I have Global Entry so I have never used Mobile Passport. A friend of mine leaves for Germany in a couple of days and is setting up Mobile Passport.
She is on a KLM flight operated by Delta. On Mobile Passport, under airline, which does she use--KLM or Delta?
Don't quote me, because I'm just guessing, but I do use Mobile Passport regularly. I just enter the airline and flight number that are on my boarding pass or ticket. I can't imagine it makes any difference.
Enter what’s on the plane tail. But either will probably work.
Use the Delta flight number.
It only works on the return flight, so whatever's on the plane coming back -- you can change it on the fly. It doesn't get transmitted until the traveler activates it at the port of U.S. entry. Tell her to make sure her phone has connected to wifi at that airport and has automatically changed to local time BEFORE she hits the button.
