Originally Posted by
minhaoxue
UA now parks their regional flights in T1.T1 is not connected to T3 and you cannot walk between the Terminals post security. There is however, a shuttle bus run by UA between the Terminals. in T1, you pick it up between gates 37/38, lower level. They will drive you airside over to T3 and drop you off near gate 72. Then , continue airside past Gate 75 through the sterile walkway to International Pier G for SQ departure. This will alleviate going through security.
There is also a shuttle that goes directly to the International terminal.
1 hour is just enough to do this if everything goes well. If anything at all going wrong, you've got almost no chance of making it.