When you book a flight ticket of United Airlines, you can complete your purchase by making the payment through one of the following forms: American Express Alipay Chase Pay JCB Diners Club International MasterCard PayPal Credit (for the USA billing addresses only) PayPal Discover Visa Uplift UnionPay (only for the selected regions) UATP Cash Payment (available at the United ticketing office or airport ticket counters only)