Whether you have to check a double stroller depends primarily on its size and the specific airline's policy, but most must be gate-checked or checked at the counter. Standard double strollers are typically too large and heavy to fit in an airplane's overhead bin. Most major airlines allow you to use the stroller through the airport and "gate-check" it for free just before you step onto the plane; it is then stored in the cargo hold and returned to you at the jet bridge upon landing. However, some ultra-compact double strollers (like certain side-by-side "umbrella" models) that fold down to roughly 56 x 36 x 23 cm may be permitted as carry-on luggage if they meet the airline's weight and dimension limits. If your double stroller is exceptionally bulky, non-collapsible, or weighs over 20kg, the airline may require you to check it at the ticket counter as oversized luggage. Always verify with your carrier, as budget airlines often have stricter "one-piece" rules for infant gear compared to full-service legacy carriers.