Toronto airport.

Union workers at Toronto's Lester B. Pearson International Airport set a midnight deadline yesterday for a strike at Canada's busiest airport.

The Pearson airport, which handles 1,200 flights a day, is served by 56 carriers, primarily Air Canada and Canadian Airlines Corporation.

The Public Service Alliance of Canada, which represents 520 personnel including electricians, computer specialists and finance personnel, is negotiating job security, pensions and benefits.

Airport officials said they would keep the airport open -- even if workers went on strike.