What is MMO on Boeing 737? (Maximum Mach Operating Speed)

When it comes to commercial aviation, safety and performance are of utmost importance. Aircraft manufacturers like Boeing invest significant time and resources to ensure their airplanes meet stringent operational standards. One crucial parameter to consider is the Maximum Mach Operating Speed, abbreviated as MMO. In this article, we will explore what MMO is, its significance for the Boeing 737 aircraft, and how it influences the overall flight operations.

MMO is the highest Mach number that an aircraft is allowed to achieve in flight. The Mach number, named after Austrian physicist and philosopher Ernst Mach, is a dimensionless quantity that represents the ratio of an aircraft’s true airspeed to the speed of sound in the surrounding air. The speed of sound varies with temperature and altitude, but it is typically around 768 miles per hour (1,236 kilometers per hour) at sea level and 59 degrees Fahrenheit (15 degrees Celsius).

The Boeing 737, a widely used narrow-body aircraft, has a specific MMO value that pilots must adhere to during operations. This value ensures the aircraft operates within safe limits and prevents any structural or aerodynamic issues that could compromise the flight.

Why is Maximum Mach Operating Speed Important?

The Maximum Mach Operating Speed is a critical parameter for understanding and optimizing an aircraft’s performance. It plays a crucial role in determining various operational aspects, including fuel efficiency, engine performance, aircraft stability, and the overall safety of flights.

Operating an aircraft too close to or surpassing its MMO can lead to several undesirable consequences. Firstly, it may exceed the structural limits of the airframe, potentially causing damage or even catastrophic failure. Excessive speeds can put excess stress on the wings, fuselage, and other components, leading to potential structural integrity issues.

Additionally, operating at or beyond MMO can negatively affect the aerodynamic stability of an aircraft. At high speeds, the airflow over the wings can become turbulent, reducing lift and increasing drag. This turbulence can also create control issues for the pilots, making it more challenging to control the aircraft accurately.

Moreover, exceeding the MMO can drastically impact an aircraft’s fuel efficiency. As the aircraft nears or exceeds the speed of sound, the resistance faced by the airplane increases significantly, resulting in higher fuel consumption. This increased fuel burn negatively affects the aircraft’s range and operational costs.

The Maximum Mach Operating Speed on Boeing 737

The specific Maximum Mach Operating Speed for a Boeing 737 depends on its variant. Each variant has slightly different aerodynamic characteristics and operational limitations. It is crucial for pilots to understand these limitations to ensure a safe and efficient flight.

For example, let’s consider the Boeing 737-800 variant, one of the most common models in operation. The MMO for this aircraft is Mach 0.82, which translates to approximately 581 miles per hour (935 kilometers per hour) at cruising altitude. This speed provides a balance between fuel efficiency and performance, allowing the aircraft to operate optimally within its operational envelope.

It’s important to note that the MMO specified by the aircraft manufacturer is a redline speed, beyond which pilots should not operate the airplane under normal circumstances. However, there can be specific situations, such as severe turbulence or wind shear, where exceeding the MMO momentarily may be unavoidable for the safety of the aircraft and passengers. In such cases, pilots are trained to handle these situations and ensure a smooth and safe flight.

To maintain the Maximum Mach Operating Speed within the prescribed limits, the Boeing 737 and other aircraft are equipped with various speed control systems and instruments. These systems include air data computers, Mach trim controls, and other indicators that provide crucial information to the pilots and enable them to monitor and adjust their speed accordingly.


The Maximum Mach Operating Speed, MMO, is a crucial parameter that ensures the safe and efficient operation of the Boeing 737 aircraft. Adhering to the specified MMO helps prevent structural damage, maintain aerodynamic stability, and optimize fuel efficiency. Pilots play a vital role in monitoring and controlling the aircraft’s speed within the prescribed limits, using various onboard instruments and their training. By understanding and respecting the MMO, pilots can ensure a smooth and safe travel experience for passengers on the Boeing 737.

For more detailed technical specifications and information about the Boeing 737, you can visit Boeing’s official website.

For More: What is F/E on Boeing 737? (Flight Engineer)