What is FPA on Boeing 737? (Flight Path Angle)

The Flight Path Angle (FPA) is a critical parameter in the aviation industry, especially when it comes to aircraft like the Boeing 737. It plays a crucial role in determining the trajectory and the vertical path of the aircraft during flight. In simple terms, the Flight Path Angle represents the angle between the aircraft’s flight path and the horizontal plane. Understanding and controlling the Flight Path Angle is essential for pilots to execute smooth takeoffs, landings, and navigate through various flight phases.

Let’s delve deeper into the concept of Flight Path Angle and explore its significance on the Boeing 737.

The Importance of Flight Path Angle on Boeing 737

The Flight Path Angle is a fundamental parameter for a Boeing 737 pilot. It provides critical information about the vertical motion of the aircraft, allowing the pilot to maintain the desired altitude or initiate climbs and descents as required. The Flight Path Angle is closely related to the pitch angle of the aircraft, which represents the angle between the longitudinal axis of the aircraft and the horizontal plane.

While the pitch angle primarily controls the aircraft’s vertical motion, the Flight Path Angle takes into account the impact of horizontal speed and allows for a more comprehensive understanding of the aircraft’s path through the air. By adjusting the Flight Path Angle, pilots can control the rate of climb or descent and ensure smooth transitions between different altitudes during the flight.

During takeoff, for example, the pilot must establish a positive Flight Path Angle to initiate the climb and gain altitude. The Flight Path Angle also plays a crucial role during the approach and landing phase, as the pilot needs to control the descent rate and ensure a safe touchdown on the runway.

Managing the Flight Path Angle requires a thorough understanding of several factors, such as airspeed, thrust, and aircraft configuration. Pilots rely on the Boeing 737’s Flight Management System (FMS) and Autopilot system to accurately control the Flight Path Angle and maintain precise flight profiles.

Controlling Flight Path Angle on Boeing 737

The Boeing 737 incorporates advanced flight control systems that assist pilots in controlling the aircraft’s Flight Path Angle. The Autopilot system allows for automated control of the aircraft’s trajectory, including the Flight Path Angle, during different phases of flight.

To control the Flight Path Angle manually, pilots use various inputs such as the control column, throttle levers, and the Flight Control System. By adjusting the elevator controls, pilots can modify the aircraft’s pitch and subsequently the Flight Path Angle. Additionally, changes in thrust and configuration influence the aircraft’s vertical performance and, consequently, the Flight Path Angle.

During landing, for instance, the pilot gradually reduces the thrust while adjusting the control column to maintain a specific Flight Path Angle and descent rate. The FMS assists by providing guidance and reference values, helping pilots achieve the desired Flight Path Angle with precision.

It’s important to note that the Flight Path Angle can be affected by various external factors, such as wind conditions, aircraft weight, and altitude. Pilots must continually monitor and adjust their inputs to maintain the desired Flight Path Angle and ensure a safe and efficient flight.

The Role of Flight Path Angle in Energy Management

Flight Path Angle plays a significant role in energy management during a Boeing 737 flight. By controlling the Flight Path Angle and managing the aircraft’s vertical motion, pilots can optimize fuel efficiency and overall performance.

During the climb phase, for example, pilots aim to maintain a specific Flight Path Angle to achieve the most efficient climb rate for a given airspeed. This allows them to minimize fuel consumption while still ascending at a desirable rate. Similarly, during descent, a controlled Flight Path Angle enables pilots to manage the aircraft’s energy and plan for a smooth approach and landing.

In addition, understanding and utilizing the Flight Path Angle helps pilots in calculating the most efficient descent path, reducing noise pollution near airports, and adhering to specific noise abatement procedures.

By optimizing the Flight Path Angle, pilots can significantly contribute to fuel savings and reduce environmental impact, ensuring a more eco-friendly operation of the Boeing 737 aircraft.


In conclusion, the Flight Path Angle (FPA) is a critical parameter in aviation, particularly for aircraft like the Boeing 737. Pilots rely on the Flight Path Angle to control the aircraft’s vertical motion, facilitate smooth takeoffs and landings, and execute precise transitions between different altitudes.

Controlling the Flight Path Angle on the Boeing 737 involves utilizing advanced flight control systems, adjusting inputs such as thrust and configuration, and continuously monitoring external factors. By effectively managing the Flight Path Angle, pilots can optimize energy efficiency, reduce fuel consumption, and contribute to a more sustainable aviation industry.

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