12/31/2010. The five 307s built for TWA (c/n 1998 to 2002, registered NC19905 to NC19909) were designated SA-307B and differed sufficiently from the four Pan American Airways 307s in detail to warrant the new Aircraft Type Certificate 726. Externally, the most noticeable feature was the triangular external wing flap hinges.

Considerable confusion exists as to the registration numbers of the SA-307Bs because of the wide circulation of photographs by Boeing and the airline showing the second TWA aircraft (Fleet Number 401) with the registration NX1940, as shown above. The actual registration of this aircraft was NX19906 (later NC). The figure 6 was deleted and the second 9 changed to a 4 after the aircraft had flown briefly. This altered number was used temporarily to publicize 'The 1940 Airliner' when it was flown on a pre-service tour of TWA's routes. The original registration was restored after the tour.

In 1942 TWA's 307s were drafted by the USAAF Air Transport Command. They were assigned the military designation of C-75, and the civil registrations were cancelled and replaced by the USAAF serial numbers 42-88623 to
42-88627. Although military property and used for military business, the 307s were operated by TWA crews until they were sent to the factory in 1944 for reconditioning prior to return to the airlines as SA-307B-1. External differences were deletion of the external flap hinges and installation of a larger B-17G horizontal tail located 3 ft (0.91 m) further aft.

After its C-75 life under the USAAF serial 42-88623, the pictured aircraft was reregistered NC19906. Together with the other four SA-307B-1's it was sold to the French airline Aigle Azur in 1951, and became F-BELU. Thereafter it went to Air Laos in 1952, to Airnautic in November 1959, to CITCA in 1965, and registered as XW-TFP to Cambodia Air Commercial in 1974. It was written off in a forced landing in Mekong River in 1975. View also photo 10264.