In this week's issue of Ride On, Michaelle Tuz-Atkinson and I focus on market definition in the airline industry, based on my experiences with airline cases (such as the Air Canada predation case) at the Competition Bureau. We also wanted to demonstrate that with a solid understanding of the industry, the case law, and the academic literature, it is possible to reliably define these markets when data is too difficult (if even possible) to obtain -- which is often the case.