[Land-locked countries] Air transport is an important supplementary mode for alleviating the transit transport problems of land-locked developing countries. Up to now, outgoing air freight from the land-locked developing countries has consisted primarily of either perishable goods, such as fruit, vegetables, fishery products and flowers, or high value goods such as skins or leather, carpets and precious metals. However, because of the unreliability of surface transit transport services, a number of land-locked developing countries do airlift some of their bulkier commodities on an irregular basis. The development of air freight operations is, however, hampered by various obstacles. Considerable investments are required to extend and strengthen the runways at main international airports and to provide adequate navigational aids and cargo handling facilities. These improvements are necessary to permit the gradual introduction of the larger and newer four-engined and wide-bodied jets on scheduled passenger services: such aircraft have larger freight holds and lower costs per tonne-kilometre of capacity than those now used in many of the land-locked countries. An additional obstacle to air freight operations is the lack of an adequate surface collection and distribution system radiating from the major airport(s) of the land-locked states. Without such a system, the hinterland of the airport is severely limited and even goods travelling by air cannot benefit fully from the advantages offered by air transport. Skilled manpower constraints are also a major obstacle. Financial risks for individual airlines are great, partly because of directional imbalance in traffic, and airlines are reluctant to cooperate in land-locked countries' development plans.