aerodynamicsFAA-published sample question (ATM, Aug 2021)
When piloting a turbojet transport airplane, what is a possible result when operating at speeds 5-10 percent above the critical Mach number?
A
Increased aerodynamic efficiency.
B
Decreased control surface effectiveness.✓ Correct Answer
C
Occasional low speed Mach buffet warnings.
Explanation
Above critical Mach number, shock waves form on the wing and can cause flow separation over the control surfaces, reducing their effectiveness, along with high-speed buffet and possible Mach tuck (Airplane Flying Handbook Chapter 15). Efficiency decreases, and the buffet encountered is high-speed, not low-speed.
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