On the 12th of December at 3:24pm, NATS, the UK-based global air traffic management company, confirmed that  a system outage occurred at Swanwick air traffic control centre. “The outage made impossible for the controllers to access data regarding individual flight plans and UK airspace has not been closed, but airspace capacity has been restricted in order to manage the situation”.

On the 14th of December, NATS declared  in a statement that the “back-up plans and procedures worked on Friday exactly as they were designed to and the NATS system was back up and running 45 minutes after the event the failure“.

Ok, so why the Transport Secretary, Patrick McLoughlin, has described the shutdown of much of southern England’s airspace as “simply unacceptable“?

According to the NATS  annual report and accounts 2014, NATS “operates under licence from the Secretary of State for Transport“.

On page 35 of the same report, chapter “Principal risks and uncertainties”, the very first item mentioned under “Loss of service from an air traffic control centre”, is “result in a loss of revenues” and also that  “NATS has invested in developing contingency arrangements which enables the recovery of its service capacity“.

Later on, under the “Operational systems’ resilience” section, we can read that in order “to mitigate the risk of service disruption, NATS regularly reviews the resilience of its operational systems“.

It is very surprising that the loss of revenues is mentioned whereas nothing is included on Service Level Objectives/Agreements (SLO, SLA) and Recovery Point Objectives (RPO).

In their statement,  NATS mentions that their systems were back up and running 45 minutes after the event.

According to the FT, “Air passengers faced continued disruption into the weekend even after Nats declared its systems were back to full operational capacity. A spokesman for Heathrow said 38 flights were cancelled before 9.30am on Saturday “as a knock on from yesterday”.

From a Service impact perspective, the service coulld’t be called ALL CLEAR until at least  the 13th of December at 9:30am when 30 flights were still cancelled. Therefore the service impact was at least of 18 hours, but we will need the full investigation to find out the full extent of the problem.

What does it mean that  “back-up plans and procedures worked on Friday exactly as they were designed to”? It means that the investment decisions, risk assessments, business recovery plans were designed, validated, tested and approved for at least 45 minutes system outage with reduced capacity. 

According to Telegraph.co.uk, “Britain is now the only country that is using the 1960s software. It is due to be replaced with a new system from a Spanish company in about two years, but until then they will just have to manage.”

At least we know!