Air Canada offers fewer miles on discounted Tango fares. Not only do Tango fares earn fewer miles, but elite members are not eligible to be upgraded when flying in Tango. Tango Plus booking classes, however, offer 100 percent mileage credit and are eligible for upgrades.

Members booking Tango fares for flights within Canada earn only 25 percent of miles flown and zero status miles, and on flights between Canada and the U.S., members earn 50 percent of redeemable and status miles. Until now, Tango fares were not offered on most international flights, except for flights to Asia and Australia, a change that was introduced last year.

As of Oct. 16, 2012, three fare classes (T, L, K) that were previously classified as Tango Plus fares for international flights are now classified as Tango fares, which means they will only earn 50 percent of miles, including status miles. The change applies to all flights between Canada and Europe, Israel, South America, Asia and Australia. Booking classes T, L and K will continue to be classified as Tango Plus for flights within the U.S. and Canada. Air Canada Elite and Super Elite members who made international reservations for flights in T, L or K prior to Oct. 16 will be rebooked into a Tango Plus class so that they will earn as before the change. Additionally, Air Canada Top Tier and Aeroplan members will earn 100 percent status miles for these international reservations made prior to Oct. 16.

Bottom line: Aeroplan members will need to pay closer attention to their booking classes when making international reservations. Members used to be able to earn 100 percent of mileage flown, including status miles, on international flights. Now, if you book a discount coach fare that falls into the T, L or K booking class, you’ll only earn half as many miles. And if you are an elite member, you won’t be eligible for upgrades unless you book into a higher (and likely more expensive) Tango Plus booking class.