Toronto's Pearson International Airport will open a new terminal Tuesday, at a time when its biggest tenant, Air Canada, is facing an uncertain future.

Last week, Victor Li's Trinity Time Investments announced it was backing out of its planned $650-million investment in the airline. It cited union resistance to changing their pensions plans as the key reason.

But that wasn't the only reason. Air Canada faces cut-throat price competition from emerging discount operators, and a declining domestic market share.

No other investors have emerged, but if they do, they are likely to want to take another look at the pensions as well.

Air Canada's major unions said Sunday they have already made $1-billion worth of concessions in the restructuring process over the past year, in return for protection of the pension plan.

On Monday, however, the Air Canada Pilots Association broke ranks wit the four other main unions, and said it would begin its own search for a new equity investor.

Prime Minister Paul Martin suggested such accommodations were the way to go.

Martin said Transport Minister Tony Valeri is "actively" involved in the situation. He called on the airline, its unions and other stakeholders to work hard to find a "resolution to this."

The prime minister refused to speculate on whether Ottawa would deliver a rescue package, if a new investor does not come forward.

Montreal-based Air Canada has been under creditor protection since April 1, 2003. The protection was extended last week to April 15, by which time Trinity is expected to decide whether to proceed with its investment.

There are reports some of Canada's largest pension funds may step in.

The Globe and Mail reported there have been preliminary talks between the Caisse de depot et placement du Quebec, the Ontario Municipal Employees Retirement Board and the Ontario Teachers Pension Plan Board about putting in a joint bid for the airline.

Other possible saviours could include Cerberus Capital Management or that Gerry Schwartz and his Onex corporation. All declined to comment Monday on a possible investment in Air Canada.