What is DIU on Boeing 737? (Digital Interface Unit)

The Digital Interface Unit (DIU) plays a crucial role in the operation of the Boeing 737 aircraft. It serves as a communication hub, connecting various systems and components within the aircraft. The DIU acts as an interface between the cockpit and the aircraft’s avionics, allowing pilots to interact with the digital systems and display units.

The DIU is responsible for processing, converting, and distributing data between different systems, including the Flight Management Computer, Autopilot, Weather Radar, and various display units. It ensures that the information displayed to the pilots is accurate and up to date.

As a critical component of the aircraft, the DIU undergoes rigorous testing and certification processes to ensure its reliability and performance. It must meet stringent standards and comply with aviation regulations, such as those set by the Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA).

Digital Interface Unit Functionality

The DIU serves multiple functions on the Boeing 737 aircraft. Let’s explore some of its key functionalities:

1. Data Processing and Conversion

The DIU receives data inputs from various systems and sensors on the aircraft, such as the Inertial Reference System (IRS), Global Positioning System (GPS), and Air Data Inertial Reference Unit (ADIRU). It processes and converts these inputs into a format that can be displayed on the cockpit instruments and displays.

For example, the DIU receives navigation data from the Flight Management Computer (FMC) and converts it into a format that can be displayed on the Navigation Display (ND) in the cockpit. It also receives weather radar data and converts it into a format that can be displayed on the Weather Radar display unit.

The DIU ensures that the data received from various systems is accurate, reliable, and synchronized. It performs data integrity checks to identify any discrepancies or errors in the received data, allowing the pilots to make informed decisions based on accurate information.

2. Communication and Integration

The DIU acts as a central communication hub, facilitating the exchange of information between different systems and components within the aircraft. It integrates various avionic systems, including the Autopilot, Flight Director, and Engine Indication and Crew Alerting System (EICAS).

Through its communication and integration capabilities, the DIU enables seamless coordination between different systems, enhancing the overall performance and efficiency of the aircraft. It ensures that critical information is shared accurately and timely, allowing for effective decision-making by the flight crew.

Furthermore, the DIU interfaces with the aircraft’s data buses, such as the ARINC 429 and ARINC 629, allowing for the exchange of digital information between different avionic systems. This digital communication eliminates the need for traditional analog connections, reducing weight and complexity within the aircraft.

3. System Monitoring and Diagnostics

The DIU also plays a vital role in monitoring and diagnosing the health and performance of various systems on the aircraft. It receives data inputs from sensors and systems, such as the Central Maintenance Computer (CMC), and performs real-time monitoring and analysis.

By continuously monitoring the status of different systems, the DIU can detect any abnormalities or malfunctions. It alerts the flight crew through warning messages or visual indications, allowing them to take appropriate actions to address the issues and ensure the continued safe operation of the aircraft.

The DIU also supports maintenance activities by providing diagnostic information to ground maintenance crews. It logs and stores data regarding system performance and faults, which can be retrieved and analyzed during maintenance inspections.


The Digital Interface Unit (DIU) is a vital component of the Boeing 737 aircraft, enabling efficient communication, integration, and operation of various avionic systems. It processes and converts data, facilitates information exchange, and monitors system health and performance. The DIU plays a crucial role in ensuring the safe and reliable operation of the aircraft, enhancing the overall flight experience for both the flight crew and passengers.

External Links

For more information about the Boeing 737 aircraft and its avionic systems, you can visit the official Boeing website here.

For More: What is SID on Boeing 737? (Standard Instrument Departure)