Many airlines are working to reduce the number of passengers entering and leaving Heathrow. However, Holland-Kaye said Heathrow’s latest forecast showed an excess number of seats had already been sold and therefore airlines needed to stop selling tickets now. “Even with the amnesty, daily summer departure seats will average 104,000 — giving a daily excess of 4,000 seats. On average only about 1,500 of those 4,000 daily seats have currently been sold to passengers, and for this is why we ask our partners to stop selling summer tickets to limit the impact on passengers” In 2018, the daily number of passengers passing through Heathrow was almost 220,000, split between arrivals and departures. Lufthansa ( DLAKY ), which has already canceled thousands of departures from Frankfurt and Munich for the summer season, said it may make further adjustments to its schedule “for traffic peaks in August”. “Lufthansa has made a significant contribution to the relief of airports, including London Heathrow,” a spokesperson told CNN Business. The head of the International Air Transport Association, the group representing the world’s airlines, has branded Heathrow’s travel restrictions “ridiculous”. “The airlines are anticipating stronger traffic than Heathrow had predicted … they clearly got it completely wrong,” said Willie Walsh, IATA director general. “Telling airlines to stop selling — what a ridiculous thing for an airport to say to an airline.” Walsh, the former chief executive of British Airways owner IAG, added: “Heathrow is trying to maximize the profitability they get from the airport at the expense of the airlines.” A Heathrow spokesman dismissed Willie Walsh’s comments, telling Reuters: “Aviation is under significant pressure as demand grows – at Heathrow we have dealt with 40 years of growth in just four months and what we need is collaboration and investment in services to protect passengers, not ill-informed comments from retired airline bosses.” — Sharon Browne-Peter contributed reporting.