Canada's Sunwing keeps Boeing 737 MAX off its schedule until May 2020

Canadian leisure airline Sunwing said on Thursday it removed the Boeing 737 MAX jet from its network's winter schedule through May 2020, the longest of any carrier yet, as the plane's grounding drags on longer than the industry previously expected.

Sunwing said in a statement that its winter schedule, which goes into effect on Nov. 5 and runs until mid-May, is being planned without the MAX to give passengers "much-needed reassurance" while planning their winter vacations.

The MAX was grounded worldwide in March after an Ethiopian Airlines plane plunged to the ground soon after take-off, five months after a similar Lion Air fatal crash off the coast of Indonesia.

While Boeing has targeted October, the US Federal Aviation Administration has not set a timeline for the ungrounding, and it is not yet clear when the 737 MAX will fly again.

North American airlines have canceled thousands of flights and scrambled to secure additional capacity because of the grounding, with Southwest Airlines Co and Air Canada removing the MAX from their schedules until early January 2020. Other carriers, like American Airlines and Canada's WestJet Airlines have removed the MAX from their schedules until November.

"The worldwide grounding of the Boeing 737 MAX 8 aircraft created operational difficulties for us during the summer months when we did not have additional capacity within our fleet to replace this aircraft type," Andrew Dawson, president of tour operations for Sunwing, said in a statement.

"In order to maintain our customers' vacation plans, it was necessary to contract flying with third-party carriers and make schedule changes or cancellations to over 3,000 flights."

Sunwing said it would "evaluate opportunities to add capacity or reintegrate" the MAXes back into the fleet, if the planes are ungrounded during the winter.  Sunwing said its winter flights would be operated on an earlier generation of the popular 737 plane.