The
O-46A, the last of a long line of Douglas observation aircraft, was a victim of progress. It was designed to operate from established airfields behind fairly static battle lines as in
World War I. However, in 1939, a report was issued on the O-46A which stated that it was too slow and heavy to outrun and outmaneuver enemy fighter aircraft, too heavy to operate from small, wet, unprepared fields, and too large to conceal beneath trees. This report was a forecast of the future, for
World War II with its rapidly changing battle lines proved the need for light, maneuverable observation aircraft which could operate from unimproved airstrips. Consequently, in 1942, the "O" (observation) designation was changed to "L" (liaison). The O-46 was a development of the earlier
Douglas O-43. The 24th airframe of the O-43A contract was completed as the
XO-46 prototype, with a revised wing and an engine switch, from the O-43's
inline engine to a
radial engine, the
Pratt & Whitney R-1535-7. The Air Corps ordered 90 O-46As in 1935. They were built between May 1936 and April 1937. ==Operational history==