Freight/mail tonne-kilometres by air
The sum of the products obtained by multiplying the total mass of freight/mail on each flight stage by the airport-to-airport distance.
The unit of measure is the tonne-kilometer. One tonne kilometer is one tonne of cargo transported over a distance of one kilometer. In the case of multi-stage flights (flights with stops other than technical ones), the calculations should be made for all flight stages.
Urząd Statystyczny w Szczecinie