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Boeing 247D DZ203 c/n 1726 ex NC13344, CF-TBA and RCAF 7655. This famous aircraft, one of eight bought the British Purchasing Commission for Canada, was used to develop the ILS system, as well as airborne intercept radar. Per Phil Butler's 'Air Arsenal north America': "One of the Canadian purchases was later shipped to England (in July) 1941 where it was sued for early airborne radar experiments. The fuselage was capacious enough to house the bulky experimental radar sets and the Boeing was used to develop Airborne Interception (AI) radar for use in night fighters. Later it was used for the development of Instrument Landing Systems until being scrapped some time after the end of the war. This was c/n 1726 ex NC13344, CF-TBA and RCAF 7655 before becoming DZ203 with the TRE at Defford. It was was finally scrapped in August 1947 at No 34 MU, Sleap, reportedly after being damaged in its hangar at Defford during winter storms in late in 1946." There is a book written about DZ203 which I have on order, but it is shipping from the UK and has not yet arrived. "Top Secret Boeing" by Bob Shaw.

Boeing 247

I believe this is NX13365 used by United as a Flying Research Lab. The covered direction finding loop was unusual at this time. Stig

Here's Pathe newsreel footage of NX13365 (c/n 1858) flying over Manhattan, as Stig noted, while operating as United Air Lines' Flying Research Lab. This aircraft also was the last Boeing 247 (Boeing 247-D) built. YouTube: British Pathé - "New American Plane (1938)"