Attitude indicator

Attitude Indicator

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Attitude indicator

An attitude indicator (ADI), also known as

List of acronyms and initialisms: A

List of acronyms and initialisms* a - Atto* A - Ampere* A - acro ...
gyro horizon or artificial horizon, is an instrument

Flight instruments

Most aircraft are equipped with a standard set of flight instruments which give the pilot information about the aircraft's attitude, airspeed, and altitude....
used in an aircraft

Aircraft

An aircraft is a vehicle which is able to flight by being supported by the air, or in general, the atmosphere, of a planet. Examples include balloons, airplanes and helicopters....
to inform the pilot of the orientation of the aircraft relative to earth.

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Encyclopedia

An attitude indicator (ADI), also known as

List of acronyms and initialisms: A

List of acronyms and initialisms* a - Atto* A - Ampere* A - acro ...
gyro horizon or artificial horizon, is an instrument

Flight instruments

Most aircraft are equipped with a standard set of flight instruments which give the pilot information about the aircraft's attitude, airspeed, and altitude....
used in an aircraft

Aircraft

Flight dynamics

Flight dynamics is the science of aircraft and spacecraft vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw ....
or roll (side to side tilt) and yaw(left to right, right to left), and is a primary instrument for flight in instrument meteorological conditions

Instrument meteorological conditions

Instrument meteorological conditions , sometimes referred to as Blind flying, is an aviation term that describes weather conditions that normally require pilots to fly primarily by reference to instruments, and therefore under Instrument Flight Rules , rather than by outside visual references under Visual Flight Rules ....
. Attitude indicators also have significant application under visual flight rules

Visual flight rules

Visual flight rules are a set of aviation regulations with which a aviator may operate an aircraft, in a specific airspace, with meteorological conditions better than Basic VFR Weather Minimums....
, though some light aircraft do not have them installed.

Attitude indicators use a gyroscope

Gyroscope

A gyroscope is a device for measuring or maintaining orientation , based on the principles of angular momentum. The device is a spinning wheel or disk whose axle is free to take any orientation....
to establish an inertial platform. The gyroscope is geared to a display that has two dimensions of freedom, simultaneously displaying pitch and bank. The display may be colored to indicate the horizon as the division between the two colored segments (typically blue for sky and brown for ground), and is intended to be intuitive to use. The actual bank angle is calibrated around the circumference of the instrument. The pitch angle is indicated by a series of calibration lines, each representing 5° or 10° of pitch.

Most Russian-built aircraft have a somewhat different design. The background display is colored as in a Western instrument, but moves up and down only to indicate pitch. A symbol representing the aircraft (which is fixed in a Western instrument) rolls left or right to indicate bank angle.

The pitch angle is relative to the ground, which is not as helpful as knowing the angle of attack

Angle of attack

Angle of attack is a term used in aerodynamics to describe the angle between the chord of an airfoil and the vector representing the relative motion between the airfoil and the air....
of the wing, a much more critical measure of performance. The pilot must infer the total performance by using other instruments such as the airspeed indicator

Airspeed indicator

The airspeed indicator or airspeed gauge is an instrument used in an aircraft to display the craft's airspeed, typically in knot , to the Aviator....
, altimeter

Altimeter

An altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater....
, vertical speed indicator, and power instruments, e.g. an engine tachometer

Tachometer

A tachometer is an instrument that measures the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute on a calibrated analog dial, but digital displays are increasingly common....
. "Performance = Attitude + Power".

Some attitude indicators can only tolerate a specific range of bank angles. If the aircraft rolls too steeply — while performing aerobatics

Aerobatics

File:Sarang 2.jpgAerobatics is the demonstration of flight maneuvers for training, recreation or entertainment.Many aerobatic maneuvers involve rotation of the aircraft about its longtitudinal axis or the pitch axis ....
, for example — the attitude indicator can "tumble" and become temporarily unusable. For this reason, some attitude indicators are fitted with a "cage" (a device to restore the gyroscope to an erect position). Most modern attitude indicators slowly re-erect back to level after a tumble. Others do not tumble at all.

On the attitude indicator are two white or yellow horizontal lines with a dot between them. The horizontal lines of this symbolic aircraft represent the wings and the dot represents its nose. If the symbolic aircraft dot is above the horizon line (more blue background) the aircraft is nose up. If the symbolic aircraft dot is below the horizon line (more brown background) the aircraft is nose down. When the dot and wings are on the horizon line, the aircraft is in level flight.

Individual mechanical gyros are slowly being replaced by Attitude and Heading Reference Systems

Attitude and Heading Reference Systems

Attitude and Heading Reference Systems or better known as Attitude Heading Reference System are 3-axis sensors that provide heading, Aircraft attitude and Yaw angle information for aircraft....
), which use solid-state or miniature gyroscopes (MEMS gyroscope) to supply aircraft orientation information, supplemented by magnetometers to supply heading information. Historically, heading information was supplied by a separate gyroscopic instrument known as a directional gyro (DG, or heading indicator). AHRS are able to provide three-axis information that can be shared with multiple devices in the aircraft, such as "glass cockpit

Glass cockpit

A glass cockpit is an aircraft Cockpit that features electronic instrument Display device. Where a traditional cockpit relies on numerous mechanical gauges to display information, a glass cockpit utilizes several computer displays that can be adjusted to display flight information as needed....
" primary flight displays (PFD

PFD

selfref|On Wikipedia, PfD may mean...
s). AHRS have been proven to be highly reliable and are in wide use in commercial and business aircraft. Recent advances in MEMS manufacturing have brought the price of FAA

Federal Aviation Administration

The Federal Aviation Administration is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of civil aviation in the U.S....
-certified AHRS down to less than $15,000, making them practical for general aviation

General aviation

General aviation is one of two categories of civil aviation. It refers to all flights other than military aviation and scheduled air transport flights, both private aviation and commercial aviation....
aircraft. If an aircraft's ADIs have failed there is a standby ADI located in the center of the instrument panel, where other standby basic instruments such as the airspeed indicator and the attitude indicator are also available. These mostly mechanical standby instruments are available even if the electronic flight instruments fail.