 In July 1940, Schmid grossly overestimated the strengths of the "Luftwaffe" and underestimated the RAF.The most serious mistakes were made concerning radar, airfield identification, and production sites.Schmid asserted that the number of operational airfields in southern England were severely limited; estimated that the British could produce only 180–330 fighters per month (the true figure was 496) and that figure would decrease, indicating that the RAF could not sustain a long battle of attrition.