I am travelling from San Francisco to Kolkata via Frankfurt on a single return ticket at Kolkata. My United Air flight UA900 arrives at 9.45 AM and Lufthansa Flight LH750 for Kolkata departs at 10.30 AM. United flight as observed by me online arrives usually at Gates between C6 to C11 and Lufthansa Flight departs from gate B52... B58. I have no experience of travelling on International Flights. I have following questions in mind:

1. If my United flight arrives late then whome I should contact for rebooking, Food and hotel accmodation because next Lufthansa Flight departs from Frankfurt on alternate day?

2. How I can arrive at B hall from C hall faster any route guidance?

3. Will I need to go through another security check that takes long time to clear due to long line of passengers?

I will be thankfull to all those guide me properly.

Are you still in contact with the original agent

As you realize all this info can be found on the web

If your plane is running late, let the steward/ess know you have a connecting flight. Depending on how late you are running they might hold the plane for you (MIGHT!). If your flight is delayed at landing and it is the fault of the airline, typically they will book you on a later flight (if there is one) or put you up in a hotel for the night. This will only be at their expense if you miss your flight because THEY are running late - if you miss it because YOU don't get to the gate in time, it's not their problem. You can still contact any of the agents for the airline for rebooking and suggestions for hotels, etc. There might be fees for changing your flight, keep this in mind.

I haven't been to Frankfurt in years, and when I went I was staying and it was pre-9/11, so I don't know what the security guidelines are. You will probably have to go through customs when you land in Germany, but they might (MIGHT!) have a "continuing" area where you go right to the gates. If you have to go through customs you might also have to re-enter the gates terminal and go back through security - it all depends on the airport layout and their policies. I'm sorry, I just don't know for sure. If you used a travel agent when you booked this flight, contact him/her and ask. Either way, you might want to try and re-book your flight to allow more layover time. You are cutting it really close with only having 45 minutes. Even if you land on time and don't have go through customs, you still have to de-plane and get to the next terminal. De-planing alone can take 30mins depending on where on the plane you are sitting.