Can I skip the final segment of my returning layover flight?

Can I leave on my returning layover flight?

Yes and no.

This technique is called "hidden city ticketing" and I recommend reading up on this either on stack exchange or googling it.

In a nut-shell: the airlines artificially inflate prices on non-stop routes where they have a monopoly and try to protect this pricing by enforcing bizarre rules. Passengers try to get around it and the airlines don't like it.

It's not illegal and nobody will physically prevent you from doing it. However it violates the terms and conditions of the airline carrier that you accepted when you bought the ticket. In some cases the airline will try to inflict some punishment on you. This can range from wiping out your status or rewards miles to actually dragging you to court. The latter though is extremely rare and so far no airline has actually achieved a conviction.

Other points to consider: If you try to skip a leg on the outgoing flight, the airline will cancel your remaining ticket. You also need to be able to access your checked luggage (if you have any). In your specific case, that's not a problem since you need to clear US customs in Detroit anyway.

Overall: if you don't care about future relationship with this particular airline, you can do this. If you are planning to use them in the occasionally or regularly, I wouldn't.

Congratulations. You have invented "hidden city ticketing" :)

Airlines hate it. For marketing reasons, going A-B-C is often priced lower than A-B. Sometimes the low fare is due to a subsidy by City C.

Here are the usual gotchas, but you happen to be in a sweet-spot where it's going to work.

• If you miss any segment, airlines will cancel the rest of your travel segments. You'd be dropping the very last leg of your trip.
• Your checked baggage may go on to your ticketed destination (C). All your baggage will be in your hands because of the need to clear US Customs.
• They can reroute you via a different B city and leave you really up the creek. Your "C" destination of Toronto is workable for you. Worst case, go downtown and hop a VIA train to Windsor.
• They can wipe out your frequent flyer miles. (don't link an account)
• They can ban you (don't do it a lot)

You could pivot this. I'd wait til the flight leaves, then ask at the ticket counter "Did I miss it? Oh noes! What is my option?" Hopefully it's ridiculous. If not, find a pretense why it won't work for you, "11:00!? I could drive there in that time!" and storm off angry. Now it's a customer service problem, not a hidden city cheat.

As long as you do not have checked luggage yes you can, I would still inform the airline though out of courtesy that you wont be using the last leg of the trip to save other travelers the hustle.

If you have checked luggage it gets a bit involved and you can probably still do it but you need the airline to help you so just ask them