I dont know what you mean by next fall, but apart from Sep.6,7,23 I can see a business class seat EVERY DAY for September and October, mostly via Montreal or Brussels, but also via Philadelphia/Charlotte

The website will try to keep you on Air Canada flights, because those cost more, as Aeroplan scams extra money from you for them in the way of a "fuel surcharge" lumped with taxes, so most people have no clue they are paying it.