In 2023, Iata expects airlines globally to post a $9.8 billion net profit. "It’s an impressive number, particularly after huge pandemic losses," Walsh admitted.

"But a 1.2% average net profit margin is just $2.25 per departing passenger. As a return, that is not sustainable in the long-term."

The warning comes as Iata releases its May 2023 traffic data showing continued strong growth in air travel demand.

Total traffic in May 2023 rose 39.1% compared to May 2022. Globally, traffic is now at 96.1% of May 2019 (pre-pandemic) levels.

Domestic traffic for May rose 36.4% compared to the year-ago period. Total May 2023 domestic traffic was 5.3% above the May 2019 level. This is the second month in a row domestic traffic has exceeded pre-pandemic levels.

"We saw more good news in May," Walsh continued. "Planes were full, with the average load factors reaching 81.8%. Domestic markets reported growth on pre-pandemic levels."