusing on the failure of the Flight Plan Reception Suite Automated (FPRSA-R) sub-system.
https://jameshaydon.github.io/nats-fail/