Bus 7 (or 3, I can't remember which is Northern Lights and which is the airport...) runs from downtown to the Airport every hour. I take it on a fairly regular basis either coming or going from the slope when I can't get a ride in the middle of the day. The downside is that it takes almost 2 hours to get from my house to the airport...which sucks when you have a 10am flight, necessitating being at the airport about 730...