Calgary-based WestJet Airlines Wednesday reported a 138 per cent increase in profits in the fourth quarter, helped by stronger passenger volumes.

The company earned $47.9 million, or 33 cents a share.

WestJet earned 33 cents a share, well above the average estimate among analysts of 17 cents. (Larry MacDougal/Canadian Press)

The average estimate among analysts polled by Thomson Reuters was for 17 cents.

In the same period last year, it earned $20.2 million or 14 cents per share.

Revenue rose to $692.8 million, from $570 million a year earlier, and above the $664 million expected by analysts.

For the full year, net earnings were $136.7 million, up from $98.2 million in 2009. Revenue was $2.61 billion from $2.28 billion.

WestJet shares closed up $1.56, or 12 per cent, at $14.76 on the Toronto Stock Exchange.

The airline is projecting fuel costs to range from 82 cents to 84 cents per litre during the first quarter.

"Our controllable costs remain in check and we feel our low-cost structure and fuel efficient fleet have us well equipped to withstand fuel price volatility," president and CEO Gregg Saretsky said in a release.

Earlier this week, WestJet announced it had entered into an interline agreement with Delta Air Lines Ltd., which would allow passengers to purchase connecting flights on one ticket, receive boarding passes for all segments at their first check-in and tag bags through to their final destination.

It already has interline agreements with American Airlines, British Airways, Air France/KLM and China Airlines.

WestJet has said it aims to turn these interline agreements into full code-sharing partnerships, where each airline sells seats on the other's flights and shares the revenue. It already has a code-sharing relationship with Cathay Pacific.

WestJet model unique

"WestJet's cut a model that really no one else has done," independent airline analyst Rick Erickson told CBC News.

"Most carriers tend to join into different alliances. To have one carrier basically plugged into all the other world alliances, or the three big ones, without having to become exclusive with only one, that says a lot about that one carrier and its market reach," Erickson said.

This week, the company also boosted its schedule in the Toronto, Montreal and Ottawa corridor that's popular with business travelers.

With files from The Canadian Press