6.2.3 Air
The primary advantage of air transportation is speed. Airlines specialise in the transport of high value goods, documents and perishable items. Generally governments of countries own the air terminals and air space and airlines purchase essential airport services, for example, fuel, storage, space rental and landing fees. Additionally, airlines need to own or lease ground handling, pickup and delivery equipment, which need to be depreciated over time. Variable costs of operation are dependent on the flying distance as aircraft are highly inefficient in the takeoff and landing phases. This means that substantial per-unit cost reductions can be gained from operating aircraft over longer distance. Also, the volume of freight carried influences variable costs. It is advantageous, therefore, to operate larger capacity aircraft. Aircraft are limited, however, by their physical configuration from carrying large volumes or a large variety of different products.