ABSTRACT
Purchasers of new aircraft can generally get by for seven to ten years without having to make any major structural repairs. Before deregulation, the airlines constituted a fairly stable business, and fleet decisions were much simpler, usually based on technical considerations. In the quest to achieve the lowest possible unit cost, US airlines have come to exhaust hub-and-spoke route systems where practical. During the early years following deregulation, most major carriers were reducing, and even liquidating, whole staffdepartments, including, in some cases, all their engineering personnel. Consolidation of the industry during the 1980s as a result of mergers has led to a proliferation of specific aircraft types operated by any particular carrier. One of the main reasons for aircraft purchases in large numbers is fleet commonality. Most early orders for new-generation aircraft were conceived as direct replacements of older planes—usually with models of roughly the same size.
