The Potez 637 A3 was a three-seat reconnaissance aircraft that served in small numbers with the Armée de l'Air during the Battle of France, but that was already being phased out in favour of the Potez 63.11.
The Potez 63 family of aircraft were developed in response to a French Air Force specification issued in October 1934, calling for a twin-engined two or three seat multipurpose fighter, capable of acting as a day fighter, night fighter or fighter director aircraft. The first two members of the family, the Potez 630 and Potez 631 were developed in parallel, and were virtually identical low-winged twin-engined monoplanes, with a close resemblance to the Messerschmitt Bf 110. After trials with the two prototypes ten evaluation aircraft were ordered, including one Potez 637 A3 reconnaissance aircraft. The Potez 637 was similar to the Gnome-Rhone powered Potez 631, but with a glazed gondola underneath the fuselage, designed to take a prone observer, and with the 20mm cannon in the nose replaced with a single machine gun.
An order for sixty Potez 637s was placed in August 1938. The new aircraft was to replace the Potez 542, which was serving in four reconnaissance groups (Groupes de Reconnaissance, or G.R.). This order was placed some time before the prototype made its maiden flight, which came in October 1938.
The Potez 637 began to enter service in May 1939, and was used to equip two reconnaissance Escadres - the 33rd and 52nd. At the start of the Second World War fifty three aircraft were in front line service, all with these two units. After the outbreak of war the Bloch 131, Potez 637 and a number of older Mureaux types were used on deep reconnaissance missions over Germany, but losses were so high that after September only the Potez was allowed to cross the border.
By May 1940 none of the reconnaissance groups only used the Potez 637. GR I/33, II/33, II/36 and I/52 were using the biggest mix of aircraft, with Potez 637s, Potez 63.11s and the more modern Bloch 174, while GR II/52 and I/36 operated both Potez types. The Potez 637 was in the process of being withdrawn from frontline service at the start of the German offensive.
The Potez 637 units suffered heavy losses during the short campaign in the west. G.R. II/52 lost all of its aircraft in sixteen days while G.R. II/33 lost all seven of its Potez 637s. As with the Potez 63.11, the main enemy was flak, both the very heavy German anti-aircraft fire, and Allied guns firing on what they believed were Bf 110s. German fighters were less effective, and the Potez 637 was often able to outmanoeuvre the Bf 109.
At the end of the Battle of France only twelve Potez 637s remained intact in France. Six remained by 1 November, and none one year later. The reconnaissance units of the Vichy Air Force used either the Potez 63.11 or the Martin 167F.
Engine: Gnome & Rhone 14 M4/M5 or M6/M7 engines
Power: 570hp at sea level, 660hp at 16,400ft, 700hp at take-off
Wing span: 52ft 6in
Length: 36ft 4in
Height: 11ft 10 1/2in
Normal Loaded Weight: 9,314lb
Max Speed: 270mph
Cruising Speed: 198mph
Range: 963 miles
Armament: Three 7.5mm machine guns: one fixed forward firing, one fixed rear firing, one flexibly mounted rear firing