Does anyone know what airline has the largest seat belts?
I know I would try a google search for a few answers to this.
All airlines have pretty much the same standard seatbelt sizes, as specified by Boeing or Airbus. But its not really the seatbelt size thats going to matter as much as the seat itself. I would recommend she try to upgrade to first class as the seats are much bigger than coach seats. It may be well worth the upgrade fee.
I've been in the industry a very long time, and they all have damn near the same seat belts! All of the plane manufacturers (Airbus / Boeing / Embraer..etc..) seem to contract them from one major supplier. Your aunt will have to use seatbelt extensions I'm afraid. There is nothing to be embarrassed about. I've seen people ask for two of them before. The embarrassing part would be if the flight attendant had to point out that she needed them in front of other passengers.