What is CADS on Boeing 777? (Central Air Data System)

The Central Air Data System (CADS) on the Boeing 777 aircraft plays a significant role in the efficient and safe operation of the aircraft. It is an essential component of the avionics system, providing critical data to the flight crew and other aircraft systems. CADS collects, processes, and distributes various air data parameters to ensure accurate and reliable flight information for navigation, performance calculations, and systems operation.

Developed by Rockwell Collins, the Central Air Data System is designed to integrate and manage the complex air data sensors and probes installed on the aircraft. It consists of multiple sensors strategically placed throughout the aircraft, including pitot tubes, static ports, angle of attack sensors, and temperature sensors. These sensors continuously measure parameters such as airspeed, altitude, vertical speed, angle of attack, and outside air temperature.

The CADS then processes the collected data, compensates for various factors such as temperature and altitude, and transmits the information to the flight instruments, flight control computers, and other avionics systems. This ensures that the flight crew has accurate and reliable information for their decision-making processes throughout the flight.

The Role of Central Air Data System

The CADS is responsible for providing critical information to the pilots in the flight deck. It displays airspeed, altitude, vertical speed, angle of attack, outside air temperature, and other related flight parameters on the Primary Flight Display (PFD) and Navigation Display (ND) located in front of each pilot. This allows the pilots to have a clear understanding of the aircraft’s performance and position relative to the surrounding environment.

In addition to displaying the data, the CADS also performs important calculations for the flight crew. It calculates the aircraft’s true airspeed, which takes into account factors such as temperature and altitude. This information is vital for determining the aircraft’s performance, fuel efficiency, and progress towards the destination. The CADS also calculates and displays the indicated airspeed, which is the airspeed read directly from the pitot tube without compensating for temperature and altitude.

Furthermore, the CADS provides information to other systems on the aircraft, including the Flight Management System (FMS) and the Autothrottle System (ATS). This enables the FMS to accurately calculate the aircraft’s position and plan the flight route, taking into account the prevailing weather conditions and other parameters. The ATS uses the airspeed information from the CADS to control the thrust produced by the engines, ensuring the aircraft maintains the desired speed and performance during different flight phases.

The Importance of Central Air Data System Reliability

Reliability is of utmost importance when it comes to the Central Air Data System on the Boeing 777. Since the CADS provides critical information for flight operations, any malfunction or inaccurate data could jeopardize the safety and efficiency of the flight. Boeing has implemented multiple redundancy measures in the CADS to ensure the system continues to function even in the face of failures.

The CADS on the Boeing 777 has three independent channels: two primary channels and one standby channel. Each primary channel consists of dedicated sensors, processing units, and displays, while the standby channel serves as a backup in the event of a failure in one of the primary channels. This redundancy ensures that even if one channel fails, the pilots still have access to accurate air data through the remaining channels.

Additionally, the CADS continuously monitors the performance and health of its sensors and components. It has built-in self-test capabilities that evaluate the integrity and accuracy of the air data inputs. If any abnormalities or discrepancies are detected, the CADS automatically alerts the flight crew and can isolate the malfunctioning sensor or system while still providing accurate information from the remaining channels.

In Conclusion

The Central Air Data System (CADS) is a crucial component of the Boeing 777 aircraft, providing accurate and reliable air data to the flight crew and other systems. It plays a vital role in flight operations, displaying important parameters, calculating performance figures, and ensuring the aircraft operates within safe and efficient limits.

Due to its critical nature, the CADS incorporates redundancy and self-monitoring capabilities to maintain reliability even in the presence of failures. This ensures that the flight crew has access to accurate air data throughout the flight, enhancing safety and enabling efficient operation of the aircraft.

For More: What is MCP on Boeing 777? (Mode Control Panel)