- "changeable airline ticket"
"changeable" 「変更可能な」
"airline ticket" 「飛行機チケット」"boarding pass" も言えます。
- "flexible ticket"
"flexible" 「柔軟」・「変更可能」
"Once you know when you will receive visa, book your flight to Japan. We recommended that you book a ticket that can be changed in case the visa is not issued on time or entry restrictions are imposed."
"a ticket that can be changed" 「変更可能な飛行機のチケット」