<p>I’ve seen baggage measured for international flights, but domestically I’ve only ever seen it weighed.</p>
<p>My son’s tenor sax exceeds carry-on dimensions. But it’s an expensive instrument, and we prefer not to check it or mail it. I’ve had good luck emailing with Jet Blue service and getting special permission for carry-on (and if no room, it would get gate-checked with the baby carriages).</p>
<p>Thanks everyone for your responses. Since no one on this thread has reported actually getting their bags measured (at least in the US) I have decided to take the calculated risk and go with the duffel I ordered and keep it below 50 lbs. I will bring some extra straps, great idea MWmom. I will resurrect this thread in Sept sometime after the trip has been made and update it with my results. Thanks everyone!</p>