WestJet is pushing back its planned integration of Sunwing Airlines, which the Calgary-based carrier acquired last year. In an email, WestJet said it will weave the discount airline’s fleet into its own by April 27, 2025, six months after the integration date initially set for this October.

Rick Jones, WestJet’s interim head of route planning, told a conference Monday that the postponement relates to pilot training as well as the measurement units used in the cockpit.

WestJet says both airlines will continue with “business as usual” for their winter flight schedules.

The longer timeline means it will be nearly a year until aviators can fly each other’s planes, as pilot shortages continue to plague the industry.

Aviation expert John Gradek says wrangling over worker seniority for pilots slated to fly under the same banner remains a point of contention.