Air passengers suffered major disruption on Friday due to the heatwave and a technical problem with the UK’s air traffic control system.
Just as rail delays caused by the weather were easing, travellers using two of UK’s biggest airports were warned that the extreme conditions across Europe had caused flight cancellations and delays.
And air traffic control company Nats said a technical problem with a system at the Swanwick Air Traffic Control centre had been identified shortly after noon, which was restricting the rate of arrivals.
At 3pm the firm said it had “fixed the issue sufficiently to safely increase traffic flow rates” and expected an “improving picture through the rest of the day”.
European air traffic co-ordinating agency Eurocontrol said the problem was caused by an “issue with radar displays”.
That added to the woes at Heathrow and Gatwick as they were already asking passengers to check with airlines before travelling due to heatwave-related issues across Europe.
British Airways was due to take delivery of its first Airbus A350 aircraft at Heathrow, but the flight was postponed to prioritise aircraft with passengers onboard.
Meanwhile, Network Rail engineers worked overnight to repair damage at several locations after the temperature of steel tracks soared to up to 20C higher than the air temperature, while overhead power lines also suffered heat-related damage.
Apologising to commuters for delays and cancellations, Phil James, from Network Rail, said: “I want to say sorry to passengers for the disruption and discomfort they faced making their journeys yesterday.
“The extreme temperatures made travelling by train very difficult at times and we thank passengers for their patience while we worked hard to get people moving again.
“With the railway being made of metal and moving parts, the sustained high temperatures took their toll in places.
“Everything was done to keep trains moving where possible, and last night hundreds of staff were out fixing the damage and repairing the railway ready for today.”
Having earlier warned against making non-essential journeys, Network Rail later urged passengers to check for the latest service information before they travel.
Disruption continued on Friday on the Midland Main Line between London St Pancras and Sheffield, as well as to services operated by Great Northern, Thameslink, East Midlands Trains and West Midlands Trains.
West Midlands Railway said overnight work to repair damage was continuing and many trains were starting the day out of place, resulting in some cancellations and shorter trains.
Passengers using Eurostar services to and from Paris were also facing “severe disruption” due to overhead power line problems in the French capital, the operating company said.
Four trains were cancelled and others suffered major delays.