Many travelers assume it’s fine to check in a few hours before a flight, maybe even while en route to the airport. But that assumption can be costly.

Weeks ago, I paid Lufthansa £185 for a return flight from London Heathrow to Munich. The fare is non-refundable. But with 30 hours before my flight home, I am obliged to go online to declare that, yes ...

NEW YORK — Stragglers beware: U.S. travelers flying with United Airlines will have to check in to domestic flights a little earlier starting next week. That is, if they’re customers only taking ...

Delta Air Lines is advising passengers with checked bags to arrive even earlier than usual at the airport by introducing a significant change to its baggage check-in policy for domestic flights, ...