First: Welcome to “Airlines Unlimited”!
Here is what I think are your existing flight details:
DL175; leave ATL 8:20am, arrive LAX 10:05am: connecting to AC775; leave LAX 11:40am, arrive YVR 2:15pm.
Your connection time in LAX is 95 minutes: plenty if it was on-line (same airline), but really tight for interline and changing terminals. We could Monday morning quarterback your flight selections, but they are what they are, so you will play the hand you’ve been dealt. For what it is worth, I’ve had tighter interline connections that worked, so, if all things work well, you should be OK.
My advice is:
1. Talk to Delta at check-in in Atlanta about your connection at LAX and see if there is anything they can do for you. One remote option would be to for Delta to re-route you direct to Vancouver through Salt Lake City. DL has a connection through SLC that leaves Atlanta at 8:15am (almost the same time as your LAX flight) and gets to Vancouver (YVR) at 12:23pm.
DL415; leave ATL 8:15a, arrive SLC 10:22a: connect to DL3969; leave SLC 11:05am, arrive YVR 12:23p
That would be perfect, but it is almost certain that your existing fares will not permit this change unless you pay more, and probably a whole lot more. But asking is free, so give it a try. You could call DL in advance to broach the subject, but even if they reject you over the phone, ask again at the airport. In the event your flight to LAX is overbooked, DL might just find it to their advantage to reroute you and get you off the LAX flight. Boy, would that solve all the problems. It is a tight connection in SLC, but it is all DL so they will ensure you get to Vancouver by hook or crook.
2. By all means, try to get your Air Canada boarding passes prior to leaving ATL. Beg, cry, bribe: do everything short of hopping over the counter and printing them yourself. The last thing you want is for your DL flight to arrive on time in Los Angeles only to then be confronted with a line out the door for AC check-in.
3. If your present DL seat assignments are not toward the front of the plane, see if you can change them to get as far forward as possible. Explain your connection problem. Closer to the door means faster out the door. You are on a 767 with nearly 300 seats and there is the same single door and jetway as a 737.
4. Have Air Canada’s reservation phone number with you. If your DL flight is late out of ATL, call AC let them know. Call by cell if you are still in the airport or still at the gate with the door open, or, if worst comes to worst, call from the air using the Airphone. The number is for AC 1-888-247-2262. If AC is informed about a problem in advance, it makes life a lot easier later. If it is obvious your LAX connection is broken, then AC can start working to fix things (see #6 below).
5. When you get to LAX, hustle over to Terminal 2. Hopefully you will already have your AC boarding passes and can go straight to security and the gate. If not, head to the AC counter and, if time is tight and they have an agent working the line, see if you can be bumped-up in line. Have your passport (or birth certificates) out and ready.
6. Hopefully, you make your flight and the rest is easy. But if, after all this, you miss the flight, then your options get more complicated. You are on AC775. The next flight to Vancouver is AC777 at 3:25pm. It does not get to Vancouver until 6:07 pm, 37 minutes after the Canadian has departed (at 5:30pm). By the time you clear customs, it will probably be too late to chase down the train by cab at an outlying station. Your best bet would be to rebook a connection on AC to Kamloops, BC (YKA). AC has a connection from LAX to Kamloops through Vancouver using the same 3:25pm flight to Vancouver and arriving Kamloops at 8:28pm.
AC777; leave LAX 3:25pm, arrive YVR 6:07pm: connect to AC8201; leave YVR 7:30pm, arrive YKA 828pm
The eastbound Canadian is due into Kamloops at 1:50am.
I really hope things work out.
Bill