Issued in 1920, the carmine, 5s(on 6s)+5s tiger's head "Scout's Fund" Type I overprint on Siam's first contract air mail flight from Nagor Rajasima to Udorn.  Posted in Bangkok on August 22, 1931 at 10:00pm, the cover traveled by night express train to Korat's (now Khorat) airfield Nagor Rajasima (now Nakhom Ratchasima).  After receiving the rectangular cachet "First Flight, Air Mail by the Aerial Transport Co. of Siam, Ltd., Korat and Udon, August 24, 1931", it flew on the morning of August 24 to Udorn where it received an Uttara Dhani receiver.