The "no-show rule" is a strict airline policy where failing to board the first segment of your flight itinerary results in the automatic cancellation of all remaining segments. In 2026, major carriers like Delta and United have tightened this rule; if you miss your outbound flight without notifying the airline before the scheduled departure, your return flight is voided, and your ticket value is often forfeited. This rule is designed to prevent "point-beyond" or "hidden city" ticketing where travelers book cheaper indirect flights but skip the final leg. If you miss your flight due to an emergency, you must call the airline immediately; under 2026 "Passenger Rights" updates, if the "no-show" was caused by a major irregular operation (like a massive storm), you are usually exempt from the penalty. However, for a standard missed alarm, the "no-show" rule means you essentially lose your seat and your money for the entire round-trip journey.