On Thursday 14 September dozens more flights and thousands more passengers faced cancellations, long delays and diversions due to air-traffic control staff sickness at London Gatwick airport.
The Sussex airport normally has the busiest runway in the world. But with fewer flights able to land, disruption quickly took hold.
For passengers and airlines using Gatwick, it was the third failure involving the air traffic control service, Nats, in 18 days.
One Tui passenger from Kefalonia to Gatwick, Richard from Tunbridge Wells, told The Independent: “Just as we thought we were coming into land at Gatwick the pilot tells us we’ve been diverted and are landing at Bournemouth.
“We then sat in the plane for three-and-a-half hours. A complete and utter shambles: got home at midnight instead of 6pm.”
Ryanair’s Michael O’Leary has called on the head of Nats to resign “and hand the job over to someone competent enough to do it”.
So what went wrong – and could it happen again? These are the key questions and answers.
What was the problem – and the effect?
On Thursday afternoon one of the three controllers working in the Gatwick control tower fell sick. The “short-notice staff absence”, as it was described, caused “temporary air traffic control restrictions” that reduced the rate at which incoming aircraft could land.
Cutting the “flow rate” of arrivals had an immediate effect: at least 15 flights were diverted to airports as far away as Brussels and Cardiff, while dozens more were cancelled or heavily delayed.
Late on Thursday night the airport said an additional air-traffic controller was “in place”, with restrictions easing and more aircraft able to arrive and depart.
But in total at least 5,000 people began Friday 15 September a long way from where they intended to be.
The economic and emotional price of such disruption is high: costing airlines six-figure sums in passenger care, and wrecking holiday, family and business trips.
As a result, many people have expressed astonishment that there is not at least one standby controller sitting in the next room drinking coffee, poised to take over if one of their colleagues is taken ill. That sounds a reasonably simple and inexpensive “insurance policy”.
Yet as is often the case, reality is more complicated.
What does Nats say?
Nats, the air-traffic control service provider, has already accepted responsibility for the complete UK-wide failure of its IT system due to an anomalous flight plan on August bank holiday Monday, 28 August. That outage triggered more than 2,000 flight cancellations.
At Gatwick, staff shortage on 6 September again affected thousands of travellers.
After the latest bout of disruption on 14 September, an Nats spokesperson said: “We apologise very sincerely to everyone who has been inconvenienced.
“We are working closely with Gatwick Airport Ltd to build resilience in the airport’s control tower.
“New air traffic controllers have been recruited since last summer, increasing our presence by 17 per cent, and others are due to start after completing their training, in line with the agreed plan when Nats took over the contract last October.”
Who ran air-traffic control at Gatwick before Nats?
While national air-traffic control is a natural monopoly, individual airports are allowed to choose their own provider for “terminal air navigation services” (Tans). For example Birmingham, Edinburgh and Liverpool John Lennon airport use alternative Tans providers.
In 2014, Gatwick chose a bid from the German air-traffic control provider DFS Deutsche Flugsicherung. After unsuccessful legal challenges from Nats, the new provider started operating the control tower at Gatwick airport in 2016 under the name Air Navigation Solutions.
The contract was not without its problems: one day in July 2019, for example, Gatwick’s runway was completely closed for two hours due to a control tower issue, triggering dozens of diversions.
After six years, Gatwick reappointed Nats. At the time, in October 2022, Nats and Gatwick airport agreed a plan to build staffing numbers. The statement that the airport issued on Thursday night was something of a defence of Nats, describing it as “a world-class provider of air traffic services” and saying “Gatwick’s senior management recognises how hard the airport’s air-traffic controllers are working to keep the operation moving”.
While Covid was not a direct factor – Nats retained all its front-line staff during the pandemic – the worldwide near-shutdown of aviation hampered training.
Both parties say they are working hard “to ensure disruption is kept to a minimum”. More trainees will soon earn aerodrome validation, thus increasing the available staff.
Can’t they just bring someone in from another airport?
No. Each airport has its own stringent training requirements. Deep local knowledge and experience are essential.
What do the airlines say?
While the problem was with the Nats operation, the impact falls on airlines and their passengers. When an airline cancels a flight for any reason, it must provide hotel rooms for passengers, and source and pay for alternative flights.
The airlines are collectively furious that there is not better protection of the world’s busiest runway. Tim Alderslade, chief executive of Airlines UK, the industry body representing UK-registered carriers, said: “The delays we are seeing at Gatwick are not acceptable and the travelling public deserve better.
“Nats consistently reassured airlines, airports and the government that it could deliver this summer. This was clearly not the case.
“This latest round of disruption cannot go on and there needs to be a deep review of how Nats works to ensure that it delivers robust and resilient services for the UK public.”
Michael O’Leary, chief executive of Ryanair, called on the Nats CEO, Martin Rolfe, to resign and said: “Airlines are paying millions of pounds to Nats each and every year and should not have to see their passengers suffer avoidable delays due to UK ATC [air traffic control] staff shortages.”
Johan Lundgren, chief executive of easyJet, said: “Persistent staff shortages at Nats have plagued the industry and repeatedly let down customers all summer, having caused more than a month’s worth of disruption.
“This cannot be allowed to continue. Immediate action must be taken to fix the staffing shortages.”
Might it happen again next week?
Possibly. As with air-traffic control providers across Europe, there is an acute staffing problem at Gatwick. Nats says it is “working to the plan agreed with them when we took over the contract in October 2022”. Resilience should start to improve from early 2024.
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