LEAP 3: Safety. 1930's America, airlines are becoming big business. commercial planes flying a mixture between passenger and mail are turning a tiny profit. but commercial aircraft have yet to conquer the most important route of all. the flight across the atlantic, linking America and Europe. pan American Airlines are determined to operate the first transatlantic flights. but the challenge isn't just about building a plane that can fly the distance. the aircraft must be able to carry 4.5 tons of cargo, and 70 passengers. it must fly at 240 km per hour, against a 50 km per hour headwind. it must have the range to make the 3,100 km Atlantic crossing, without stopping. and in case the passengers are afraid of flying over nothing but sea, it must be the safest aircraft in the sky. engineers at the Boeing company, take an unconventional approach to the design of Pan Am's aircraft. they think of it, as a boat. they make the cabin the last word in luxury; with air conditioning, and a separate bar. this boat is as happy in the air, as in the water.