<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Z-man:
I had a 767 on a YYZ-YOW flight a little while back...but I guess they were just moving the plane because it was empty and I don't think they fly that on that route regularly.</font>
Probably just a repositioning flight for YOW/LHR. Or sometimes AC pulled the originally sked aircraft for an earlier flight, they will just use what's available.