Sir Tim Clark received valuable backing from Willie Walsh, the head of International Air Transport Association, for Emirates airline's stance on Heathrow slashing passenger numbers.
Heathrow last week asked airlines to stop selling some tickets for summer flights, limiting the number of passengers flying from the hub to 100,000 a day to ease pressure on operations that have been unable to keep up with demand.
"We said we can't do that and we won't do that," said Sir Tim at a panel at Farnborough Airshow on Monday, days after Emirates and Heathrow Airport issued a joint statement on the crisis engulfing the UK's passenger hub.
Sir Tim criticised Heathrow managers for failing to anticipate the travel rebound until it was too late. He said Heathrow had given Emirates 36 hours from Wednesday to reduce capacity on its six daily flights, which are operated with the Airbus A380 superjumbo.
The president of the Dubai-based airline believes the badly disrupted air travel industry could return to equilibrium in 2023, but that the airlines must "tough it out" until then. Emirates could eventually look at transferring one of its six daily Heathrow flights to London Gatwick as part of an agreement to relieve pressure.
Mr Walsh, who represents the industry in his post-International Airlines Group career, said the management of Heathrow was "a bunch of idiots" for failing to foresee the recovery post-pandemic and the opening up of global business and tourism. "All you had to do was count up the tickets," he said. "Tim was selling six A380s [tickets] per day."
"I am surprised Heathrow have not been able to get their act together better than this. Airlines have been predicting stronger traffic than Heathrow has been predicting ... they clearly got it completely wrong," Mr Walsh added. "To tell airlines to stop selling — what a ridiculous thing for an airport to say to an airline."
Farnborough Airshow - in pictures
The pair were commenting after Emirates on Thursday angrily rejected demands by Heathrow to cut capacity — despite the threat of legal action. "The way we left it with Heathrow (was that) today we still have our six flights operating," Sir Tim said of the possibility of Emirates transferring one of its six daily Heathrow flights to London Gatwick. "What I needed to do with them was to look at how we can possibly switch over one of the flights into Gatwick."
Last-minute airport curbs are more complicated for Emirates than many European carriers because of the large variety of destinations served beyond its Dubai hub. This means passengers coming from across the globe can be affected, Sir Tim said.
"Anybody who does this to us obviously is going to incur our wrath ... this is totally unacceptable," he added.
"We still have to go into battle with regards to some of the draconian measures (that) they are insisting on taking and I don't really want it to get any more ugly than it has been."
The airline and airport later announced a deal to cap further sales on flights out of Heathrow through mid-August. “[Emirates] is ready and willing to work with the airport to remediate the situation over the next two weeks, to keep demand and capacity in balance and provide passengers with a smooth and reliable journey through Heathrow this summer,” the joint statement said. “Emirates has capped further sales on its flights out of Heathrow until mid-August to assist Heathrow in its resource ramp-up, and is working to adjust capacity.”
Heathrow blames airlines for failing to secure enough ground handlers. Emirates says its own ground-handling unit is ready and blames the problems on central staff shortages at Heathrow.
"Heathrow is well-prepared for this summer," an airport spokesman said. "We started recruiting security officers in November last year and will soon have as many people in security as in summer 2019.
"The fact that Heathrow’s cap is 50 per cent higher than a similar cap at Amsterdam, our nearest rival, shows how much better we have planned than our competitors.”