We assess the impact of bilateral air services agreements (ASAs) on air transportation using an unique dataset providing direct observations of bilateral air transport cost and time for a standardized good, for 1,190 country-pairs, between 2011 and 2015. Our results show that ASAs reduce transportation cost by 8% while they only impact transportation time for landlocked countries and RTA members. Our estimates also reveal that bilateral trade decreases cost of transport, which highlights the role of backhauling in air transportation.