In Ottawa, they are not planning to include an O-Train stop at the airport because they want to send it farther out from the city centre to Barrhaven. The airport is configured in such a way that they cannot include an airport stop without making a big loop or digging a (very) long tunnel. They talked about sending a separate O-Train to the airport when they first planned the light rail system, but decided this would be too expensive. It may still happen at some point, but not right now.