I cannot get a straight answer from United so I figured one of the travel experts here would be able to help me out....Just say I book a flight from London to NYC connecting thru Frankfurt. Now if I'm going to be in Germany around the date of the connecting flight, would I be able to just take that flight from Frankfurt to NYC without using the London-Frankfurt part. The reason I ask is because if I do end up being in Germany around that date, I do not want to have to book a flight to get back to London just so I can take a flight right back to Frankfurt en route to NYC if its not necessary. I'm hoping someone has either had experience with this or knows the answer so I can finalize my plans. Thanks in advance

Yes, it is possible.

You will be paying cancelllation fees and/or change fees depending on the fare rules of your purchased tix unless you have a full fare tix.

Okay, so even though I would be flying the same flight/route from Frankfurt-NYC, I would have to cancel the part of the route from London-Frankfurt and thus pay cancellation/route change fees? I was just hoping that if I let them know ahead of time, it would just be as if my flight started in Frankfurt instead of London--I figured it wouldn't be a problem and there wouldn't be any fees just because I would still be using the same number of award travel miles either way and I would also be opening up an additional seat for United for the London-Frankfurt flight (I'm sure theres more to it but that was my thought process). Just out of curiousity, would my ticket be cancelled as soon as I missed the flight out of Frankfurt? What would happen if I just tried to board in Frankfurt?

Yes.

You would not be allowed.

Airlines set their prices based on routes, not miles flown or anything like that.
LON-NYC is pried to compete with others in that market (e.g. undercutting BA, so that pax can get a better price if they are willing to suffer the inconvenience of backtracking) while FRA-NYC is another market altogether.

You can generally do this sort of thing at the close of your trip, skipping the last leg without penalty (though it is technically against the rules), but at the beginning, thet will just cancel you.

FWIW, there are some smaller airlines that might let you get away with it, but I certainly wouldn't try it with UA, LH or any other major international carrier.

And BTW - Welcome to FT!

The remaining of your reservations will be cancelled if you don't get on the first leg London-Frankfurt.

So, basically, the answer to your question is "NO", at least not the way you have in mind.

Certainly true on United... you HAVE to fly the first segment... or else all your downstream flights will be cancelled.

William