Incident came less than two weeks after another significant failing by aviation firm Nats
Published 19th Oct 2026, 06:01 BST
An unprecedented technical fault at Prestwick caused the second major air traffic control disruption within in a fortnight which grounded more than 200 flights, the firm involved has revealed.
Nats - the former National Traffic Air Services - said the “network fault” at the base on September 21 was unrelated to the previous incident "or any previously experienced Nats technical event".
It said airports in Scotland and Northern Ireland suffered the biggest impact, and “all Scottish airports experienced periods of aircraft being held on the ground”.
However, Nats found no evidence of "malicious cyber activity, unauthorised access, or hostile intervention".
The firm’s Prestwick centre controls airspace across the northern half of the UK.
A total of 277 UK flights were cancelled on the day of the incident - nearly one in 20 of those scheduled - including at least 27 at Edinburgh and Glasgow airports, according to aviation analysts Cirium.
Easyjet - Scotland’s biggest airline - was the worst affected carrier with around 50 cancellations, followed by Glasgow-based Loganair with around 25.
The disruption followed more than 1,900 flights being cancelled, including some 120 in Scotland, on September 8 due to a “software defect” at Nats’ southern base at Swanwick in Hampshire.
The firm said the Prestwick fault, which happened just after 2.30am, had affected “network infrastructure supporting data distribution”.
Its report into the incident said: “The issue affected the automatic distribution of data supporting electronic messaging between systems and controller working positions as well as system-to-system data exchange.
“At all times, controllers could track and communicate with aircraft.
“There were no losses of aircraft separation attributable to the incident and no compromise to the safe provision of air traffic services.”
Nats said while the fault was investigated, the rate of aircraft movements was reduced to 60 per cent at 6.20am and then 40 per cent at 7.40am, with the restrictions lifted from 10am and operations returning to normal at 2pm.
It said the fault “created excessive network load and caused data exchange issues across several key operational systems”.
Edinburgh Airport - Scotland’s busiest - said 18 flights were cancelled, predominantly to and from UK destinations.
Nats said it had followed “standard processes” since the incident, including to identify improvements to its operational systems and resilience procedures.
These included “design reviews for Nats’ operational data networks to ensure similar conditions do not exist that could create similar outcomes”.
Nats said it would normally just submit such reports to the Civil Aviation Authority regulator but had “exceptionally” published the findings of the investigation into the incident “given its proximity to the previous incident on September 8”.
Chief executive Martin Rolfe came under pressure to resign after the two incidents, with Michael O’Leary, his opposite number at Ryanair Group, describing him as an “overpaid failure”.
The airline chief said Mr Rolf was “incompetent” and that his assurances after previous major faults were “worthless”.
UK Transport secretary Heidi Alexander has said she did not believe the air traffic control disruption on September 8 was “unavoidable”.