What is FMC on Boeing 737? (Flight Management Computer)

The Flight Management Computer (FMC) is a crucial component of the Boeing 737 aircraft’s avionics system. It plays a vital role in managing and controlling the aircraft’s navigation, flight planning, and performance optimization. As one of the most advanced computer systems on board, the FMC automates various tasks and calculations, making it easier for pilots to operate the aircraft efficiently and safely.

The Role of the Flight Management Computer

The Flight Management Computer is responsible for numerous critical functions during all phases of flight. Let’s explore some of its key roles:

1. Navigation and Route Planning

The FMC is the brain behind the aircraft’s navigation system. It receives information from various sensors, such as GPS, radio navigation aids, and inertial systems, to determine the aircraft’s position accurately. Based on this information, the FMC calculates the optimal route to the destination, taking into account factors like airways, waypoints, and airspace restrictions.

The flight crew enters the desired route into the FMC, and it generates a flight plan, also known as a lateral navigation plan. This plan includes the sequence of waypoints, altitude restrictions, and other navigation details required for the flight. The FMC continuously monitors the aircraft’s position during the flight and provides guidance to the autopilot or flight director to make precise course corrections and follow the planned route.

Moreover, the FMC also assists in managing enroute, arrival, and departure procedures. It can calculate optimized vertical profiles for climb and descent, taking into account factors like aircraft weight, winds, and speed restrictions. This ensures smoother and more efficient transitions between different altitude segments, minimizing fuel consumption and improving passenger comfort.

2. Performance Optimization

The Flight Management Computer helps optimize the aircraft’s performance by providing accurate data and calculations for various parameters. It takes into account factors such as aircraft weight, temperature, runway conditions, and wind effect to determine the most efficient takeoff and landing speeds. This information is crucial for pilots to achieve maximum performance and ensure the safe operation of the aircraft.

Furthermore, the FMC constantly monitors the aircraft’s fuel consumption and provides real-time updates to the flight crew. It calculates the expected fuel burn for the planned route, taking into account factors like winds aloft, aircraft weight, and altitude. This information allows the pilots to make informed decisions about fuel management, such as adjusting the flight plan to optimize fuel efficiency or calculating the minimum fuel required for a safe landing.

Additionally, the FMC assists in managing the aircraft’s engines and thrust settings. It calculates the required thrust for various flight phases, such as climb, cruise, and descent, to optimize fuel consumption and reduce engine wear. Based on this information, the flight crew can adjust the thrust levers to maintain the desired performance parameters.

3. Systems Integration and Automation

The Flight Management Computer plays a crucial role in integrating various aircraft systems and automating numerous flight tasks. It receives inputs from other avionics systems, such as the autopilot, autothrottle, flight controls, and engine instruments, and uses this information to make accurate calculations and decisions.

For example, during an automatic approach and landing, the FMC works in conjunction with the autopilot and autothrottle to guide the aircraft along the instrument approach procedure. It calculates the required vertical and lateral navigation paths, takes into account factors like glide slope and localizer deviations, and provides precise guidance to the autopilot and autothrottle to maintain the desired approach profile.

Moreover, the FMC enables advanced functionality like Required Navigation Performance (RNP) and Performance-based Navigation (PBN). These features allow the aircraft to fly precise trajectories based on satellite navigation and advanced onboard performance monitoring. The FMC uses this information to optimize the flight path, saving time, fuel, and reducing emissions.


The Flight Management Computer is a vital component of the Boeing 737 aircraft, providing essential functionality for navigation, flight planning, and performance optimization. It automates numerous tasks and calculations, allowing pilots to operate the aircraft more efficiently and safely. Whether it’s planning the optimal route, optimizing fuel consumption, or integrating various aircraft systems, the FMC plays a central role in ensuring a smooth and successful flight.

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