(Reuters) -WestJet said on Wednesday it has started cancelling and consolidating flights as it prepares for a strike by its aircraft maintenance engineers and other technical operations employees.

The carrier said 6,500 customers will be impacted by 40 flight cancellations over June 18-19. On Tuesday, WestJet Airlines' mechanics gave the carrier a 72-hour strike notice.

The strike, set to begin by 9 p.m. ET on Thursday, covers about 681 aircraft maintenance engineers and other skilled employees, the union had said.

The decision to cancel flights comes as the WestJet is waiting for a response from the Canadian Industrial Relations Board (CIRB) to intervene under the Canada Labour Code, the airline said on Wednesday.

WestJet Encore operates a network of regional flights that serve the mainline WestJet Airlines. The company, owned by Onex Corp ( ONEXF ) , has been competing with rival Air Canada to meet the demands of employees to narrow the earnings gap with higher-paid peers in the United States.