A typical life cycle of an advanced design of transport aircraft is shown superimposed on two estimates of the limits of annual production of crude oil which might be realized from the world known and anticipated reserves. Changing the fuel used in commercial transport aircraft to hydrogen would represent an important start in the right direction. The flight was evidence of the serious interest in the Soviet Union of exploring the potential of both hydrogen and liquefied natural gas as fuel for aircraft. Hydrogen has the highest gravimetric heat of combustion of any fuel. Hydrogen can be made from water using any available energy source including nuclear, solar, wind, geothermal, hydro, and ocean thermal energy conversion; as well as being manufactured by conventional processes using the fossil fuels like coal, oil shale, and tar sands. The bars indicate the duration of typical periods for design and development, production, advanced design of large commercial transport aircraft.