My main point is to get your boarding pass reprinted by UNITED before going through US security. I tried to use my boarding pass printed by LH in Munich when going through Newark security. A TSA agent looked at my boarding pass and told me to go through the Pre-Check line. When I finally got to the checkpoint, I was told the scanner could not read the ticket as Pre-Check. The same thing happened to another passenger. Standing AGAIN in another line was just too much. Without throwing a tantrum (which would not have helped), the agent took pity and had us taken to the head of the normal security check. Otherwise, the United flights (booked with miles) were just fine. I flew LOT to Warsaw on a new Boeing - super equipment. The Warsaw airport was terrific. Austrian Airlines was fine. Vienna's passport control was overwhelmed and with less than an hour between (on time) arrival and departure was VERY stressful. I DID make the connecting flight to Newark but ran to do it.