ACE Aviation Holdings, parent of Air Canada, canceled a $6.1 billion plane order with Boeing after the airline’s pilots rejected a contract to fly them.

Air Canada’s pilots voted Saturday against an agreement endorsed by union leaders that would have altered how the airline links wages to the size, speed, weight, and revenue potential of planes they fly. That prompted the airline to cancel the order for 18 Boeing 777s and 14 787 Dreamliners.

The cancellation of the April 25 order, the second-biggest for the 787, may slow Boeing’s attempt to regain its position as the no. 1 maker of commercial planes from Airbus. As of June 16, Boeing had 128 orders for the 787 and 401 total aircraft orders this year, compared with 451 for Airbus.

“It hurts, but it was part of a string of important victories over the last couple of months,” Richard Aboulafia, vice president of the Teal Group, a Fairfax, Va.-based consulting company, said in a telephone interview. “I doubt that this is a completely settled matter.”

For ACE, which emerged from bankruptcy in September, it means Air Canada won’t have access to a plane that’s as much as 30% cheaper to operate than the Boeing 767 it was to replace.

ACE calculated it would save about $244 million in fuel costs from the planes by 2010. Fuel accounted for 18% of the airline’s operating costs last year.

“Clearly we are disappointed,” ACE spokeswoman Laura Cooke said yesterday. “We are going to look at used aircraft” to update the Air Canada fleet.

There is no penalty for scuttling the order, Boeing’s first from Air Canada since 1989. Negotiators for the Air Canada Pilots Association reached a deal with Montreal-based ACE on June 9 before putting it to a vote of the union’s 3,000 members.

Ms. Cooke said she wasn’t advised of any new talks. A call to pilots’ union spokesman Peter Foster wasn’t returned.

The Air Canada deal included an option to buy 18 Boeing 777s and 46 787s.

The twin-aisle 787, introduced in 2003, is more fuel-efficient than existing models, because about 50% of the new plane by weight will be made from carbon fiber composites, making the plane lighter. It’s being marketed to replace Boeing’s older 757 and 767 aircraft.

“We believe we will have many opportunities to place the aircraft tagged for Air Canada elsewhere,” Boeing spokesman Todd Blecher said. “I would point out that we are seeing very strong demand for the 777 and 787.”

Air Canada would have taken delivery of the first 777s in 2006 and the first 787s in 2010.

The contract rejection “isn’t material to our business plan,” Air Canada chief Montie Brewer said yesterday.