Closure of London Heathrow following a power outage on 21 March had a €50 million ($56 million) impact on the operating profit of British Airways and Iberia parent IAG.
IAG disclosed the figure during a first-quarter briefing on 9 May, stating that the closure contributed to an overall 8.8% increase in non-fuel unit costs.
Fire at a large electricity facility known as North Hyde, east of Heathrow, resulted in the power outage.
Forensic investigation into the fire has, so far, been unable to determine the reason behind it, according to 6 May preliminary findings from National Energy System Operator.
“The root cause of the fire remains unknown,” it states.
Three transformers – designated SGT1, SGT2 and SGT3 – located at North Hyde step down voltage from 275kV to 66kV, to feed one of three substations, known as substation A, at Heathrow.
Two of the transformers, SGT1 and SGT3, are on load and the third, SGT2, serves as a standby that switches in automatically in the event of a problem.
The SGT3 transformer tripped late on 20 March, at 23:21, and the standby SGT2 became active, restoring the two-transformer supply. Firefighters were alerted to a blaze around the same time.
But 28min later, protections for SGT1 automatically disconnected both it, and SGT2, from the wider transmission system.
This cut the power to Heathrow’s substation A. Power was lost to some airport terminals and a number of shared systems for airport operations.
Airfield ring generators kicked in to maintain essential safety systems, enabling aircraft to continue landing. But since the outage was disrupting operationally-critical systems, Heathrow’s operator decided to close the airport at 01:11 on 21 March.
Heathrow engineers reconfigured the electricity network, using interconnections between the airport’s intake substations, restoring power to the terminals by 10:56 and completing a wider re-energisation by 14:23.
“Once power had been restored, there was a period of safety checking to allow all parties operating the airport to access their systems and to ensure safety critical systems were fully operational prior to passengers arriving at the airport,” says the NESO preliminary report.
Heathrow subsequently re-opened for repositioning and repatriation flights on 21 March, with normal operations restored on 22 March.
