Yes, you can buy a flight on the same day of departure, but it is no longer the "budget-friendly" option it once was. These are often referred to as "Walk-up Fares." While you can technically buy a ticket at the airport ticket counter, it is almost always cheaper and faster to book via the airline's mobile app or a site like Skyscanner even while standing in the terminal. In 2026, same-day tickets for domestic flights are usually $200--$500 more expensive than those booked weeks in advance, as airlines capitalize on business travelers or emergency flyers. For international routes, same-day booking can trigger additional security scrutiny, such as the "SSSS" (Secondary Security Screening Selection) on your boarding pass. Most airlines allow online bookings up to 2 to 3 hours before the scheduled departure; after that, you must visit the physical airport counter to see if any "standby" or last-minute seats remain available.