July 30, 2025

expert reaction to air traffic control issue

Scientists comment on a UK air traffic control issue which led to flight delays and cancellations.

Dr Guy Gratton, Associate Professor of Aviation and the Environment, Cranfield University, said:

“National Air Traffic Services (NATS) have said there was a fault with their radar system, and this caused a stop on departing and arriving airline traffic on Wednesday afternoon for about an hour.  They control the upper airways of the UK from two sites – Swannick near Southampton, and Prestwick near Glasgow.  It’s very integrated, and any interruption, as occurred, can only be solved in the short term by reducing the volume of traffic so as to make absolutely sure that in Britain’s very busy airways system, they achieve safe separation of all aircraft.  As the systems come back up, they have to maintain that safe separation whilst introducing new traffic back into the airways system, so even a short delay will cause disruption for some time.

“It looks to me that NATS handled this very well, with departures and arrivals only stopped for about an hour.  There’s no sign that safety was compromised, and hopefully the overnight reduction in air traffic will give them a chance to clear the disruption and recommence flying on Thursday morning with only minimal residual delays.  It’s inevitable that people directly affected are frustrated, but safety has to be the primary concern.”

Junade Ali, a Fellow at the Institution of Engineering and Technology (IET), said:

“The cause of this significant grounding of aircraft appears to be a technical issue at National Air Traffic Services (NATS).  As of 16:25, NATS report a fix is being rolled out, meaning the issue was addressed promptly.

“In late 2023, there was a similar incident related to the IT systems that NATS uses.  Given the short duration of the outage, it seems likely this is also an IT or software outage.

“NATS has previously thoroughly investigated such incidents and implemented suitable measures.  From prior incident reports, the software is understood to not compromise safety at the expense of keeping airspace open.  This is the right approach as, whilst keeping airspace open is important, the public risk appetite demands a high standard of safety when it comes to air travel.  Incidents like this remind us of the need for robust IT systems that are resilient.” 

Statement from the National Air Traffic Control Services: https://www.nats.aero/statement/statement-technical-issue-at-swanwick/

Declared interests

Dr Guy Gratton: “Current funding from EPSRC, European Commission and MoD, and I fly and teach flying in UK Airspace.”

Junade Ali: “No conflicts of interest.”