What is the maximum operating Mach number (Mmo)?

What is the maximum operating Mach number (Mmo)?

• A. 0.75
• B. 0.85
• C. 0.80
• D. 0.90

Answer: (C)

Mmo is the highest Mach number at which the airplane is approved to fly in normal operation, with enough margin to avoid buffet, loss of control effectiveness, and excessive structural loads. For this aircraft, the certified maximum operating Mach number is 0.80. This means you should not cruise faster than Mach 0.80 in normal flight, because higher speeds push into the transonic regime where buffet can occur and control/airframe performance can degrade. A speed like 0.85 or 0.90 would exceed the safe operating limit and isn’t permitted for normal cruise, while 0.75 is below the maximum, but not the upper limit.

Mmo is the highest Mach number at which the airplane is approved to fly in normal operation, with enough margin to avoid buffet, loss of control effectiveness, and excessive structural loads. For this aircraft, the certified maximum operating Mach number is 0.80. This means you should not cruise faster than Mach 0.80 in normal flight, because higher speeds push into the transonic regime where buffet can occur and control/airframe performance can degrade.

A speed like 0.85 or 0.90 would exceed the safe operating limit and isn’t permitted for normal cruise, while 0.75 is below the maximum, but not the upper limit.