Air Canada Saving Fuel

I was recently flying with Air Canada in the West and since a lot of the flights were short, I often ended up in a Dash-8. The Dash-8 has two turboprop engines and as soon as we landed and had slowed down to taxi to the gate, the left turboprop was turned of immediately. I met a pilot on one of the Dash-8 and he actually said that it was to conserve fuel.

I'm not sure if Air Canada is simply trying to save on fuel for money reasons, or to save the environment, but I really love to hope that it is for environmental purposes as well.