What is CDU on Boeing 737? (Control Display Unit)

The Control Display Unit (CDU) is a crucial component of the Boeing 737 aircraft’s flight management system. It serves as the interface between the pilots and the aircraft’s computer system, allowing them to input and receive important information for navigation, communication, and control of the aircraft during various phases of flight. The CDU is located on the center pedestal in the cockpit and is operated using a combination of buttons, knobs, and a keypad.

The CDU’s primary function is to enter and manage flight plans, which include waypoints, routes, altitudes, and speeds. Pilots can input this information manually or retrieve it from the onboard database. The CDU also displays critical aircraft information such as engine parameters, fuel quantities, system status, and various other operational data.

Key Functions of the CDU

The Control Display Unit on the Boeing 737 has several key functions that contribute to its importance in operating the aircraft efficiently and safely:

1. Flight Planning and Management

The CDU is primarily used for flight planning and management. Pilots can input flight plans, including waypoints and routes, using the keypad, buttons, and knobs on the CDU. The flight plan is then stored in the aircraft’s computer system, which uses it to calculate and display navigational information such as distances, fuel consumption, and estimated time of arrival.

The CDU also allows pilots to make real-time changes to the flight plan, such as altering the route, adding or removing waypoints, and adjusting speeds and altitudes. These changes are instantly reflected in the aircraft’s navigation system, providing pilots with accurate and up-to-date information about the flight.

2. Performance Monitoring

Another important function of the CDU is performance monitoring. It provides pilots with essential information about the aircraft’s engines, fuel consumption, and system status. The CDU displays data such as engine parameters (N1, N2, EGT, etc.), fuel quantities, hydraulic pressures, electrical system status, and various other operational parameters.

This real-time monitoring helps pilots identify any anomalies or issues with the aircraft’s performance, allowing them to take appropriate actions. For example, if the CDU displays abnormal engine parameters, pilots may decide to adjust thrust settings or notify maintenance personnel for further investigation.

Design and Interface

The Control Display Unit on the Boeing 737 is designed to be user-friendly and intuitive for pilots. Its interface consists of a liquid crystal display (LCD) screen, a keypad with alphanumeric keys, and various buttons and knobs for navigation and input purposes.

The LCD screen displays the information entered by pilots and the output received from the aircraft’s systems. The keypad allows pilots to input alphanumeric characters and numerical values for flight planning and data entry. The buttons and knobs are used to navigate through different CDU pages, select options, and make menu selections.

The CDU’s interface follows a logical flow, enabling pilots to easily access different functionalities and navigate through the system. The buttons and knobs are strategically placed to minimize the risk of unintentional inputs and provide a tactile feel for better control.

Overall, the design and interface of the Control Display Unit on the Boeing 737 ensures that pilots can efficiently interact with the aircraft’s flight management system, enhancing their ability to operate the aircraft smoothly and safely.


The Control Display Unit (CDU) plays a vital role in the operation of the Boeing 737 aircraft. It serves as the interface between the pilots and the aircraft’s computer system, enabling them to input and retrieve crucial information for flight planning, management, and performance monitoring.

The CDU’s functions include flight planning and management, real-time updates to the flight plan, performance monitoring, and displaying critical aircraft information. Its user-friendly design and intuitive interface contribute to its effectiveness in helping pilots operate the aircraft efficiently and safely.

As technology continues to advance, the CDU’s capabilities will likely evolve to enhance pilot convenience and improve flight management systems. However, its crucial role in ensuring the safe and efficient operation of the Boeing 737 aircraft will remain unchanged.

For More: What is EICAS on Boeing 737? (Engine Indicating And Crew Alerting System)