While the "2-hour rule" is a standard industry recommendation, it is not always a legal or technical requirement for every flight. In 2026, most airlines allow (and encourage) digital check-in via their app up to 24 hours in advance. If you have checked in online and have no checked baggage, you can often arrive at the airport 60 to 90 minutes before a domestic flight and still comfortably make your gate. However, the 2-hour window is critical if you are checking bags, as most airlines have a strict "bag drop cutoff" 45 to 60 minutes before departure. For international flights, the 3-hour rule is still strongly advised due to additional document checks (passports/visas) and longer security and immigration queues. In 2026, many busy airports like LHR or JFK use biometric gates, but they can still be overwhelmed during peak hours, making that 2-hour buffer a necessary safety net against missing your flight.