Expired!
From RedFlagDeals.com:
Planning a trip within North America between April 12 and June 18? Book your flights at AirCanada.com and pay with your VISA card, and you can save an extra 15%!
This offer is valid on Tango Plus, Latitude, and Executive Fares for flights within Canada and the US. To receive your 15% discount, you just need to enter the promotion code QCB7UHR1 when paying with your VISA card.
Book by March 15!