United Airlines allows travelers to upgrade their seats to the next higher cabin class. However, the upgrade is only given when there is a seat available on the flight. Moreover, there are several ways to make a United Airlines Seat Upgrade. Passengers can upgrade their flights directly by visiting the official United Airlines website and using one of two methods, including purchasing the upgrade or using their miles. For more details related to the upgrade, contact the customer service of United Airlines or follow the link to the blog.