The number of passengers flying out of the Isle of Man decreased by about 3,000 last month as wintry conditions sparked uncertainty over flights.
Ronaldsway Airport director Anne Reynolds fears travellers may be "reverting to the habits" they showed when the airspace was clogged with the volcanic ash cloud.
She said many did not want to book in case their flight was affected.
Icy conditions caused many flights to be delayed and cancelled.
Flights to Manchester, Liverpool, Dublin, Gatwick and Birmingham were among those services affected.
Ms Reynolds added: "Whilst this is a disappointing outturn, given our recent improvements, the decrease of over 5.4% is still some 2% better than we originally forecast for November, indicating that the underlying trend towards a solid recovery is still very positive."