I'd suggest putting your pin in checked luggage and finding a temporary substitute to wear during the flight...I have a nice big White Sox button that looks great on the kilt and that seems to elicit smiles from just about everybody...except Cubs fans...or Angels fans...or....

Take Bubba's comment about the average screener as the truth...it seems like most of the folks doing this aren't all that perceptive and they treat anything longer than it is wide as a security threat.

My pin is a sword with a targe that has the Horses of Inverurie on it...I do have a larger version of the targe made by the same jeweler that will work as a round kilt pin when the need arises...I guess having an auxilliary pin that's round is the best bet...otherwise you'll be mailing your kilt pin back to yourself from the airport.

Best

AA