Capacity is beginning to outstrip demand and airlines are seeing load factors dip as a consequence, IATA has warned.
The association said 2016 began well, with demand for flights at its strongest since 2008.
But February was the first month since mid-2015 when the number of seats available exceeded the number of passengers to fill them.
IATA statistics show capacity increasing by almost 10%, leading to a drop in load factor of 0.7 percentage points to 77.8%.
IATA's director general and CEO Tony Tyler said: "It is unclear whether this signals the start of a generalised downward trend in load factor, but it bears watching."
European airlines saw demand rise 7.7% in February compared with a year ago, but capacity was up 7.8%, leading to a 0.1 percentage point dip in load factors to 78.3%.
African airlines saw the greatest rise in traffic, which was up by 12.7%, but as capacity shot up by 13.4%, load factors fell 0.4% percentage points to 63.7%.
North America saw the slowest rise in traffic. It was up by just 3.6% while capacity was up by 4.8%, leading to a 0.9 percentage point drop in load factors to 75.9%. www.iata.org
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