Isn't very nice,and I can't speak English So I will use a translator next time, it may be a bit strange, but there is no way :( The Boeing 307 is the world's first fully pressurized passenger aircraft that has been put into use. The Boeing 307 "Stratospheric Airliner" built on the basis of the B-17 military bomber was the first commercial aircraft with a pressurized cabin, capable of cruising at an altitude of 20,000 feet (6 kilometers), known as "flying above bad weather." It has a crew of five and can carry 33 passengers, and it also has a sleeper cabin nearly 12 feet wide. The Boeing 307 is also the first airliner to have a flight engineer accompany the aircraft to take charge of technical work, so that the pilot can concentrate on flying