Aircraft Speeds and Airspeed Indicators

The speed at which an aircraft should not exceed. It is indicated by a blue line on an airspeed indicator.

Modern airspeed indicators are designed to display the calibrated airspeed, which is the airspeed corrected for installation and instrument errors.

The captain is initially limited by the Maximum Operating Mach Number (MMO) during descent. Below a certain flight level, the limiting factor becomes the Maximum Operating Speed (VMO).

Anemometers are calibrated using St-Venant's formula, which accounts for the compressibility of air at higher speeds.

The airspeed indicator measures the total pressure, which is the sum of static pressure and dynamic pressure.

Indicated Airspeed (IAS) is the airspeed reading directly from the airspeed indicator without any corrections for errors or installation effects.

Calibrated Airspeed (CAS) is the IAS corrected for installation and instrument errors. It provides a more accurate representation of the aircraft's speed.

True Airspeed (TAS) is the actual speed of the aircraft over the ground, taking into account wind effects and other factors.

Groundspeed (GS) is the actual speed of the aircraft over the ground, taking into account wind effects.

Mach number is independent of outside temperature. It is a ratio of true airspeed to the speed of sound.

The Mach indicator works based on the pressure difference between total pressure (Pt) and static pressure (Ps).

The Mach Number is calculated by dividing the true airspeed by the local speed of sound.

The indication of Mach number is obtained from an Air Data Computer (ADC).

As altitude increases, at a constant calibrated airspeed, the Mach number will increase.

At a constant calibrated airspeed, a change in outside temperature does not affect any of the airspeed parameters: TAS, Mach number, or GS.

The primary function of an airflow valve in an autopilot system is to regulate the airflow to the sensors that provide data for the autopilot.

Autopilot systems typically have three primary modes: Pitch attitude hold, pressure altitude hold, and heading hold. These modes allow the autopilot to maintain stable flight parameters.

During a Category II automatic approach, the radio altimeter provides the primary source of height information for the autopilot.

When CWS (control wheel steering) is engaged and the pilot releases the control wheel, the autopilot will restore the selected flight attitude and rate of turn.

A servo-actuator in an autopilot system is responsible for moving the flight control surfaces, such as ailerons, rudder, and elevator, based on the autopilot's commands.

In an autopilot system, the interplay of sensors, comparators, computers, and amplifiers processes data from the sensors, compares those data with the desired parameters, and generates control signals to the actuators.

In Altitude Hold mode, the autopilot system maintains the aircraft's altitude by adjusting the pitch attitude as needed to compensate for changes in altitude.

The synchronization system in an autopilot slaved powered control circuit ensures that the control surfaces are not deflected unnecessarily when the autopilot is disengaged. It prevents unwanted movement.

When the autopilot is in Altitude Hold mode and the pilot alters the barometric pressure setting on the altimeter, the aircraft will maintain the same altitude because the autopilot relies on pressure information from the altimeter to adjust the aircraft's pitch.

The two basic modes of an autopilot system are Altitude Hold mode and NAV mode. Altitude Hold maintains the aircraft's altitude, while NAV mode follows a pre-programmed flight path.

An autopilot system does not control engine power. Engine power is adjusted manually by the pilot.

If the synchronization system in an autopilot fails, it will prevent the autopilot from engaging. The control surfaces will remain inactive until the system is fixed or bypassed.