Transport Canada has approved the changes to Boeing Co.’s 737 Max after completing an independent review, paving the way for the aircraft to return to Canadian skies.

“This validation is an important first step in the eventual return to service of this aircraft in Canadian airspace,” Transport Canada said in a release Thursday. “However, the return to service is complex, and Transport Canada must put in place comprehensive safety plans that require additional aircraft changes, maintenance and training.”

The regulator said it expects to issue an airworthiness directive in January, which will stipulate the required design changes that must be made before the aircraft can return to the Canadian airspace.

In addition to making the modifications outlined in the directive, Transport Canada will require the incorporation of a revised pilot training program. The regulator also said airlines must conduct maintenance to the jets since they have been in storage since being grounded following two fatal crashes in 2019.

“Validation of these changes means that these modifications can be incorporated on WestJet’s 737 Max aircraft,” a spokesperson for WestJet Airlines Ltd. said in an emailed statement.

“Our Max aircraft will only return to service once all requirements are met or exceeded and we are certain they are safe and ready to return to active service in the WestJet fleet.”

U.S. regulators cleared the 737 Max to fly last month.