Frontier Airlines onward travel

Frontier Airlines checks your passport when you check in for an international flight, and won't let you board if your documentation isn't adequate.

How this airline usually checks

When you check in for an international Frontier flight, the airline asks to see your passport as proof of your citizenship and identity, which it describes as a legal requirement ("it's the law"). Frontier states plainly that if your documentation isn't adequate or sufficient, it can't allow you to board.^[1]

• Asks to see your passport at check-in for international flights
• Confirms it proves both your citizenship and your identity
• Can deny boarding if your documents aren't adequate or sufficient

When to be ready

Have your passport and any documents your destination requires ready at check-in, where a valid onward or return reservation covers the entry-requirement side of the check.

Routes where checks are more likely

• Matters most on Frontier's international routes, including flights to Mexico, Central America, and the Caribbean
• Applies at check-in on the day of departure rather than at booking

Sources

1. Frontier Airlines — International Travel

   “You'll need to present your passport providing proof of citizenship and identity when you check in for international flights — it's the law. ... If your documentation isn't adequate or sufficient, we simply can't allow you to board our aircraft.”