A bank holiday air traffic control meltdown that left more than 700,000 passengers stranded was made worse because a work-from-home engineers password wouldnt work.
Chaos erupted at airports across the UK last August when a flight-plan glitch caused the National Air Traffic Services (NATS) computer system to collapse.
With the system down, flights could not take off or land at any airport, causing hellish delays that lasted for days and cost airlines £100 million in compensation.
A Civil Aviation Authority inquiry into the incident today found that IT support engineers were allowed to work from home on one of the busiest days of the year.
The engineer assigned to fix the problem struggled to login remotely because the system had crashed, so it would not accept his password.
It took an hour and a half for them to get into office, where they performed a full system re-start — which did not resolve the problem.
While thousands of holidaymakers were stuck at airports or on the tarmac, advice was sought from an off-site senior engineer, who also did not understand why the system had failed so dramatically.
Passengers queue for check-in at Manchester Airports Terminal Two during the air traffic control meltdown on August bank holiday last year
Chaos erupted when the UKs air traffic control system crashed, and IT engineers were working from home so couldnt help
An information board reveals the extent of the cancelled flights as a result of the chaos
Finally, four hours after the initial incident, someone phoned the systems German manufacturer, Frequentis Comsoft, and the issue was identified.
By the time it was resolved, the backlog was so huge that many passengers did not fly until days later, so holidays were cut short or cancelled completely.
Today, the Civil Aviation Authority called for senior engineers to be on duty in the NATS offices all times to avoid a repeat of the disaster.
It also called for toothless airline regulators to be given more power to ensure customers are quickly and properly compensated — as some travellers waited many weeks, and in some cases months for out-of-pocket expenses to be refunded.
Inquiry chairman Jeff Halliwell said the incident on August 28 represented a major failure on the part of the air traffic control system.
It caused considerable distress to over 700,000 passengers and resulted in substantial costs to airlines and airports, he said.
Rob Bishton, chief executive of the Civil Aviation Authority, added: It is vital that we learn the lessons from any major incident such as this.
Transport Secretary Louise Haigh described the NATS system failure as an unprecedented event and welcomed the recommendations that regulators be strengthened.
Passengers were stranded overnight at London Gatwick Airport
An estimated 700,000 passengers were left stranded at Heathrow and other airports amid the flight disruption
She said: Ive said before that I will be the passenger-in-chief and my priority is to ensure all passengers feel confident when they fly — that’s why my department will look to introduce reforms, when we can, to provide air travellers with the highest level of protection possible.
The inquiry found the NATS system crashed while trying to process an unusual route plan for a flight from Los Angeles to Paris that would enter UK airspace.
This was because two waypoints on the journey — Devil’s Lake in North Dakota and Deauville in France — share the same three-letter code.
The system became confused because the original flight plan appeared to suggest it would leave UK airspace into Deauville before it had arrived.
Within 20 seconds of receiving the plan, the main processor and its backup had crashed when they failed to reconcile this apparently-impossible route.
Flight plan processing then revered to a manual system, meaning the number of flights being processed per hour went from 800 down to just 60.
The inquiry report said: The impact of the failure was considerable. The CAA has estimated that there were over 700,000 passengers and others who were affected by the failure, often for several days, and this had considerable financial and emotional consequences for them.
Some flights were delayed for days, and some passengers were not compensated for weeks or months
It also highlighted just how toothless UK airline regulators are.
For instance, the CAA wanted to obtain contact details for all passengers on affected flights so it could conduct a survey.
It requested this information from airlines, but they declined, with one saying that consumer research is a distraction.