How can I modify a United Airlines flight? Anyone could become a victim: After making a reservation for a United ticket, a situation arises that necessitates changing it a few days, weeks, or even months later. You'll need to be aware of the united united airlines flight change in such situation so you can decide what to do next. Tickets for domestic trips (including those to Puerto Rico and the US Virgin Islands) as well as international trips (to Mexico or the Caribbean) on United Airlines are subject to change. No change costs are incurred for the economy. Additionally, in addition to admissions, changes to your flight's timing, date, or destination can be done online or over the phone.