Phi Doan VNAF Observation Squadron This cover was sent from KBC 4652, which served the Vietnamese Air Force (VNAF) 4th Air Division. "Phi Doan 122" in the return address identifies the 122d Observation Squadron based in Bien Thuy. This Squadron flew O-1 and U-17 aircraft on its missions. < Back < Imnaha Stamps Home Original content ©2008 Andrew Crenshaw - All Rights Reserved.