knit-in ,
While doing something like this violates the airline rules and your contract of carriage, it is not illegal. E.g. it is a civil matter between you and the airline, and criminal charges would not be brought. Further, I'm not sure the courts always go with the airlines interpretation of the contract.

On a more practical note, indeed, your reservation would cancel because of the no show. If the gate agent was either very busy or sympathetic, they might let you on. You all know how crazy airports can be, and they simply don't have time to spend ten minutes sifting through the history of your pnr to figure out what happened, they just have to get that flight off the gate five minutes ago or its really going to screw up the schedule for the rest of the day.

On the other hand, you might hit a quiet gate, and a gate agent who is intent on sifting through your record for forty five minutes to figure out exactly what happened, and how exactly you are where you are with your reservation showing like it is.

It is a gamble indeed not without risk or not for the faint of heart.

I would not call CO reservations but instead try to get an airport agent to fix your record so the segments not flown are cancelled. Like maybe you would say you had a connection in IAH where you want to start out, etc. So the next time you are flying, if you see an agent you think is nice, see if they will do it for you. Only trouble is you would have had to buy the ticket. You won't just be able to go up to the counter, and say oh yah I want to buy this hidden city fare.

CozmelJean, in a situation like you had, you MUST call CO and get tham to manually keep the computer from cancilling you flights. I have this happen often.
Jetsetter, I disagree with you advice. Busy or not CO checks every ticket against the manafest on EVERY flight. This is part of the process of closing every flight. After the first segment isn't flown the computer will be notified within about 1/2 an hour. You seat will then be given up all future flights AND reassigned. Thus it's likey even if you got on the second (and subsiquent flights) somebody is likey to have the same seat assignment. This will be a huge clue to the FA. And you will get caught.

Thanks Cigarman, I will keep this in mind. It was a bad situation since I had to get a much later flight than I had planned and this flight, (though I was ASSURED by the gate agent would get into New York by 11:30, she meant, the NEXT DAY! I would have missed work!) I luckily was able to get on a later flight back to Newark though, as it would not get in until 3 am and I had left my car at LGA from my departure (cabbed to EWR), I couldn't get home, had to call friends in NJ asked them to leave a key for me, then had to wear Mexican vacation clothes to work the next day!) ANYWAY thanks and, analise unfortunately I can't recall whether I paid more or not, I was so upset!

Cigarman,
I know as well for sure the computer will cancel out the downline space. What I was referring too was when the pax checks in, and the res is cancelled, the gate agent **might** reenstate the space on the cancelled flights (e.g. rebook and then check in the pax). I have not used hidden cities myself, and even though I am always very observant of the conversations at the gate, I can not remember a single time where I heard a gate agent acusing a pax of doing a hidden city like thing though I'm sure it has happened. Well, I guess this is similar to a hidden city e.g. getting on in the middle of the itin. If anyone tries this at home, I would also strongly suggest using paper tickets. CO's e-ticket system seems to have a lot of lengthy computer entries that agents must put in to get your ticket back in sync when changes are made. Have you ever watched agents and all they have to enter in the computer even for simple changes like say a missed connection rebooked, etc?

jimbob, you would be taking a huge risk to try to get on at the second segment. Since the fare difference is $200~, just buy a RT IAH-EWR to tack on before and after the EWR-IAH-NRT-IAH-EWR flights. Then you get more miles!