The majority of people disrupted had their flights cancelled, diverted or delayed on Friday March 21.
A Heathrow Airport shutdown, caused by a fire at a nearby electricity substation on March 21, disrupted 270,000 air passenger journeys. 234,000 passengers had flights cancelled, diverted, or delayed on the day of the outage, and a further 36,500 were affected the following day. Heathrow's CEO will be questioned by MPs about the incident.