There are "clear signs" that growth in international air passenger traffic is moderating as the global economy slows, according to the International Air Transport Association (IATA).
It said that in November that the total revenue passenger kilometres operated rose 6.2pc, compared to a 6.3pc increase in October.
"Traffic is solid," said IATA director general Alexandre de Juniac. "But there are clear signs that growth is moderating in line with the slowing global economy. We still expect 6pc demand growth this year. But trade tensions, protective tariffs and Brexit are all uncertainties that overhang the industry," he added.
Global airline capacity rose 6.8pc in November compared to a year earlier, and the load factor - the percentage of available seats filled by passengers - dipped 0.4 percentage points in the month to 80pc. IATA said it's only the third time in two years that the load factor has declined on a year-on-year basis.
European carriers saw demand increase 9pc in November, which was a nine-month high, according to IATA.
"Given the mixed signs on the economic backdrop in the region, it is unclear whether this pace of growth can be sustained," warned the airline association, which represents almost 300 airlines around the world.
It added that demand in North America is supported by "comparatively strong" momentum in the US economy.
Passenger traffic in the region rose 6.1pc in November, compared to a 5.7pc increase in October, and ahead of the five-year average rate of 4pc. Capacity was 3.8pc higher in November, while the load factor increased 1.7 percentage points to 80.6pc.
In Asia-Pacific, IATA said that growth is underpinned by rising living standards and "continuing expansion of options for travellers".
Passenger traffic in the region was 6pc higher there in November compared to a year earlier, compared to 5.7pc growth in October.
Capacity increased 6pc and the load factor was flat at 79.1pc, according to IATA.