What is SG on Boeing 737? (Symbol Generator)

Symbol Generator (SG) plays a crucial role in the functioning of the Boeing 737 aircraft. As one of the essential systems onboard, the Symbol Generator is responsible for generating various symbols and displays that provide critical information to the flight crew. In this article, we will delve into the workings of the Symbol Generator on the Boeing 737, exploring its functions, importance, and how it contributes to the safe operation of the aircraft.

The Role of Symbol Generator

The Symbol Generator on the Boeing 737 is a vital component of the aircraft’s flight deck. It works in conjunction with other systems to provide the flight crew with important information through various displays, such as the primary flight displays (PFDs), navigation displays (NDs), and the multi-function displays (MFDs).

The SG receives inputs from sensors and systems throughout the aircraft, including the flight management computer (FMC), inertial reference system (IRS), air data computer (ADC), navigation radios, and other critical instruments. It processes these inputs and generates the appropriate symbols and displays to present the necessary information to the flight crew.

One of the primary functions of the Symbol Generator is to display the aircraft’s attitude, altitude, airspeed, and navigation information. The attitude symbol represents the aircraft’s pitch and roll, providing a clear indication of its orientation in relation to the horizon. The altitude symbol displays the current altitude, enabling the crew to monitor and adjust the aircraft’s vertical position. The airspeed symbol provides real-time information about the aircraft’s speed, while the navigation symbols assist the crew in following the desired flight path.

Integration with Autopilot and Flight Control Systems

The Symbol Generator on the Boeing 737 is closely integrated with the aircraft’s autopilot and flight control systems. It works in tandem with these systems to display the autopilot mode, flight director commands, and various flight control modes.

The autopilot mode indicates whether the autopilot is engaged or disengaged. When engaged, the SG provides visual cues to confirm the autopilot’s mode, such as heading hold, altitude hold, or vertical speed hold. Additionally, the SG displays the flight director commands, which guide the pilots in adhering to the desired flight path.

Furthermore, the Symbol Generator also presents the various flight control modes, including normal law, alternate law, and direct law. These modes determine the behavior and limits of the aircraft’s flight control surfaces, ensuring safe and optimal handling characteristics in different flight conditions.

Ensuring Safety and Reliability

The Symbol Generator on the Boeing 737 is designed with safety and reliability in mind. It undergoes rigorous testing and certification processes to meet stringent aviation standards. Additionally, it is equipped with redundancies and fail-safe mechanisms to ensure continued operation in the event of a failure.

In the context of the Symbol Generator, redundancy refers to the presence of backup systems or components that can assume control in case of a primary system failure. For example, if one SG fails, another SG can take over its functions seamlessly without any disruption to the flight crew’s access to critical flight information.

Furthermore, the Symbol Generator is interconnected with other systems through the aircraft’s electrical and data networks. This interconnectivity allows for enhanced system monitoring and fault detection. In the event of a fault or abnormal condition, the SG can alert the flight crew by generating appropriate caution or warning symbols, enabling them to take appropriate action to address the situation.

Overall, the Symbol Generator on the Boeing 737 ensures the dissemination of accurate and reliable information to the flight crew, contributing to the safe operation of the aircraft.

For More: What is CFDS on Boeing 737? (Centralized Fault Detection System)