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Unless they make extraordinary efforts — for instance, going out to fly aerobatics, fly sailplanes or wander among the airstrips of backcountry Idaho — they may never develop true airmanship no matter the length of their careers.

The gliderport was popular for sailplanes in the 1920s, radio-controlled model airplanes in the 1960s and hang gliders in the 1970s, before paragliding came into vogue in the 1980s.

The sailplanes are all identical, made lightweight from foam, with radio controls and 6½-foot wing spans.

The Perlan 2 glider involved is described as a "pressurised sailplane", which can handle air density - the mass of air divided by its volume - of less than 2% its sea level reading.

Using a fiberglass glider with a 16-foot wingspan, the team hoped to set a record for autonomous flight time by a sailplane — more than five hours aloft.