Which option is not a valid Aircraft Performance Category speed range?

• A. 91-120 kt
• B. 200-240 kt
• C. 121-140 kt
• D. 166-210 kt

Answer: (B)

Think about how speed ranges for Aircraft Performance Categories are defined: each airspeed should fall into exactly one category, with non-overlapping bands. In the given options, the range 166-210 kt already defines a high-speed category. A new range from 200-240 kt would overlap with that existing band for speeds between 200 and 210 kt. That overlap makes it impossible to assign a speed in that overlap to a single, unambiguous category, which is why this range isn’t a valid standalone performance category. The other ranges don’t overlap with the existing bands, so they can be used as distinct categories.