Three subjects have been selected for discussion in this paper, each of which has a major influence on aircraft design and operating economics. These subjects are airfield performance, noise and aircraft utilisation.

For an aircraft to have good operating economics it must be able to operate with a high load factor over a large percentage of the routes on which it is to be used. The permissible take-off or landing weight, and hence the payload, can be limited by any one of many airworthiness requirements. These include take-off distance and climb, landing distance and climb, and obstacle clearance in the vicinity of the airport.