Energy Saving Tips 2

By 2013 some 100 European airports will allow planes to descend all the way from cruising altitude to the runway in one smooth glide, saving up to 450 kilograms (992 pounds) of CO2 per landing, the International Air Transport Association said.
In all, airlines are hoping to save 500,000 metric tons (515 US tons) of carbon gas this way each year, said IATA's head of infrastructure Guenther Matschnigg.

http://www.usatoday.com/tech/science/environment/2009-03-31-airplane-emissions_N.htm