Time needed to change planes
 

We are flying from Charlotte to Dulles on United 3397 on 1/12/15 arriving at 4:05 pm then we are flying United 936 from Dulles to Zurich leaving at 5:45 pm. Do we have enough time to make our connection? Will United check our bags thru to Zurich in Charlotte since we are flying the same airline?

Shouldn't be a problem even if the first segment is a bit late. Bags will be checked through to your final destination. Arriving and departing flights at Dulles are likely to be in different concourses, but just follow the signs. And there are no security checks involved at Dulles with your connection.

And welcome to flyertalk.

Thank U. I feel a little more at ease.

You should feel a lot more at ease. UA absolutely will check your bags through to ZRH and if your inbound and outbound gates are as far apart as they could be and you have just missed your inter-concourse train / moon buggy. it will take 20 minutes. UA requires you to be at your departure gate by T-30 for international, so that gives you a minimum of 50 minutes of flex (20 minutes to the UA gate and 30 minutes prior to scheduled departure).

Furthermore the 30 minute rule is just the official rule; obviously not when they close the doors. I board usually 15-20 min before departure on an intl flight. They are not going to require delayed connecting passenger to be there at T-30 min. It just gives UA a disclaimer if they decide to close the door early and ensures that most people get there well ahead of time.

It is not just to give them a way out if they close the flight early, it is also for possible oversale situations. When that happens, UA offloads the misconnects at the dot of T-30. Needless to say, the misconnects are reacommodated, but no IDB payment and no IDB black mark with DOT.

It's fine to board latish in the process so long as you are around, but it's a risk to schedule a connection. ZRH only has one service/day. While there are alternatives, they are less convenient.