Another example was the replacement of a convergent with a C-D nozzle on the YF-106/P&W J75 when it would not quite reach Mn=2. Together with the introduction of the C-D nozzle, the inlet was redesigned. The USAF subsequently set a world's speed record with the F-106 of 1526 mph (Mn=2.43).[25] Basically, a divergent section should be added whenever flow is choked whithin the convergent section.