Canada’s two largest airlines, Air Canada and Westjet, have grounded their Boeing 737 Max fleets until late June in response to the latest estimate put out Tuesday by the airplane manufacturer.

Boeing has told airlines not to expect the 737 Max to return to service before mid-year, leaving Canada’s major airlines facing the prospect of another busy summer season without their showcase single-aisle aircraft.

“We are informing our customers and suppliers that we are currently estimating that the ungrounding of the 737 MAX will begin during mid-2020,” Boeing said in a statement released Tuesday. “This updated estimate is informed by our experience to date with the certification process.”

The 737 Max has been grounded around the world since March 2019, after a pair of fatal crashes linked to software used to control certain elements of flight on the state of the art plane. Even a June certification would mean airlines would be without one of the world’s hottest sellers for 15 months, and possibly for the second summer in a row.

In response to Boeing’s announcement, Westjet said it would remove its 13 Max aircraft from the schedule until June 24.

“We thank our guests for their patience and our WestJetters for their commitment to keeping our airline moving safely and on time as we continue to adjust our schedule,” said Ed Sims, WestJet President and Chief Executive Officer. “We remain confident in the regulatory process undertaken by the Federal Aviation Authority (FAA) and Transport Canada to ensure the safe return of the aircraft.”

Rival Air Canada was to have 50 Max aircraft in its fleet by summer 2020, replacing older Airbus A320 models. They have been removed from the schedule until June 30.

Both airlines have responded to the crisis by changing their schedules, dropping flights, substituting aircraft, and keeping older jets in their fleets.

Sunwing has four Max aircraft in its fleet.

“We acknowledge and regret the continued difficulties that the grounding of the 737 MAX has presented to our customers, our regulators, our suppliers, and the flying public,” said Boeing.

Boeing cautions even Tuesday’s announcement is a best guess of when regulators might allow the plane to fly again.

The company has already warned airlines it will recommend pilots get simulator training as a condition of returning the Max to service, an expensive proposition, though one Air Canada will find easier to meet. Since the Max was new to the fleet, Canada’s largest airline also acquired a pair of simulators, unlike other airlines that transitioned pilots from older 737s to the Max without simulator time.