While the Chase Travel portal (powered by Expedia) is highly comprehensive, it does not show every airline in the world. The most notable omission for U.S. travelers is Southwest Airlines, which famously does not list its flights on third-party booking sites to keep costs down and maintain direct customer relationships. You generally have to call the Chase Travel center to book Southwest flights with points. Additionally, many ultra-low-cost carriers (ULCCs) like Allegiant Air or smaller regional airlines in Asia and Africa may be missing from the search results. Chase also might not show specific "basic economy" or "special promotional" fares that are exclusive to an airline's own website. For a savvy traveler, this means that while Chase is a great place to redeem "Ultimate Rewards" points for a 25% to 50% bonus (depending on your card), it should not be your only search tool. It is always best to cross-reference with a site like Google Flights or the airline's direct page to ensure you are seeing the full range of schedule options and the absolute lowest price before committing your points or cash within the Chase ecosystem.