Yes, unaccompanied minors board first on United Airlines. Furthermore, United Airlines has been categorized into six different boarding groups, including Pre-boarding. Additionally, a United Airlines Unaccompanied Minor is included in the Pre-boarding groups, and they are the first ones to get into the flight. In order to get into the flight first, a minor has to arrive within the minimum check-in period, or else they could be the last one to get onto the flight.