The Boeing Model 307 Stratoliner was the world's first high-altitude commercial transport and the first four-engine airliner in scheduled domestic service. The Boeing Model 307 pressurized cabin allowed the airplane to soar (220 mph cruising speed) above rough weather at an altitude of 20,000 feet -- higher than any other transport of its time. With names like Rainbow, Comet, Flying Cloud and Apache, the Stratoliner set new standards for speed and comfort. The Boeing Model 307 circular fuselage provided maximum space for the five crew members and 33 passengers. The nearly 12-foot-wide cabin had space for comfortable berths for overnight travelers.