"It is business as usual, and customers can continue to make their travel plans and book in confidence," Air Canada (ACb.TO) spokeswoman Angela Mah said in an email.

The Air Canada Pilots Association says they do not want a strike, although the pilots are voting on whether to give their bargaining committee a mandate to walk off the job.

Air Canada, the country's biggest airline, has faced several periods of disruption or near disruption over the past six months, including a three-day strike in June by customer service agents and a just-averted walk-out by flight attendants in October.

A pilots' strike or company lock-out could ground the airline as early as Friday, although the government could also pass back-to-work legislation to force pilots back to work.

Mah said talks with the airline's pilots were scheduled to continue beyond Tuesday's deadline, with the assistance of a federally appointed mediator.

A 21-day cooling off period in the talks ends at 12:01 a.m. EST (5:01 GMT) on Tuesday.

At that time, Air Canada will be in a legal position to file 72 hours notice of a lockout, meaning it can lock out the pilots if it wants to as early as 12:01 a.m. on Friday.

But Mah said the airline, which teetered on the edge of bankruptcy 2-1/2 years ago and has yet to return to profitability, had "no plans" to lock out pilots.

ACPA will be in a position to file its 72-hour notice of a strike once it has the results from its strike mandate vote, and if the pilots back a mandate. Spokesman Paul Howard said results would likely be available on Tuesday at around 5 p.m. EST.

"We will report the results of our vote tomorrow, but we are waiting to see what the corporation does as of midnight tonight," Howard said.

He said the pilots had no plans to strike and the vote was a "defensive measure in case the corporation decides to do something".

Canada's Conservative government has shown that it will not tolerate a labor disruption at Air Canada, which it regards as an important driver of economic growth. Last year, Ottawa stepped in twice to halt labor strife at the airline.

"The minister remains committed to doing what it takes to protect the public interest and help unions and employers achieve constructive labour relations," Ashley Kelahear, a spokeswoman for Labour Minister Lisa Raitt, said in an email.

Air Canada has now reached new labor agreements with all of its unions except the pilots. In a sudden burst over the weekend, it reached three tentative agreements in three days.

On Friday it agreed a deal with its mechanics, baggage handlers and purchasing agents, its biggest union, on Saturday with crew schedulers and on Sunday with its Toronto flight dispatchers.

Air Canada's shares were off 3.7 percent, at C$1.05 on the Toronto Stock Exchange on Monday afternoon. Shares of rival WestJet Airlines Ltd (WJA.TO) were nearly 3 percent firmer at C$13.70.

(Reporting By Nicole Mordant in Vancouver and Randall Palmer in Ottawa; editing by Rob Wilson and Janet Guttsman)

• A Permanent Economic Emergency