ABSTRACT
There have been extraordinary changes in the machines that affect our daily lives. The equipment has become more complex, more sophisticated, and more automated than before. In commercial aviation for example, two pilots were needed to fly the first commercially successful air transport aircraft, the Douglas DC-3, an aircraft that was designed over 60 years ago. The DC-3 could carry about 30 passengers at a speed of about 150 miles an hour, several hundred miles without refueling. Today, two pilots are also needed to operate a commercially successful aircraft, the Boeing 747, but this aircraft transports over 400 passengers, several thousand miles, at speeds in excess of 500 miles an hour. Although the acquisition and operating costs of the 747 are many times those of its predecessor, the perseat operating costs are lower. This has helped to make air transportation affordable to many more people than in the DC-3 era.
