The Globe and Mail reports in its Tuesday edition that Canadians may soon pay as much as 20 per cent more to fly, adding to a growing list of travel disruptions as the Middle East war hikes jet fuel costs and threatens to drive up airfare ahead of peak travel months. The Globe's Mariya Postelnyak writes that major global carriers such as United Airlines have already acknowledged that fares may rise sooner rather than later, as have some Canadian airlines. WestJet, Porter and Air Canada are considering their ticket-pricing options, but have not yet taken action. Fuel costs amount to about 30 per cent of airlines' operating expenses, though they are just one of the factors behind air ticket prices. Violence across the Persian Gulf and the closing of the Strait of Hormuz after the United States and Israel's attack on Iran have pushed jet fuel prices up about 33 per cent compared with last summer, rising from an average 88 cents a litre then to $1.17 a litre last week. "Within the next two weeks, the first thing you'll see will be fuel surcharges," said John Gradek, who teaches aviation management at McGill. He expects added costs to appear on international flights first, followed by domestic routes about a week later.