I am debating between two connecting flights:

Thu, Apr 21 Punta Cana 1291 2:20pm 6:45pm Toronto
Thu, Apr 21 Toronto 466 8:00pm 9:01pm Ottawa
1hr15min connection

or

Thu, Apr 21 Punta Cana 1291 2:20pm 6:45pm Toronto
Thu, Apr 21 Toronto 470 11:00pm 12:01am Ottawa
4hr15min connection

I would prefer not to have a 4 hr connection time, but is 1hr 15min too short? Can anyone tell me if we go through customs in yyz?

1h15 is the exact minimum connection time. You will need to clear Canadian customs and immigration in YYZ.

I've not done an international to domestic connection, so can't comment on doability, but given there are a number of Toronto-Ottawa flights, you could risk it, with lots of some opportunity to be reaccomodated if needed.

Agree with the above - with all the frequency on rapidair(YOW,YUL,YYZ) routes, I would book the option with the lowest connection time

​​​​​​I went from my inbound US-Canada, through Customs, and to the domestic MLL in about 15 minutes at about 5:30 yesterday evening.

1h15 is tight but makeable, and if you miss it they'll just stick you on the next flight.

I had 1h30m in October, except I was heading to YVR. I barely made it in time and had to run most of way. Also had baggage I had to grab, if you don't have checked in baggage will help. The Nexus line was closed then too.

The next flight *is* the 11pm.
The risk here is that if OP books the 8pm and the 11pm is full, they will have to wait until the 12:30am.
Having said that, the 11pm is pricing much lower than the 8pm so there's probably less demand expected and it should be OK for re-accommodation.
Given the above, if it were me I would risk the shorter connection and book the 8pm.

I know, that 1230 am flight is probably ~15-20% of all the segments I've flown in the past five years.

If OP wants to book the tightest connection possible, then yeah, waiting several hours for a standby seat is what's involved in losing that bet.

To add to the above info, OP might consider two additional things:

1. Do you have a NEXUS card? If so, then the 1:15 connection is possible since NEXUS *normally* expedites your passage through customs. If you do not have NEXUS, or if for some reason NEXUS is unavailable at the time, then getting through the regular customs line *normally* takes a bit longer ... exactly how much so depends on how many other international flights arrive just before yours does, and how many other people are already in the line ahead of you. Checking the Toronto Airport website arrivals/departures page should give you some idea of how busy it will be at that time of day.

2. How does that Punta Cana flight perform in terms of operating on time? If your flight from Punta Cana arrives in Toronto 20 minutes late, for example, then obviously that will reduce your odds of making the connection. Some routes are prone to chronic delays ... you might want to see what you can find out on a resource like Flight Aware (Google it) which will let you see a history of different flights between various cities so you can spot any pattern of consistent delays. If your flight shows a history of consistently running late, then that should be a factor in your decision.

I should add that if you are delayed and have checked luggage, then there is the chance that you could still make a tight connection but your bags don't. So, there is a potential inconvenience factor in Ottawa that plays into it as well.

IF your Punta Cana flight is on time, and you have NEXUS, I'd say you're probably fine. But if you see that northbound flight has a history of running behind schedule ... or if you don't have NEXUS .... then it's inherently riskier.

Personally, I would do a bit of research and barring any clear red flags, I'd most likely book the short connection and hope for the best. If things look sketchy, then save the grief, book the longer layover and plan on having dinner at the airport while you're in YYZ.

Either way, good luck.

I have a YUL-YYZ-SJO coming up next Tuesday with a 76m connection (YUL flight leaves at 0530 arrives at 0659, SJO flight departs at 0815)

My only concern is weather delays for this, as the YUL-YYZ flight seems to arrive at D gates consistently and the SJO flights departs from the E gates which looks like it is relatively close. No customs to clear either, how long does it usually take to go from D to E?

There are 5 of us flying. We are flying in Business Class on both flights, if that makes a difference. 3 of us have Nexus, 2 don't. We will only have carry on bags.

There are 5 of us flying. We are flying in Business Class on both flights, if that makes a difference. 3 of us have Nexus, 2 don't. We will only have carry on bags.

The backup plan is the next YYZ-YOW flight. 5 seats together will be more difficult, day-of.

If 5 staying together is important (a family, say, with 1 minivan in YOW) then I'd say don't risk it. If the group can split up (business team with different drives after you land), then sure, why not? Teach those without NEXUS a lesson by being left behind.

Really good point. One of them is my mother in law. Not sure it's smart to try to teach her a lesson

There is also the possibility that one or more of the five passengers will be randomly selected for a COVID test on arrival. This is a pretty fast process, but is another thing that could get in your way.

I think what it comes down to is the mental state of the travelers.

Let's say something goes wrong and you have to wait for another flight. Will any of the travelers melt down over it? Will there be a CBC article about how one of you (ideally a veteran, or someone with cancer who finally was able to go on vacation, possibly with a puppy waiting at hone for them) was "abandoned by AC at YYZ"?

If the answer is no, you are all pretty chill, then book the short connection, understanding that it may not work out.

But if any of you much prefer the certainty of which flights they will be on, you might find a boring but drama-free longer connection is a more enjoyable ending to your vacation.

I would take the shorter connection flight. Since you are in J you will be out first and can head to CBSA quicker. Specially with only carry on. I think you already know to complete ArriveCan and have the vax proof ready and pre-dep test ready. Please also download/register with Switch Health. They are still sending a lot of passengers for random testing and if you all register in advance it will save you a few minutes each.

If it were me and I were travelling alone I would definitely risk it, but with a family group...hmm. I won't say don't do it, but I would definitely think twice. It depends on the group dynamic. Let us know what you decide and how it goes.