Engineering, fleet transition

Clearly, fleet transition is a required and almost continuous process for every airline. Yet fleet transition, with a large mxmber of operational and economic benefits, also causes some short-medium-term problems. Indeed, operational benefits translate into almost immediate economic gain however, fleet transition requires considerable plarming and investment relating to engineering, airport preparation, training and operational requirements. 

Transportation accounts for about one-fourth of the primary energy consumption in the United States. And unlike other sectors of the economy that can easily switch to cleaner natural gas or electricity, automobiles, trucks, nonroad vehicles, and buses are powered by internal-combustion engines burning petroleum products that produce carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. Efforts are under way to accelerate the introduction of electric, fuel-cell, and hybrid (electric and fuel) vehicles to replace sonic of these vehicles in both the retail marketplace and in commercial, government, public transit, and private fleets. These vehicles dramatically reduce harmful pollutants and reduce carbon dioxide emissions by as much as 50 percent or more compared to gasoline-powered vehicles. 

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