The simmering dispute between Bombardier and Boeing over its CSeries jet is little more than “sour grapes” over the U.S. airplane manufacturer’s inability to sell its own rival aircraft, former Air Canada President Pierre Jeanniot told BNN in an interview.

Boeing’s complaint that its 737-800 and Max 8 planes are facing unfair competition doesn’t hold water, he said.

“Unfortunately for Boeing — and perhaps this is the sour grapes that I mentioned — that [737] smaller version doesn’t sell,“ said Jeanniot, who is currently the chairman of the Advisory Board of the Aviation Task Force at Concordia University.

“The frustration from Boeing in that situation has perhaps aggravated or increased its need to have a levy for that — and that’s just wrong.”

Bombardier is bracing for a preliminary ruling from the U.S. Commerce Department on a complaint from Boeing that accuses Bombardier of selling its CSeries aircraft below cost. The decision is expected after markets close on Tuesday.

Many expect the U.S. to rule against Bombardier. However, shares of the company spiked more than 10 per cent Tuesday afternoon on market speculation that Bombardier could prevail.

Boeing has argued that duties should be imposed on Bombardier aircraft because the Montreal-based company received government subsidies that give it an illicit toehold in the international market.  Bombardier has received a $372.5-million federal loan for Bombardier’s CSeries and Global 7000 aircraft programs, and $1 billion from the province of Quebec.

It’s been more than a year since Bombardier announced a new CSeries sale. But the company has already delivered aircraft to Swiss Air and has received interest from airlines such as Qatar Airways and Air Baltic Corp.

Earlier this week U.S. air carrier JetBlue sided with Bombardier in the dispute. The discount airline urged the U.S. regulators to deny Boeing’s petition, saying imposing tariffs on the CSeries would harm competition and result in higher airfares.

No matter how the decision comes down, Jeanniot says Bombardier will find a buyers for the innovative CSeries jet.

“There is a specific niche for that airline and I don’t think that either Airbus or Boeing are competing seriously with that airplane,” he said.