In the context of aviation and aerospace, "Autothrottle" (also known as "Auto Throttle" or "A/THR") refers to a system that automatically controls an aircraft's throttle setting to maintain a set speed or performance parameter. The autothrottle system is designed to reduce pilot workload, optimize engine performance, and improve overall flight efficiency.

The autothrottle system typically consists of a combination of sensors, computers, and actuators that work together to control the throttle setting. The system uses data from various sources, such as:

1. Air data computers (ADCs)
2. Inertial reference systems (IRS)
3. Accelerometers
4. Engine sensors (e.g., N1, N2, or EPR)

The autothrottle system can operate in various modes, including:

1. Speed mode: Maintains a set airspeed (e.g., Mach number or knots)
2. Mach mode: Maintains a set Mach number
3. Thrust mode: Maintains a set thrust setting (e.g., percent of maximum thrust)
4. Altitude mode: Maintains a set altitude or rate of climb/descent

When the autothrottle system is engaged, it adjusts the throttle setting to maintain the desired performance parameter. The system can also interact with other aircraft systems, such as the autopilot and flight management system (FMS), to ensure a smooth and efficient flight profile.

The benefits of autothrottle include:

1. Reduced pilot workload
2. Improved fuel efficiency
3. Enhanced safety (e.g., reduced risk of overspeed or underspeed)
4. Simplified engine management
5. Increased automation and reduced pilot fatigue

Autothrottle systems are commonly used in modern commercial and business aircraft, as well as in some military and general aviation aircraft. However, it's essential to note that the specific implementation and capabilities of autothrottle systems can vary depending on the aircraft model and manufacturer.