In 2026, the short answer is no, unless you have a very flexible "Full Flex" ticket. Most standard airline "Conditions of Carriage" state that if you miss the first leg of a journey (the "outbound" flight), the airline's system will automatically cancel all remaining segments, including your return trip. This is a measure to prevent "throwaway ticketing." If you realize you cannot make your first flight but still intend to take the return, you must call the airline immediately before the first flight departs to see if they can re-book you or "save" the return leg; however, this usually incurs a significant change fee and a fare difference. By 2026, some consumer protection laws in Europe have challenged this "no-show" rule, but for most global carriers, missing the first flight without prior notification remains an expensive mistake that results in a voided ticket and a total loss of your travel funds.