I think I mentioned it before, but I'll say it again: charter carriers are very big in the Montreal market. With Dorval handling around 9 million pax, Mirabel handles just charters and serves another 1.5 million or so pax. When you consider that Dorval's traffic is Canada/US/overseas flights, then Mirabel's share of overseas passengers is pretty significant. In terms of price, and in terms of choice of destinations in Europe, Air Transat and Canada3000 and Royal, as well as Corsair and others are very significant in the Montreal market, although frequency is admittedly not terribly high on any one route.
Noise, just to tie in the YYC/YEG/YVR flights into the YUL discussion, the point is merely that AC/LH share their YYC and YVR flights, as well as their YYZ and YUL flights, and they try to start routes with the idea of complementing each others network, not duplicating it. Also, as to LH going to YUL: rumour has it that Edmonton Airports has some interest from 'a major European carrier to start flights to Frankfurt.' That's not a particularly new rumour, and it is strictly rumour, but FWIW it could affect YUL's chances at a LH route, for better or worse.
Louis, I'd swear to seeing a LH 747 at YYC as late as '92 or '93. I'd have to go through a lot of stuff to find it, but I've got a Calgary Airport flight guide from that time period (after Calgary Airports Authority took over responsibility for the facility from Transport Canada) that lists LH as serving YYC, so LH did fly the route up until 7 or 8 years ago at least...
Alain, I'll get around to e-mailing you later, hopefully within a day or two, don't mind my procrastination at the moment