US TSA etc.
The two previous replies are quite correct, the TSA approval is mandatory before flight training or simulator can be commenced. There is a TSA enrollment procedure where they want to know everything about you and more...then you have to get yourself fingerprinted at an accepted location etc etc....have a look on the TSA website. I went through all this a few weeks ago, it's quite tiresome but if you need help the TSA people are very helpful. The other thing is that from the 12th.Jan, in a couple of days in fact, there is a new immigration procedure supposedly coming into force, so best to check on that as well...good luck!