What is COM/NAV on Boeing 737? (Communication/Navigation)

The Boeing 737 is one of the most widely used aircraft in the world, known for its reliability and versatility. It has been in operation for several decades and has undergone many updates and improvements. One crucial aspect of the Boeing 737’s functionality is its Communication/Navigation (COM/NAV) system. In this article, we will explore what the COM/NAV system is and how it contributes to the safe and efficient operation of the aircraft.

Communication/Navigation on the Boeing 737

The Communication/Navigation system on the Boeing 737 is a complex network of avionics and equipment that allows the aircraft to communicate with air traffic control (ATC) and navigate through the skies. It encompasses various components and technologies, all working together to ensure accurate communication and efficient navigation. Let’s delve deeper into each aspect of the COM/NAV system:


Effective communication is essential for the safe and successful operation of any aircraft. The COM part of the COM/NAV system on the Boeing 737 is responsible for facilitating communication between the aircraft and the ground, other aircraft, and air traffic control. This is achieved through voice and data transmissions.

The primary communication system on the Boeing 737 is the VHF (Very High Frequency) radio system. This system operates within a frequency range of 118 to 137 MHz and allows pilots to communicate with ATC and other aircraft in their vicinity. VHF radio transmissions rely on line-of-sight communication, which means they are limited by the curvature of the Earth and other obstacles.

In addition to the VHF radio system, the Boeing 737 also features other communication tools, such as SELCAL (Selective Calling), which allows pilots to receive selective calls from ATC without constantly monitoring the radio frequency, and ACARS (Aircraft Communications Addressing and Reporting System), a digital communications network used for various purposes, including sending and receiving operational messages, weather updates, and flight plans.

The COM system on the Boeing 737 ensures clear and efficient communication, enabling pilots to receive essential instructions, updates, and alerts from ATC. It plays a crucial role in maintaining situational awareness and ensuring the safe navigation of the aircraft.


The NAV part of the COM/NAV system on the Boeing 737 is responsible for accurate navigation and positioning of the aircraft. It provides pilots with essential information about their location, heading, altitude, and other flight parameters. The navigation system on the Boeing 737 consists of various components, including:

1. Inertial Navigation System (INS): The INS is a crucial part of the navigation system and provides accurate position data by constantly monitoring the aircraft’s acceleration and rotation rates. It is based on the principle of integrating these measurements over time to track the aircraft’s movement relative to a known starting point. Modern Boeing 737 models use advanced INS technology, such as the IRS (Inertial Reference System), which combines laser gyros and accelerometers to provide precise navigation data.

2. Global Navigation Satellite System (GNSS): The Boeing 737 is equipped with a GNSS, which utilizes a network of satellites to provide precise positioning information. The most commonly used GNSS is the GPS (Global Positioning System), which can determine the aircraft’s location with remarkable accuracy. The GNSS on the Boeing 737 works in conjunction with the INS to provide redundancy and enhance navigation reliability.

3. Flight Management System (FMS): The FMS is a sophisticated computer system that integrates various data sources, including the GNSS and INS, to compute and display the aircraft’s optimal flight path. It takes into account factors such as wind speed, altitude restrictions, and airway congestion to plan the most fuel-efficient and time-saving route. Pilots can input their desired route and waypoints into the FMS, and the system will guide the aircraft accordingly.

The navigation system on the Boeing 737 provides pilots with accurate and up-to-date information about their position, helping them navigate through complex airspaces, avoid obstacles, and arrive at their destinations safely and efficiently.

Integration and Redundancy

The COM/NAV system on the Boeing 737 is designed with a high level of integration and redundancy to ensure the availability and reliability of critical functions. Integration refers to the seamless coordination between different components of the system, allowing them to share and exchange data seamlessly. Redundancy, on the other hand, involves the duplication of key components or systems to provide backup in case of a failure.

The integration and redundancy of the COM/NAV system on the Boeing 737 enhance the aircraft’s safety and reliability. Even in the event of a failure or malfunction in one component, other redundant systems can take over and continue to provide essential communication and navigation functions. This redundancy minimizes the risk of complete system failure and ensures that pilots have the necessary tools to safely operate the aircraft.

Overall, the COM/NAV system on the Boeing 737 is a critical component that enables effective communication with air traffic control and precise navigation throughout the flight. The integration of various communication and navigation technologies, along with redundancy measures, ensures the safety and efficiency of the aircraft’s operations.

For More: What is LAN on Boeing 737? (Local Area Network)