What is the MMO value?

What is the MMO value?

• A. .78
• B. .82
• C. .84
• D. .90

Answer: (B)

MMO is the maximum operating Mach number, the speed limit the airplane must not exceed at high altitude to stay within certified structural and control limits. For the ERJ 175 used by SkyWest, the published MMO is Mach 0.82, meaning in cruise you should not exceed this Mach number. This value is set because above it the aircraft could experience adverse aerodynamic effects or exceed certification limits, even as indicated airspeed rises with altitude. The other options are outside the safe certification envelope for this airplane: a Mach 0.78 would unnecessarily restrict operations, Mach 0.84 would exceed the certified limit, and Mach 0.90 would be well beyond what the aircraft is designed to handle. Therefore, Mach 0.82 is the correct MMO value.

MMO is the maximum operating Mach number, the speed limit the airplane must not exceed at high altitude to stay within certified structural and control limits. For the ERJ 175 used by SkyWest, the published MMO is Mach 0.82, meaning in cruise you should not exceed this Mach number. This value is set because above it the aircraft could experience adverse aerodynamic effects or exceed certification limits, even as indicated airspeed rises with altitude. The other options are outside the safe certification envelope for this airplane: a Mach 0.78 would unnecessarily restrict operations, Mach 0.84 would exceed the certified limit, and Mach 0.90 would be well beyond what the aircraft is designed to handle. Therefore, Mach 0.82 is the correct MMO value.