 as in the historical case of a British Air Ministry specification, or fill a perceived "gap in the market"; that is, a class or design of aircraft which does not yet exist, but for which there would be significant demand.Another important factor that influences the design of the aircraft are the regulations put forth by national airworthiness authorities.Airports may also impose limits on aircraft, for instance, the maximum wingspan allowed for a conventional aircraft is 80 m to prevent collisions between aircraft while taxiing.