Flight plans for thousands of March Break travellers could be thrown into disarray should Air Canada's largest union launch a strike next Monday.

The International Association of Machinists and Aerospace Workers represents about 8,600 mechanics, baggage handlers and cargo agents at Air Canada.

It served notice late Tuesday that it intends to begin a strike at 12:01 a.m. ET on March 12 unless a new contract is signed by then.

In a brief statement posted on the IAMAW Local 2323 website, the union says: "We are the largest unionized workforce at Air Canada, without us, it's all grounded."

However, Air Canada executive vice-president and chief operating officer Duncan Dee attempted to downplay the possibility of travel chaos should there be a strike.

"Should a settlement not be reached and the IAMAW commences job action, the airline will endeavour to minimize inconvenience to its customers." Dee said in a statement.

"The lines of communication remain open, and we are hopeful that there remains sufficient time to avoid a work disruption."

P.O.V. Would a strike affect your March Break? Take our survey.

The Air Canada workers had rejected a tentative contract settlement signed in February and had given their union a 78 per cent strike mandate.

Many Air Canada workers are trying to win back pay and concessions they gave up to help the airline restructure under bankruptcy protection in 2003 and 2004.

In its financial report issued last month, Air Canada said it lost $60 million in the fourth quarter of 2011 and $249 million for the year.

Pension reform, wages, scheduling night shifts, mandatory overtime and the role of part-time staff are among the key issues, media reports say.

Labour Minister Lisa Raitt was reported to have said Friday that many passengers will be "coming and going from the March Break family holidays," so any that any labour disruption at Air Canada "would be most egregious."