Willie Walsh has said it would be "madness" for Shannon Airport to establish its own airline.
Speaking on RTÉ's Morning Ireland Mr Walsh, who is CEO of the International Air Transport Association, said airports should focus on running airports.
A Shannon Airport-run airline was suggested last week at the Oireachtas Joint Committee on Transport and Communications.
Shannon Airport's chairman designate Pádraig Ó Céidigh said such a move was possible but a "huge, huge task".
"I hear lots of crazy ideas from politicians but that’s probably one of the most crazy ones I’ve heard," said Mr Walsh when asked about the idea.
"Running airlines and running airports are two completely different things," he added.
Speaking at IATA’s World Cargo Symposium, which is taking place in Dublin today, Mr Walsh said the aviation industry still faced substantial losses as it recovered from the pandemic, but its outlook was more positive now than it was three months ago.
"2020 was a very severe downturn, the industry lost about $140 billion," he said.
"This year we’re forecasting those losses to reduce to about $52 billion, and next year, still losses but reducing again to about $12 billion. These are terrible figures - but we are seeing positive signs now, more and more countries are opening their borders," he stated.
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The IATA chief said there was some evidence that the experience of remote working and virtual conferences was leading some businesses to reigning in their aviation spending, but he felt most wanted to get back to face-to-face meetings.
Mr Walsh also reiterated his opposition to a carbon tax on aviation fuel, and said it would divert money away from the industry’s efforts to reduce its emissions.
"What we want is to decarbonise the industry, taxation just takes money out of the industry that otherwise could have gone to improving environmental performance," he said.
He also defended aviation's track record on sustainability, and said its growth expectations did not mean its emissions would grow too.
"There's a big disconnect between a growth in passengers and a growth in Co2," he explained.
"Over the past 15 years passenger numbers have grown by about 120% whereas Co2 emissions have grown by 40%. And that disconnect will continue as modern technology aircraft replace the older generation," he added.