In November, NATS handled 181,523 flights in UK airspace, 2.3 per cent less air traffic when compared to the same month last year.
However, traffic for the year has increased by 0.9 per cent overall.
Both of NATS’ air traffic control centres handled slightly less traffic than in November last year and there was no growth at any of the 14 airports where NATS provides the service.
There was growth in some areas of the operation compared to the same month last year, with transatlantic overflights up by 3.5 per cent.
NATS handled just over 23 per cent of all the traffic in Europe in November, with 99.9 per cent of the 181,523 flights experiencing no delay from NATS.
Year to date, the average NATS attributable air traffic control delay per flight is 8.8 seconds.
Juliet Kennedy, NATS operations director, said: “We are still seeing the effects of the Thomas Cook collapse, which has contributed to the decline in air traffic in October and November.
“We do expect recovery in the coming months and we’re looking forward to a busy Christmas period and doing our best to get everyone where they need to be for the festive period.”