Table 2-1 reflect the activity of U.S. passenger and cargo airlines as defined by the U.S. Department of Transportation under Chapter 411 of Title 49 of the U.S. Code.1

Throughout most of its history, the industry worked under economic and regulatory constraints intended to provide a safe and economically viable national transportation system for the traveling public. The industry experienced a degree of economic deregulation in 1978, the intent of which was to allow market forces to drive the industry to the appropriate size and economic viability. Since the industry has never been fully deregulated from an economic standpoint, the intent of that legislative action was never fully realized. Following deregulation, a number of airlines, including some of the best-known international airlines, sought economic protections under Chapter 11, merged with other air carriers, or went out of business under Chapter 7 provisions.

In the early years (1930s) of the formation of the air transport industry in the United States, aircraft and engines were experiencing exponential growth as a result of technology development. Airlines were established and went out of business with great frequency. The regulatory agency—the Civil Aviation Association—was in its early development and concentrated its efforts on establishing regulations for the certification of personnel and equipment to meet safety and standardization requirements. At that time no incentives existed for airlines to conduct re-engining or engine performance improvement studies because improved aircraft and engines were entering the marketplace continually.

In the 1940-1950 decade, the air transport industry flew aircraft developed before World War II, and since all aviation materials were committed to the war effort, little activity was dedicated to improving performance or re-engining, except for engine modifications required to maintain airworthiness.

In the next two decades, 1950-1970, the airline industry initially adapted aircraft and designs primarily developed for military applications. The last models of piston-powered aircraft stretched the limits of altitude, range, and power for the technology of the time. Individual airlines resisted, then embraced, turbojet-powered aircraft as a means to go farther, faster, and higher in order to gain their share of the transportation market. Once again, the development of structural, aerodynamic, power plant, and systems technologies regularly led to new airliners with better performance. Traditional thinking was to operate an aircraft type until a newer aircraft reached the market that provided significantly better cost or revenue generation or until the growth in maintenance cost dictated replacement (generally every 15-17 years or less). Once again, not much was known about re-engining, and engine modifications were undertaken predominately to maintain airworthiness standards.

During the 1970s and the first part of the 1980s, the airlines were in the midst of the feast-or-famine days of deregulation. For the first time ever, major air carriers were gathering the assets of other carriers as those carriers ceased to exist, in order to meet the capacity demand unleashed by relatively unrestrained growth. Significant efforts were devoted to aircraft and engine technology modifications to achieve standardization within the hodge-podge of airline fleets that was coming into being. Immediately prior to and during this period, aircraft were commonly “overbuilt” with respect to structure to overcome the limiting factors of design technology and tools and to meet the overriding requirement for long-term structural strength.

Engineering tools and technology combined during the later 1980s through 2000 to provide aircraft and engines that were optimally designed to meet the range and payload requirements of their intended use. Excess structure was eliminated, and new materials and techniques were employed to ensure that an aircraft would meet certification and service life expectations while having the lowest practical empty weight in order to reduce fuel consumption. Computer-aided design and manufacturing techniques al-


More information on Chapter 411 may be found at Last accessed on January 22, 2007.

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