Iata has downgraded its long-term passenger forecast by 400 million to 7 billion by 2034.
The revised projection reflects negative developments in the global economy that are expected to dampen demand for air transport, especially slower economic growth projections for China, according to the airline trade body.
The annual growth in demand is now set to fall from 4.1% to 3.8% but will still reach 7 billion by 2034 – twice the number expected to fly this year.
Iata director general and chief executive, Tony Tyler, said: “Economic and political events over the last year have impacted some of the fundamentals for growth.
“As a result, we expect some 400 million fewer people to be travelling in 2034 than we did at this time last year.
“Air transport is a critical part of the global economy. And policy-makers should take note of its sensitivity.
“The economic impact of 400 million fewer travelers is significant. Each is a lost opportunity to explore, create social and cultural value, and generate economic and employment opportunities.
“It is important that we don’t create additional headwinds with excessive taxation, onerous regulation or infrastructure deficiencies,” he warned.
“There is much work to be done to prepare for the 7 billion passengers expected to take the skies in 2034.”
Despite economic concerns, China is still expected to overtake the US as the world’s largest passenger market by 2029 and will account for some 1.19 billion passengers by 2034 – 758 million more than 2014 with an average annual growth rate of 5.2%.
Traffic to, from and within the US is expected to grow at an average annual growth rate of 3.1% that will see 1.16 billion passengers by 2034 or 523 million more than 2014).
India will displace the UK as the third-largest market in 2026, with Indonesia rising to number five in the world.
The prospects for more open travel between the rest of the world and Cuba and Iran offer “exciting possibilities” for business, tourism and development as diplomatic relations warm up, according to Iata.
Although Cuba is the largest Caribbean country by population, passenger growth would be from a low base of 5 million passengers to around 13 million by 2034, in the best-case scenario.
Iran, by contrast, already has a market of 12 million passengers, mostly domestic flyers.
If strong GDP growth is accompanied with a full normalisation of international relations and the end to sanctions, the total size of the Iran market could be 43.6 million passengers by 2034.
Tyler said: “There is a great deal of scope for economic development in Cuba and Iran, and air transport can play an enormous role in that.
“Relative to their economic development, the people of Iran and Cuba fly less than the global average.
“In Iran, full integration in the global economy could mean a difference in passenger growth of around 13 million extra travellers a year.”