Term
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Definition
| Distance of the aircraft above the ground Synonyms: radar altitude; |
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Term
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Definition
| Distance of the aircraft above mean sea level |
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Term
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Definition
| A standard, fixed reference, as opposed to moving reference; Compare: relative; |
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Term
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Definition
| Rate of change of velocity, either scalar or vector, often with subscripts such as ENU or XYZ to denote the coordinate frame; time derivative of velocity; time integral of jerk; Symbols: a, A; Typical Units: ft/s-squared, g; Dimensions: Length / Time-squared; |
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Term
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Definition
| Aircraft acceleration in true east direction; Symbols: A sub E; Typical Units: ft/s-squared; Dimensions: Length / Time-squared; |
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Term
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Definition
| Aircraft acceleration in true north direction; Symbols: A sub N; Typical Units: ft/s-squared; Dimensions: Length / Time-squared; |
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Term
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Definition
| An inertial device for measuring acceleration, usually in three orthogonal axes (lateral X, longitudinal Y, and vertical Z); accelerometers usually consist of a mass, spring, and damper; accelerometers are usually included in inertial sensors, such as AHRS and INS; |
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Term
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Definition
| To allow to proceed, for example with a position update, usually by an operator; Compare: reject |
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Term
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Definition
| Measure of exactness, possibly expressed in percent; Compare: precision |
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Term
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Definition
| Measure of exactness, possibly expressed in percent; Compare: precision |
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Term
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Definition
| To begin performing a mission objective, such as flying along a radial of a radio station; usually refers to a mode of radio navigation, such flying along that radial after capturing that radial; See Also: capture criterion; Compare: arm, capture; |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| Automatic Direction Finding |
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Term
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Definition
| A signal to indicate safe or normal configuration, condition of performance, operation of essential equipment, or to attract attention and impart information for routine action purposes (from MIL-STD-1472D); an annunciator that is the least critical (less than a caution or a warning); |
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Term
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Definition
| Automatic flight control system |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| Straight-line distance from the aircraft to a point on the ground; |
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Term
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Definition
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Term
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Definition
| Attitude Heading Reference System |
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Term
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Definition
| A process by which one or more sensors provide data to another sensor to produce results better than any single sensor; aiding occurs at the data source level or at the physical device level, depending upon specific implementation of the device and the data source (choice of implementation is transparent above the data source); aiding is automatically controlled by software without input from an operator; a basic control to a data source from navigation, radio navigation, or other devices Compare: update; |
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Term
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Definition
| A control surface on fixed-wing aircraft, usually mounted on the aft edge of wings, that controls roll, and is controlled by the wheel; Symbols: delta sub A; Typical Units: rad, deg; |
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Term
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Definition
| A primary navigation data source. A navigation sensor based on atmospheric data sensors; usually measures static pressure, dynamic pressure, and outside air temperature; sometimes computes other atmospheric data, such as indicated airspeed, Mach number, calibrated airspeed As a guidance mode, ADC is least accurate of the listed modes and is used only as a last resort. |
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Term
| Air data dead reckoning (ADDR) |
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Definition
| Dead reckoning navigation based on simple instruments as source (barometric altimeter, magnetic compass, airspeed indicator, known wind conditions); sometimes called dead reckoning; |
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Term
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Definition
| Straight-line distance from the aircraft to a point on the ground; |
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Term
| Air-mass flight path angle |
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Definition
| Angle in vertical plane of earthspeed vector and groundspeed vector; occasional definition for flight path angle; Compare: earth-referenced flight path angle; Symbols: gamma sub A; Typical Units: rad, deg; |
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Term
| Air Traffic Control (ATC) |
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Definition
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Term
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Definition
| A craft that flies in the air; either fixed or rotary wing. |
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Term
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Definition
| See Also: state data, true airspeed, indicated airspeed, calibrated airspeed; Symbols: V sub A/S; Typical Units: kt, ft/s; Dimensions: Length / Time; |
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Term
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Definition
| A standard model for computing earth data |
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Term
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Definition
| A basic control to a data source from controls and displays to align a device. Also a procedure to align physical devices, usually navigation sensors, so that they provide the most accurate results possible; commonly required by INS, AHRS, barometric altimeter; See Also: boresighting, calibration, initialization; |
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Term
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Definition
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Term
|
Definition
| A device to measure altitude, either barometric altitude or radar altitude |
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Term
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Definition
| Height, usually with respect to the terrain below (radar altitude, feet above closest dirt) or fixed earth reference (barometric altitude, feet above mean sea level); Symbols: h; Typical Units: ft; Dimensions: Length; |
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Term
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Definition
| A basic output from guidance to flight director, indicating the difference between actual altitude and desired altitude; Symbols: DELTA h; Typical Units: ft; Dimensions: Length |
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Term
| Altitude error scale factor (KZSF) |
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Definition
| A guidance control law parameter, generated by the vertical guidance modes; varies control authority of vertical guidance |
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Term
| Altitude integral gain (KALTINT) |
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Definition
| A guidance control law parameter, generated by the vertical guidance modes; varies control authority of the altitude integral in vertical guidance, to reduce steady-state errors in altitude error Typical Units: ft; Dimensions: Length; |
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Term
| Altitude integral input (ALTINTVAL) |
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Definition
| A guidance control law parameter, generated by the vertical guidance modes; a reference altitude for reducing steady-state errors in altitude error Typical Units: ft; Dimensions: Length; |
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Term
| Altitude integral limit (INTMAGLIM) |
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Definition
| A guidance control law parameter, generated by the vertical guidance modes; limits the magnitude of altitude integral value Typical Units: ft; Dimensions: Length; |
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Term
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Definition
| The difference between pitch and the air-referenced flight path angle; the angle between the aircraft center line and the airspeed vector in the vertical plane, positive when the nose is up; Symbols: alpha; Typical Units: rad, deg; |
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Term
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Definition
| Rate of change of angular velocity, either scalar or vector, often with subscripts such as XYZ to denote the coordinate frame; time derivative of angular position; time integral of angular acceleration; Symbols: alpha; Typical Units: rad/s-squared; Dimensions: 1/Time-squared; |
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Term
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Definition
| Amount of rotation about an axis, either scalar or vector, often with subscripts such as XYZ to denote the coordinate frame; time integral of angular velocity; Synonyms: angle; Symbols: theta; Typical Units: rad, deg; |
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Term
|
Definition
| Rate of change of rotation about an axis, either scalar or vector, often with subscripts such as XYZ to denote the coordinate frame; time derivative of angular position; time integral of angular acceleration; See Also: tachometer; Symbols: omega; Typical Units: rad/s, rpm; Dimensions: 1/Time; |
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Term
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Definition
| Any one of warning, caution, or advisory; Synonyms: alert; |
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Term
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Definition
| A process that executes based on events rather than a fixed rate, it is not synchronized to other processes of interest; Compare: periodic; |
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Term
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Definition
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Term
|
Definition
| To fly towards a point; a basic guidance mode, providing lateral guidance, longitudinal guidance, and vertical guidance to a point at an operator selected groundspeed and radar altitude; See Also: waypoint approach, ILS approach, rendezvous approach; |
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Term
|
Definition
| Hover approach of a rotary wing aircraft. |
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Term
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Definition
| To strive for a mission objective, such as flying toward a radial of a radio station; usually refers to a mode of radio navigation, such as striving to reach a specific radial of a radio station prior to flying along that radial; See Also: capture criterion; Compare: activate, capture; |
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Term
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Definition
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Term
|
Definition
| Latitude measured with respect to vector of apparent gravity; Compare: geocentric latitude, geodetic latitude; Symbols: Phi sub A; Typical Units: rad, deg,DMS; |
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Term
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Definition
|
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Term
|
Definition
| Environmental data related to the atmosphere at some point of interest |
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Term
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Definition
| The primary aircraft angles in the state vector; pitch, roll, and yaw; |
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Term
| Attitude Heading Reference System (AHRS) |
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Definition
| Combines information from a Magnetic Heading Sensor with self-contained aircraft acceleration data to provide attitude, heading, position, body inertial velocity, and body inertial acceleration. Typically a low-accuracy, self-contained navigation source using strapdwon accelerometers; |
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Term
|
Definition
| A standard model for computing earth data |
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Term
| Automatic Direction Finding (ADF) |
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Definition
| A basic guidance mode, providing lateral guidance to a radio station. Equipment that determines bearing to a radio station; |
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Term
| Automatic flight control system (AFCS) |
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Definition
| An automated system for controlling the primary flight controls, often with built-in functions for guidance and flight director, and sometimes radio navigation; many flight control systems include basic instruments similar to a AHRS; many flight control systems accept flight director inputs so that its radio navigation, guidance, and flight director can be bypassed |
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Term
|
Definition
| A mode of an automatic flight control system which controls primary flight controls to meet specific mission objectives, such as maintain a heading or altitude; Synonyms: automatic flight control system; |
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Term
|
Definition
| A mode of an automatic flight control system which controls primary flight controls to meet specific mission objectives, such as maintain a heading or altitude; Synonyms: automatic flight control system; |
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Term
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Definition
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Term
|
Definition
| One direction in an orthogonal reference frame; |
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Term
|
Definition
| An angle in the horizontal plane, usually measured with respect to body coordinates |
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Term
|
Definition
| Barometric altitude select |
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Term
|
Definition
| A filter that allows frequencies between two cutoff frequencies to pass while attenuating frequencies outside the cutoff frequencies; a band-pass filter can be constructed as the composition of a low-pass filter and a high-pass filter; |
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Term
|
Definition
| The angle between the horizontal plnase and the right wing in the lateral plane, positive when the right wing is down; Synonyms: roll; Symbols: phi,Phi; Typical Units: rad, deg; |
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Term
|
Definition
| Height with respect to fixed earth reference (above mean sea level); Synonyms: pressure altitude; Symbols: h sub b; Typical Units: ft; Dimensions: Length; |
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Term
| Barometric altitude select (BALT SEL) |
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Definition
| A basic guidance mode, providing vertical guidance to an operator selected barometric altitude; |
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Term
|
Definition
| Height with respect to fixed earth reference (barometric altitude, feet above mean sea level); Synonyms: pressure; Symbols: p sub a; Typical Units: in HG,mbar; Dimensions: Mass /Time-squared * Length; |
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Term
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Definition
|
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Term
|
Definition
| A device, usually based on the ground, that aids in determining position or direction; |
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Term
|
Definition
| Direction on a compass; Synonyms: direction; Symbols: B; Typical Units: rad, deg; |
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Term
|
Definition
| A standard model for computing earth data |
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Term
|
Definition
| An offset applied to a measurement for error correction; Synonyms: offset |
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Term
|
Definition
|
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Term
|
Definition
| The aircraft, usually referring to a coordinate system; |
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Term
|
Definition
| Coordinates referenced to the body of the aircraft; See Also: XYZ; Compare: earth coordinates, stability coordinates |
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Term
|
Definition
| The angle between the center line of a sensor and aircraft center line, either by design or by misalignment; |
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Term
|
Definition
| The angle between the center line of a sensor and aircraft center line, either by design or by misalignment; |
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Term
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Definition
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Term
|
Definition
|
|
Term
| Built-in simulation (BIS) |
|
Definition
| Function in avionics software that simulates sensors, aircraft, and pilot, to exercise avionics software (including navigation, radio navigation, guidance and flight director); BIS is often used by a development team to check basic operation following installation of new software or patches; BIS is seldom used by aircraft flight crews or maintenance crews; Compare: real-time engineering simulation; |
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Term
|
Definition
| Term defining role of device on a MIL-STD-1553 bus as being master; Compare: remote terminal; |
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Term
| Calibrated airspeed (CAS) |
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Definition
| Indicated airspeed corrected for instrumentation errors, but not for air density; See Also: airspeed; Symbols: V sub 'CAS'; Typical Units: kt,ft/s; Dimensions: Length / Time; |
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Term
|
Definition
| A basic control to a data source from controls and displays for calibrating a device; Also, a procedure to adjust physical devices so that they provide the most accurate results possible; calibration procedures commonly result in correction factors to be downloaded from the host processor to the device; during calibration, the device is usually not available; See Also: alignment, boresighting, initialization; |
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Term
|
Definition
| Angle of nacelle mounting; Typical Units: rad, deg; |
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Term
|
Definition
| To attain an objective, such as reaching a radial of a radio station; See Also: capture criterion; Compare: activate, arm; |
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Term
|
Definition
| A test case to determine if an armed objective has been captured; In avionics, an aircraft might have an objective to fly to a radial of a radio station, then to fly along it. While enroute, the objective is armed, meaning that the crew and software are attempting to reach the radial. The radial is captured and the objective is met when the capture criteria are met. In this case, the capture criterion might be bearing to the radio station is within 5deg of 270deg. An objective can have multiple criteria. Capture criterion are often used with radio navigation to determine a transition from armed to active. |
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Term
|
Definition
|
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Term
|
Definition
| A signal which alerts the operator to an impending dangerous condition requiring attention, but not necessarily immediate action (from MIL-STD-1472D); an annunciator that is more critical than an advisory but less critical than a warning; |
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Term
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Definition
|
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Term
|
Definition
|
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Term
|
Definition
| Circular error probability |
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Term
|
Definition
| A number that maps to a frequency; |
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|
Term
| Circular error probability (CEP) |
|
Definition
| A probability that a percentage of two-dimension measurements will lie within a circle of given radius, with the circle centered at truth or mean of the measurements; Compare: radial error probability, spherical error probability; CEP specifies test cases for measurement errors of sensors of two dimensions, such as velocity east and north. |
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Term
|
Definition
| A standard model for computing earth data |
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|
Term
| Circular error probability (CEP) |
|
Definition
| A probability that a percentage of two-dimension measurements will lie within a circle of given radius, with the circle centered at truth or mean of the measurements; Compare: radial error probability, spherical error probability; CEP specifies test cases for measurement errors of sensors of two dimensions, such as velocity east and north. |
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Term
|
Definition
| A standard model for computing earth data |
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Term
|
Definition
| A flight control operated by moving up or down with hand in rotary-wing aircraft, primarily to control lift (altitude); controls collective (total) pitch of the rotors on a rotary-wing aircraft; |
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Term
|
Definition
| A flight control operated by moving up or down with hand in rotary-wing aircraft, primarily to control lift (altitude); controls collective (total) pitch of the rotors on a rotary-wing aircraft; |
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Term
|
Definition
| Controls given to a device, not that the device necessarily obeyed the controls |
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Term
|
Definition
| How well equipment is communicating; Values: operational, degraded, failed |
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Term
|
Definition
| A filter in which the complement of the filter is desired, giving the effect of a high-pass filter by implementing a low-pass filter; a filter for combining multiple data sources, usually of different types, by adding filtered values, where the sum of the filters in the frequency domain is unity; a Kalman filter with fixed gains; Complementary filters are often designed in the frequency domain in way that that the filters determined at build time such that the cutoff frequency of the LFP is equal to that of the HPF. This provides the advantages of DNS's long-term accuracy and INS's short-term accuracy, while filtering DNS's high-frequency noise and INS's slow drift. Compare: averaging filter, Kalman filter; |
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Term
|
Definition
| In a periodic, cyclical computer system, the most basic, fastest timing loop |
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Term
|
Definition
| Time which can have any point expressed as a real quantity, without regard for any specific interval or processing rate; Compare: discrete time; |
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Term
|
Definition
| A mathematical relationship to describe a function of time, expressed in terms of continuous time; Compare: difference equation, differential equation, discrete-time equation, Laplace transform, state-space model, Z transform; See Also: first-order filter, second-order filter, unit functions for examples; |
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Term
|
Definition
| The mathematical definition of a system used to control or to change the dynamic response of a system; |
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Term
|
Definition
| An airfoil attached to an aircraft that is moved to control the attitude of the aircraft; an surface to control flight of an aircraft indirectly, such as a swashplate to control pitch of rotor blades; See Also: aileron, rudder, spoiler, elevator, flaps, trim tab, stabilizer; Symbols: delta; Typical Units: rad, deg; |
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Term
| Controlled altitude (CTALT) |
|
Definition
| A guidance control law parameter, generated by the vertical guidance modes; altitude that is being controlled Typical Units: ft; Dimensions: Length; |
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Term
|
Definition
| A guidance control law parameter, generated by the longitudinal guidance modes; speed that is being controlled Typical Units: ft/s, kt; Dimensions: Length / Time; |
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Term
|
Definition
| Tangential acceleration caused by motion on a radial on a rotating surface, in aviation, it is acceleration in the earth's longitudinal direction caused by changing latitude, usually computed from system state data; Symbols: a sub c; Typical Units: ft/s-squared,g; Dimensions: Length / Time-squared; |
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Term
|
Definition
| Measured pressure altitude corrected for instrumentation errors |
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Term
|
Definition
| Describes operation of flight director in which automatic flight control system causes flight controls to follow commands from flight director or errors from guidance |
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Term
|
Definition
| Towards a point at a specified course; Compare: direct |
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Term
|
Definition
| A guidance control law parameter, generated by the lateral guidance modes; limits the intercept angle of the flight path with a desired course, typically 45deg Typical Units: deg, rad; |
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Term
|
Definition
| A pattern of equally spaced parallel lines followed for searching the ground from an aircraft; Compare: expanding square search, sector search; |
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Term
|
Definition
| Perpendicular to the course; |
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|
Term
| Crosstrack deviation (XTKD) |
|
Definition
| A guidance control law parameter, generated by the lateral guidance modes; distance from the aircraft to a desired course measured along a prependicular to the course Typical Units: ft; Dimensions: Length; |
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Term
|
Definition
| Perpendicular to the course; |
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Term
| Crosstrack deviation gain (KXTKD) |
|
Definition
| A guidance control law parameter, generated by the lateral guidance modes; relative weighting of crosstrack deviation in the lateral control law Typical Units: rad/ft; Dimensions: 1/L; |
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Term
| Crosstrack deviation rate (XTKR) |
|
Definition
| A guidance control law parameter, generated by the lateral guidance modes; rate of change of crosstrack deviation Typical Units: ft/s; Dimensions: Length / Time; |
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Term
| Crosstrack deviation rate gain (KXTKR) |
|
Definition
| A guidance control law parameter, generated by the lateral guidance modes; relative weighting of the crosstrack deviation rate in the lateral control law Typical Units: s; Dimensions: Time; |
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Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| A indicator to an operator for control placement, tells the operator where to place controls; Synonyms: command |
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Term
|
Definition
| See: moding cursor, target cursor |
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Term
|
Definition
| The frequency at which the gain of a filter is at an edge of a band, usually taken to be when gain is 0.5, or -3.01dB; the frequency at which the output of a filter is half the power of the input; See Also: band-pass filter, high-pass filter, low-pass filter; Symbols: omega sub c; Typical Units: rad/s,Hz; Dimensions: 1/Time; |
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Term
|
Definition
| See: longitudinal cyclic, lateral cyclic; |
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Term
|
Definition
| The frequency of oscillation of an underdamped second-order filter; See Also: second-order filter; Symbols: omega; Typical Units: rad/s,Hz; Dimensions: 1/Time; |
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Term
|
Definition
| Control parameter for a second order filter. Symbols: zeta; |
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Term
|
Definition
| Software that receives data from a physical device, translates the data into standard units, maintains equipment status, and provides a common interface for each variation of a particular device; |
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Term
| Data Transfer System (DTS) |
|
Definition
| A device for transferring data with avionics, similar to a diskette drive; |
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Term
|
Definition
| A method of navigation based on basic information (barometric altitude, magnetic heading, airspeed, wind conditions) from best available source; sometimes short for air data dead reckoning; |
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Term
|
Definition
|
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Term
|
Definition
| A guidance mode providing lateral guidance, longitudinal guidance and vertical guidance for a set heading or bank angle, a set speed, and a set climb rate, altitude or pitch; |
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Term
|
Definition
| Rate of change, usually with respect to time; Symbols: x dot, x prime, x sup (1), dx/dt, Dx; |
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Term
|
Definition
| Calculated values for which no direct measurement exists; Compare: estimated, filtered, measured, raw, selected, smoothed |
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Term
|
Definition
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Term
|
Definition
| What must be achieved in order to match a plan; Synonyms: reference; |
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|
Term
| Desired altitude (DESALT) |
|
Definition
| A guidance control law parameter, generated by the vertical guidance modes; altitude which controlled altitude is attempting to achieve Typical Units: ft; Dimensions: Length; |
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Term
|
Definition
| A trajectory in space determined by guidance to meet the current mission objectives; |
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Term
|
Definition
| A guidance control law parameter, generated by the longitudinal guidance modes; speed which controlled speed is attempting to achieve Typical Units: ft/s,kt; Dimensions: Length / Time; |
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Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| A piece of equipment, a subsystem; Synonyms: physical device, unit |
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Term
|
Definition
| Digitized Feature Analysis Data |
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Term
|
Definition
|
|
Term
|
Definition
| Distance Measuring Equipment |
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|
Term
|
Definition
| A mathematical relationship to model a discrete function, expressed in terms of other values in the sequence; Difference equations are usually derived from differential equations. Compare: continuous-time equation, differential equation, discrete-time equation, Laplace transform, state-space model, Z transform; in avionics, a difference equation usually models periodic process in terms of past values; See Also: first-order filter, integrator, second-order filter; |
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Term
|
Definition
| A mathematical relationship to model a continuous function, expressed in terms of derivatives; Initial conditions are usually given or implied. In avionics, differential equations are commonly used by systems engineers to model avionics systems. The systems engineer usually converts differential equations to difference equations for specification and implementation in software. In avionics, a differential equation usually models continuous-time phenomenon in terms of time derivatives; Compare: continuous-time equation, difference equation, discrete-time equation, Laplace transform, state-space model, Z transform; See Also: first-order filter, integrator, second-order filter |
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|
Term
| Digital Map Generator (DMG) |
|
Definition
| Digitial equipment that produces map video, and sometimes contains TRN; uses Digital Terrain Elevation Data and Digitized Feature Analysis Data; Displays reconstructed digital map data, aeronautical charts or photographs. The digital map data can be annotated with natural and man-made (point and linear) features as well as threats. A Terrain Referenced Navigation algorithm correlates altitude readings with digital map data to provide position data. |
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|
Term
| Digital Terrain Elevation Data (DTED) |
|
Definition
| On a digitial map, data for elevation of terrain; DTED is usually provided by Defense Mapping Agency; Compare: Digitized Feature Analysis Data; |
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|
Term
| Digitized Feature Analysis Data (DFAD) |
|
Definition
| On a digitial map, data for cultural features such as buildings and roads; DFAD is usually provided by Defense Mapping Agency; Compare: Digital Terrain Elevation Data; |
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|
Term
| Digital Terrain Elevation Data (DTED) |
|
Definition
| On a digitial map, data for elevation of terrain; DTED is usually provided by Defense Mapping Agency; Compare: Digitized Feature Analysis Data; |
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Term
|
Definition
| No units, such as ratios; Synonyms: unitless; |
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|
Term
|
Definition
| Towards a point along the shortest distance; Compare: course |
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Term
|
Definition
|
|
Term
|
Definition
| Time divided into quantized intervals; in avionics, time is usually divived into equal intervals to create a periodic process; Compare: continuous time; |
|
|
Term
|
Definition
| A mathematical relationship to describe a function of time, expressed in terms of discrete time; Compare: continuous-time equation, difference equation, differential equation, Laplace transform, state-space model, Z transform; See Also: first-order filter, unit functions; |
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Term
|
Definition
| Method of measurement dependent on use; Synonyms: range; |
|
|
Term
| Distance Measuring Equipment (DME) |
|
Definition
| Equipment for measuring distance, usually from an aircraft to a ground station; usually part of a Tactical Air Navigation system |
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|
Term
|
Definition
|
|
Term
|
Definition
| Doppler Navigation System |
|
|
Term
|
Definition
| A technique for measuring velocity by radiating and determining frequency shift |
|
|
Term
| Doppler Navigation System (DNS, DPLR) |
|
Definition
| A navigation for measuring velocity by radiating and determining frequency shift; |
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Term
|
Definition
| Doppler navigation system |
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|
Term
|
Definition
|
|
Term
|
Definition
| Force of air against aircraft acting in opposite direction of the airspeed vector projected into horizontal plane; Symbols: D; Typical Units: lbf,kip; Dimensions: Mass * Length / Time-squared; |
|
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Term
|
Definition
| Slow, monotonic change in measured data |
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|
Term
|
Definition
|
|
Term
|
Definition
| Digital Terrain Elevation Data |
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|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
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Definition
| Coordinates referenced to the earth; See Also: east-north-up; Compare: body coordinates, stability coordinates |
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Definition
| Environmental data related to the earth at some point of interest; usually a function of latitude and longitude |
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| A measure of the degree to which the earth is oblate; Symbols: epsilon; |
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| The earth model computes data related to the earth. Most data is a function of position. Standard models are: International, Clarke 1866, Clarke 1880, Everest, Modified Everest, Bessel 1841, Australian National, World Geodetic Survey 1972, World Geodetic Survey 1984, Airy, Hough, South American. |
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| Radius of the earth, function of position, separate radii for longitudinal radius and for lateral radius; See Also: state data; Symbols: rho; Typical Units: ft; Dimensions: Length; |
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Definition
| Gaussian radius of curvature |
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Definition
| Prime radius of curvature |
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Definition
| Meridian radius of curvature |
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Term
| Earth-referenced flight path angle |
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Definition
| Angle in vertical plane of airspeed vector and groundspeed vector; usual definition for flight path angle; Compare: air-mass flight path angle; Symbols: gamma sub T; Typical Units: rad, deg; |
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Term
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Definition
| Total velocity measured with respect to a plane tangent to the earth's surface at the current position; a vector composed of velocity north, velocity east, and vertical velocity; See Also: state data; Symbols: V sub E; Typical Units: kt,ft/s; Dimensions: Length / Time; |
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Definition
| A standard earth coordinate frame and sign convention, where east, north, and up are positive; vertical, or V, is sometimes used in place of up; Synonyms: east-north-vertical; Compare: XYZ; |
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| East-north-vertical (ENV) |
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| An angle in the vertical plane through a longitudinal axis; height above mean sea level, usually of terrain; |
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| Atmospheric data and earth data |
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| Operational status of a piece of equipment consisting of a status indicator and status words; Synonyms: health; |
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Definition
| Difference between desired and measured data; Synonyms: delta; |
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Definition
| Data that is the result of filtering two or more signals; Compare: derived, filtered, measured, raw, selected, smoothed |
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| Four parameters for specifiying quaternions; Symbols: e sub < 1 , 2 , 3 , 4 >,a,b,c,s; |
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| A standard model for computing earth data |
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| A pattern of progressively larger squares (a ``square spiral'') followed for searching the ground from an aircraft; Compare: creeping line search, sector search; |
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| Function to determine values from two or values in a table, when the given value lies outside of the range of the table; usually linear but can be higher order; |
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| A device to alter a signal; software to alter a data steam; See Also: averaging filter, band-pass filter, complementary filter, first-order filter, high-pass filter, hysteresis, Kalman filter, limiter, low-pass filter, rate limiter, second-order filter, smoothing filter, wash-out filter; |
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Term
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Definition
| Function to determine values from two or values in a table, when the given value lies outside of the range of the table; usually linear but can be higher order; |
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Term
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Definition
| Data that is the result of filtering a signal; filtering is usually more sophisticated than smoothing Compare: derived, estimated, measured, raw, selected, smoothed; |
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Term
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Definition
| Function to determine values from two or values in a table, when the given value lies outside of the range of the table; usually linear but can be higher order; |
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Definition
| A pattern of progressively larger squares (a ``square spiral'') followed for searching the ground from an aircraft; Compare: creeping line search, sector search; |
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Term
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Definition
| A filter in which the output follows the input, only more slowly; It is usually implemented in software as a difference equation of period T. The first-order filter is commonly used in avionics to smooth data, and to wash out transients at mode change. It is also used as a low-pass filter. When implementing a second-order filter on normalized variables, such as angles, the discontinuities require special treatment. |
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Definition
| A determination of one's position based on external data, such as a known terrain point |
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Definition
| An airplane, as opposed to a rotory wing / helicopter; |
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Term
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Definition
| A control surface on fixed-wing aircraft, usually mounted to the fore edge of the wings, that extends the wing to provide added lift at low speeds; Compare: slats; Symbols: delta sub F; Typical Units: rad, deg,percent; |
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Term
| Flight control system (FCS) |
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Definition
| A primary flight control system or an automatic flight control system; |
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Term
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Definition
| Controls in a cockpit for flying an aircraft; primary flight controls are wheel, yoke, cyclic, pedals, throttle, and collective; secondary flight controls are flight controls other than primary, such as flaps, slats, stabilizer, and landing gear; |
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Term
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Definition
| System, usually software, that generates stick position cues from state errors - typically three cues:. pitch, roll, and throttle for fixed-wing and longitudinal cyclic, lateral cyclic, and collective for rotory wing; |
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Term
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Definition
| Angle in vertical plane of earthspeed vector and groundspeed vector (usual definition), earth-referenced flight path angle; angle in vertical plane of airspeed vector and groundspeed vector (occasional definition), air-mass flight path angle; Symbols: gamma; Typical Units: rad, deg; |
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Definition
| A predetermined route, possibly including guidance modes, communications, and mission objectives, used by guidance and mission management for moding and planning; Series of navigation reference points, waypoints, and mode commands for navigation, radio navigation, guidance, and flight director |
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| A device to measure the earth's magnetic flux; a compass |
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Definition
| A position update by flying directly over a known point |
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Term
| Forward-Looking Infrared (FLIR) |
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Definition
| Sensor equipment used to supplement AGR, extend the aircraft visual search capability and provide position information for guidance and navigation update capability. Imagery derived from the FLIR sensor is displayed in the cockpit. FLIR pointing can be controlled manually using a tracking handle or automatically by the Mission Computer. FLIR converts a heat image into a video image and determines azimuth, elevation, and sometimes range of a point; Synonyms: Infrared Detecting Set; |
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Term
| Gaussian radius of curvature |
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Definition
| Radius of the earth for the best fitting sphere at a given position; Synonyms: earth radius best sphere; Symbols: rho sub G; Typical Units: ft; Dimensions: Length; |
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Term
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Definition
| Guidance control law parameter |
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Term
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Definition
| Latitude measured with respect to horizontal through mass center of the earth; Compare: astronomical latitude, geodetic latitude; Symbols: Phi sub C; Typical Units: rad, deg; |
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Term
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Definition
| Guidance control law parameter |
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Definition
| Latitude measured with respect to normal to reference ellipsoid; Compare: astronomical latitude, geocentric latitude; Symbols: Phi sub T; Typical Units: rad, deg; |
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Definition
| Accelerometers mounted to a platform which is free to rotate, with gyroscopes to measure rotation and servomotors to maintain a fixed attitude with respect to the earth Compare: strapdown inertial sensor; |
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Term
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Definition
| Angle approach a runway; Symbols: Gamma; Typical Units: rad, deg; |
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Term
| Global Positioning System (GPS) |
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Definition
| A navigation sensor based on satellites; A Global Positioning System (GPS) provides highly accurate navigation data: position, velocity, and time reference. GPS is often aided by the INU, AHRS, and Doppler data. GPS is accurate with four or more properly oriented satellites. Accuracy is degraded with improperly placed satellites or fewer than four satellites visible. GPS-INS is the most accurate of modes listed, with day/night and all weather capability. |
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Term
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Definition
| A basic guidance mode, providing lateral guidance, longitudinal guidance and vertical guidance to climb then to accelerate, while maintaining a wings-level roll; in some implementations (such as SOA), individual axes can be overridden by other modes (for example, longitudinal with G/S SEL and vertical with RALT SEL or BALT SEL) |
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Definition
| Global Positioning System |
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Term
| Gravitational acceleration |
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Definition
| Acceleration caused by the force of gravity; Symbols: g; Typical Units: ft/s-squared,g; Dimensions: Length / Time-squared; |
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Term
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Definition
| Force exerted by gravity; gravity sometimes includes effects of the earth's rotation; gravity is often treated as a constant, but for greater accuracy gravity is a function of latitude, altitude, and the phase of the moon (yes, it's true); Symbols: g; Typical Units: lbf,kip; Dimensions: Mass * Length / Time-squared; |
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Definition
| North according to the map grid. |
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Term
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Definition
| Symbols: nu sub g ; Typical Units: rad, deg; |
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Term
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Definition
| Direction of ground speed vector with respect to true north; Synonyms: true track; Symbols: eta; Typical Units: rad, deg; |
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Term
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Definition
| The speed over the ground; earthspeed projected to a horizontal plane; Symbols: V sub g; Typical Units: kt,ft/s; Dimensions: Length / Time; |
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Term
| Groundspeed select (G/S SEL) |
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Definition
| A basic guidance mode, providing longitudinal guidance to an operator selected groundspeed; |
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Definition
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Term
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Definition
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Term
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Definition
| System, usually software, that determines state errors of desired state minus current state, typically three states: heading, altitude, and speed; |
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Term
| Guidance control law parameter (GCLP) |
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Definition
| One of several parameters for the guidance control laws, generated by individual guidance modes; See Also: altitude error scale factor, altitude integral gain, altitude integral input, altitude integral limit, controlled altitude, controlled speed, course cut limit, crosstrack deviation, crosstrack deviation gain, crosstrack deviation rate, crosstrack deviation rate gain, desired altitude, desired speed, path integral gain, path integral limit, path integral value, reference acceleration, reference acceleration gain, track angle error, track angle error gain, velocity error scale factor; |
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Term
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Definition
| An inertial device for measuring change of attitude (pitch rate, roll rate, and yaw rate); gyroscopes usually consist of a gimbled, rotating mass; gyroscopes are usually included in inertial sensors, such as AHRS and INS; See Also: ring-laser gyro; |
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Definition
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Term
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Definition
| Direction on a compass that aircraft is pointed, measured with respect to true north or magnetic north; Symbols: psi; Typical Units: rad, deg; |
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Definition
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Term
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Definition
| A basic output from guidance to flight director, indicating the difference between actual heading and desired heading; Symbols: DELTA psi; Typical Units: rad, deg; |
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Term
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Definition
| A basic guidance mode, providing lateral guidance to an operator selected heading (magnetic heading or true heading, again, operator selectable); |
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Definition
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Term
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Definition
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Term
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Definition
| A filter that allows frequencies above a cutoff frequency to pass while attenuating frequencies below the cutoff frequency; |
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Term
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Definition
| To maintain some aspect(s) of aircraft state, such as heading, airspeed, altitude, pitch |
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Term
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Definition
| A filter that allows frequencies above a cutoff frequency to pass while attenuating frequencies below the cutoff frequency; |
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Term
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Definition
| A standard model for computing earth data |
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Term
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Definition
| A basic guidance mode, providing lateral guidance and longitudinal guidance to maintain an operator selected north velocity and east velocity; if the selected velocities are zero, then a position is held |
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Definition
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Term
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Definition
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Term
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Definition
| A function in which the algorithm for computing output changes at defined events or thresholds, such that output follows one path as input increases and another path as input decreases; Hysteresis can be formalized: (0) at initialization, select algorithm-0 (1).if event-1 occurs, switch to algorithm-1 (2) if event-2 occurs, switch to algorithm-2 ... (N) if event-n occurs, switch to algorithm-n Frequently in avionics, hysteresis prevents a test from oscillating near the transition point due to noise. Implementation is usually: (0) at initialization, set y = 0 (1) if x sub c + h/2 le x, then set y = 1 (2) if x sub c - h/2 lt x lt x sub c + h/2, then let y retain its value (3) if x le x sub c - h/2, then set y = 0 |
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