Aircraft Avionics and Autopilot Systems

autopilot

is a system that can significantly reduce workload during phases of flight it also refers to a collection of systems that automate a plane's operations

Lawrence Sperry (Sperry Corporation)

he developed the first aircraft autopilot

1912

When was the first aircraft autopilot was developed?

gyroscopic heading indicator and attitude indicator

indicators included in the first developed aircraft autopilot

LASER gyro

gives inertial rotation data of an aircraft

CG of the aircraft

where is laser gyro usually located

through Analog-to-Digital converter

how is frequency difference from laser gyro interpreted

cockpit instrument panel

Where is the backup attitude gyro for laser gyro located?

1. Reduce manual workload
2. Relief from small errors
3. Precision in the handling of routine tasks
4. Increased productivity

advantages of autopilot

1. Failures due to false alarms
2. Boredom
3. Over-reliance
4. Reduced alertness of operator

disadvantage of autopilot

navigation, altitude, speed, engine thrust

control inclusions of autopilot

flight route, destination, navigation

flight destination data from autopilot

Multipurpose Control and Display Unit (MCDU)

Where is the flight destination information from autopilot is displayed?

flight plan

This describes a complete flight from departure to arrival.

20

most planes that seat more than ___ people have autopilot systems

takeoff and landing

Despite having autopilot when is the FAA requires pilot to be hands-on?

TRUE

The autopilot technology and newer airport infrastructure allow for more automated landings, which are especially helpful in low visibility or bad weather events. TRUE or FALSE

Navigation Database (NDB)

contains the elements from which the flight plan is constructed

Airways, Airports, Standard terminal arrival (STAR)

NDB required information for building a flight plan.

28 days

interval for updating the navigation database

Detecting Element, Command Element, Computer Amplifier, Output Element

What are the major elements of Automatic Flight Control System?

gyro, rate gyros, accelerometer , pitot-static system and air temperature probes

What consists detecting element?

pilot's control panel, pilot's stick, rudder pedals, navigation

What consists command element?

Detecting Elements

It is considered to be internal controls or inner loop of the system.

Command Elements

It is considered to be external controls or outer loop of the system.

Computer Amplifier

This is the brain of the system, processes signal from detecting and command elements

Output elements

This element consists of units, which move the control surfaces of the aircraft based on the computer demand.

through Flight Control Unit

how autopilot mode maintains set of operating parameters

Attitude Hold, Heading Hold, Vertical Speed Hold, Altitude Hold

autopilot operating parameters

detection, amplification, correction, follow up and the aircraft response loop

basic AFCS loop consists of

follow up signal

The function of this signal is to cancel the input signal by applying an opposite signal proportional to the command required to bring the aircraft to the desired attitude.

servoactuator feedback

This signal nulls initial input error signal.

Flight Management System

FMS meaning

Area Navigation

RNAV meaning

Multipurpose Control and Display Unit

MCDU meaning

Navigation Database

NDB meaning

Auto Flight Control System

AFCS meaning

Flight Control Unit

FCU meaning

Longitudinal

X-axis

Lateral

Y-axis

Vertical

Z-axis

lateral stability

stability about the longitudinal axis

longitudinal stability

stability about the lateral axis

directional stability

stability about the vertical axis

cables

The control column on small light aircraft is physically connected to the control surfaces by these.

actuators or servo

Power assistance is provided by these on larger aircraft.

mechanical inputs or electrical inputs

actuators and servo can operate through these inputs

error correction

This is the basis for autopilot system operation.

position based and rate based

two basic ways modern autopilot systems do error correction

position based autopilot

manipulates the aircraft's controls so that any deviation from the desired attitude of the aircraft is corrected

rate based autopilot

use information about the rate of movement of the aircraft, and move control surfaces to counter the rate of change that causes the error

rate based autopilot

what autopilot system is commonly used by large aircrafts

fly-by-wire

uncommand changes is detected by gyro, accelerometers, etc. which will send electrical signals to an actuator or servo

fly-by-wire

In this electrically operated system, it is electrically signals not mechanical inputs, which control the actuator or servo operation.

avionics system

This provides the flight control computer with inputs, of heading, attitude, waypoints, etc.

Flight Control Computer (FCC)

This repositions the actuator with electrical signals to maintain the aircraft on the programmed flight path.

reduced weight, improved reliability, damage tolerance, more effective control

advantage of fly-by-wire

redundancy, complexity, cost

disadvantage of fly-by-wire