One of the collateral benefits to the carriers which has come out of the current situation, is their ability to discover "irregularities" as a result of heavy scrutiny. These include, flying on someone else's ticket, using another person's club card, hidden cities and other fare games, just to mention a few. Short answer....don't no show a segment. They will proably notice. On the other hand, I was in Philly a few weeks ago. I normally terminate at White Plains, but sometimes will use New Haven if the fare is better. I travel so often, I just forgot to look at the ticket. I thought I was going to White Plains, but it was actually New Haven. By the time I showed up for the HPN flight, the New Haven one had already left. It was no big deal, and they just put me on that one. I did, however, have a checked bag (unusual for me), and I immediately asked the lead agent if no showing had complicated things (like maybe my bag was impounded). She said not to worry. Seems they only match tags on the intitial leg, presumably figuring that if it got there within the system it is OK. Anyway, it was in New Haven, and had gone on the flight I didn't take. Even so, I don't recommend no showing a segment in these times, but the security issues continue to be somewhat murky. Of course, it was USAirways Express, and it was Philly.