Flying standby is a great way for you to get preferable flights or to fly cheaper. What is cool about standby is that you can save money while adding excitement to your travel experience. However, before you jump into a standby adventure, there are a number of things you should know. In the United, customers holding restricted Footnote tickets can make same-day flight changes for a discounted fee. The itinerary must be operated by United or United Express, and the ticket number must begin with 016. The same-day flight change option will be available within 24 hours before your originally scheduled flight. The requested flight must be departing within 24 hours from the time the request is made. Same-day flight changes may be confirmed when checking in online, at any airport kiosk, by calling your local United Customer Contact Center or with a united representative.