Passenger volumes include the combined figures for departing, arriving and transfer passengers. So for the calculation of domestic traffic throughout the entire country, each passenger is counted twice. A passenger is counted as a departing passenger at the point of departure and as an arriving passenger on arrival at the point of destination.
E.g. a flight from Helsinki to Oulu: At Helsinki the passenger is counted as a departing passenger and at Oulu as an arriving passenger. The passenger is accounted for in the figures for both Helsinki and Oulu, so that the overall passenger volume increases by two. The number of trips, however, increases by one.
Passenger figures do not include aircraft crews, infants or transit passengers.