The original design dates from 1965 as a 12 seat (6 rows with a centre aisle) aircraft. The aircraft was a low wing, high tail monoplane of conventional layout. Considerable attention was paid to streamlining in order to improve performance, which led to one of the design's more distinctive features, a long nose profile. The fuselage had a circular fuselage cross section to ease pressurization, allowing much higher altitude flights and consequent higher speed and comfort than competing non-pressurized designs. One drawback of the design was that fuselage was so small in cross-section that the cabin floor had to be "lowered" to allow stand-up passenger entry and egress through the rear door. This meant that the main spar had to run through the cabin, causing a tripping hazard.