Air passengers’ willingness to pay for ancillary services on long-haul flights

•We assess the willingness to pay for ancillary services on long-haul flights.•We implement a choice-based conjoint analysis to investigate 5 ancillary services.•Leisure passengers are willing to pay more for most ancillary services.•Millennials have a different willingness to pay than older passengers.•Flight duration has a contrasting impact on the willingness to pay.