Prior to the 3/3 Passenger Service System (PSS) switch, pre-merger United (aka PMUA, or sUA for subsidiary United Airlines) issued Type B travel credits for a variety of reasons, commonly when someone was Voluntarily Denied Boarding (VDB). Pre-merger Continental issued electronic travel certificates. The process for using Type B travel certificates has changed very little post 3/3. You can get a reservation put on hold over the phone or by going online and selecting a payment option of cash. You can mail in the certificates to United at (see https://pss.united.com/web/en-US/content/booking/flight/offerCode.aspx): United Airlines P.O. Box 1394 Houston, TX 77251-1394 Contrary to the text on the webpage linked above, it's also possible to get these reservations ticketed at the airport still, depending on the airport staff. So far, airports where at least one person has reported successful ticketing are: ALB, ATL, BOS, IAD, LAX, ONT, ORD, SAN, SFO. Airports where at least one person has reported being denied are: JFK, CLE. You should not be charged the airport ticketing fee. If you do decide to mail your travel certificates in, please note the text on the webpage. If it's within 14 days of travel, they'll charge you the full amount, then refund you when they receive the certificates. If it's outside of 14 days, they'll charge you the difference between the full amount and the amount on the certificates. Note that in the past, they would ticket reservations ordered by travel date, so someone sending in certificates for travel in May would probably be ticketed before someone sending in certificates for travel in September. As far as I can tell, all other rules regarding Type B certificates are still valid; I haven't tried booking a ticket including a non-United Airlines or non-United Express flight.