What is F/D OR FLT DIR on Boeing 737? (Flight Director)

The Flight Director (F/D), also known as the Flight Director System or simply FLT DIR, is an integral component of the Boeing 737 aircraft. It is a sophisticated guidance system that assists pilots in maintaining precise control over the aircraft during all phases of flight. The Flight Director provides the flight crew with command guidance for pitch, roll, and vertical navigation, enhancing situational awareness and reducing pilot workload.

Whether the aircraft is being manually flown or operating in autopilot mode, the Flight Director system continuously calculates and displays the optimal flight path for the aircraft. It assists the crew by providing visual cues on the Primary Flight Display (PFD), helping them to fly the aircraft accurately and efficiently.

How Does Flight Director Work?

The Flight Director on the Boeing 737 works by integrating various aircraft systems and sensors to generate accurate guidance cues for the pilots. It uses inputs from the Inertial Navigation System (INS), air data computers, Mode Control Panel (MCP), and autopilot system to calculate and display the desired flight path.

One of the primary functions of the Flight Director is to provide pitch guidance to the pilots. It indicates the required pitch attitude for the aircraft to follow the desired flight path. The Flight Director commands the pilot to raise or lower the aircraft’s nose to maintain the correct pitch angle. This ensures that the aircraft maintains the desired altitude and follows the planned vertical profile.

The Flight Director also provides roll guidance, indicating the desired bank angle to maintain the aircraft on the intended flight path. It helps the pilots to execute turns accurately and smoothly, ensuring that the aircraft tracks along the desired course.

Furthermore, the Flight Director offers vertical navigation guidance, assisting the pilots in following the correct vertical profile during climb and descent. It provides vertical speed targets and displays the desired rate of climb or descent. The pilots adjust the aircraft’s thrust and pitch accordingly to maintain the recommended vertical path.

The Flight Director’s guidance cues are presented on the PFD as command bars or V-bar markers. The command bars show the desired pitch and bank angles, while the V-bar markers provide vertical guidance. By following these cues, pilots can achieve precise control over the aircraft’s flight path.

Benefits of Flight Director on Boeing 737

The Flight Director system on the Boeing 737 offers several advantages to the flight crew, enhancing safety and operational efficiency. Some of the key benefits include:

1. Improved Situational Awareness: The Flight Director provides pilots with a clear and intuitive visual representation of the desired flight path. This improves their situational awareness, allowing them to make informed decisions and react promptly to changing conditions.

2. Reduced Workload: By providing precise guidance cues, the Flight Director reduces pilot workload, especially during critical phases of flight such as takeoff, approach, and landing. It allows pilots to focus on monitoring the aircraft’s performance and managing other tasks.

3. Enhanced Flight Performance: The Flight Director assists pilots in maintaining optimal flight parameters, ensuring that the aircraft operates within its performance limits. It helps in achieving smoother flights, reducing fuel consumption, and minimizing wear and tear on the aircraft.

4. Consistency and Standardization: The Flight Director system offers a standardized method of flying the aircraft, ensuring consistent performance across different flight crews. It helps maintain a high level of flight control and precision, irrespective of the pilot’s experience or skill level.

5. Enables Autopilot Functionality: The Flight Director is an integral part of the autopilot system on the Boeing 737. It provides guidance commands to the autopilot, enabling the aircraft to fly automatically along the desired path. This allows for efficient and reliable operations, especially during long-haul flights.


The Flight Director system, or FLT DIR, plays a crucial role in the operation of the Boeing 737 aircraft. It provides pilots with accurate guidance cues for pitch, roll, and vertical navigation, helping them maintain precise control over the aircraft. With its numerous benefits, the Flight Director enhances situational awareness, reduces pilot workload, and improves flight performance. It is a valuable tool that contributes to the safety and operational efficiency of the Boeing 737.

For More: What is SCM on Boeing 737? (Spoiler Control Module)