Aviation Maintenance Terms beginning with L
Automatic Dependent Surveillance Broadcast (ADS-B)
An advanced surveillance technology where ADS-B OUT equipped aircraft share position, altitude, velocity, and other information with ATC and other appropriately equipped aircraft.
ADS-B IN
Receipt, processing, and display of other aircraft’s ADS-B transmissions. ADS-B IN is necessary to use airborne applications.
ADS-B OUT
Transmission of an aircraft’s position, altitude, velocity, and other information to other aircraft and ATC ground-based surveillance systems.
Automatic Dependent Surveillance - Rebroadcast (ADS-R)
Retransmission of UAT ADS-B messages from aircraft on the 1090ES link and 1090ES messages on the UAT link. ADS-R ensures aircraft equipped with different links can receive messages from one another when equipped with ADS-B IN.
Area Navigation (RNAV)
A method of navigation that permits aircraft operation on any desired flight path within the coverage of station-referenced navigation aids or within the limits of the capability of self-contained aids, or a combination of these.
Barometric Altitude Integrity Code (NICBARO)
Indicates if pressure altitude is provided by a single Gillham encoder or another, more robust altitude source. Because of the potential for an undetected error in a Gillham encoding, many Gillham installations are cross-checked against a second altitude source. NICBARO annotates the status of this cross-check.
Flight Information System - Broadcast (FIS-B)
A ground broadcast service provided over the UAT data link. The FAA FIS-B system provides pilots and flightcrews of properly equipped aircraft with a cockpit display of certain aviation weather and aeronautical information.
Flight Manual
A generic term used throughout this AC to represent the AFM, RFM, AFM supplement, or RFM supplement.
Galileo
A European satellite-based radio navigation system being developed that will provide a global positioning service.
Global Navigation Satellite System (GNSS)
The generic term for a satellite navigation system, such as GPS, that provides autonomous worldwide geo-spatial positioning and may include local or regional augmentations.
Global Positioning System (GPS)
A U.S. satellite-based radio navigation system that provides a global positioning service. The service provided by GPS for civil use is defined in the Global Positioning System Standard Positioning Service Performance Standard, 4th edition, dated September 2008, available at http://www.gps.gov/technical/ps/2008-SPS-performance- standard.pdf.
GNSS Time of Applicability
The time when the position output from the GNSS sensor is applicable.
GNSS Time of Measurement (TOM)
The time when the last GNSS signal used to determine the position arrives at the aircraft GNSS antenna.
Horizontal Figure of Merit (HFOM )
The radius of a circle in the horizontal plane, with its center being at the true position, that describes the region assured to contain the indicated horizontal position with at least 95 percent probability under fault-free conditions at the time of applicability.
Horizontal Protection Level Fault Detection (HPLFD)
The radius of a circle in the horizontal plane, with its center being at the true position, that describes the region assured to contain the indicated horizontal position. HPLFD is a horizontal region where the missed alert and false alert requirements are met for the chosen set of satellites when autonomous fault detection is used. It is a function of the satellite and user geometry and the expected error characteristics; it is not affected by actual measurements. Its value is predictable given reasonable assumptions regarding the expected error characteristics.
Horizontal Protection Level Fault Free (HPLFF)
Fault-free horizontal protection level. Refer to RTCA/DO-229D.
Mode Control Panel
The Mode Control Panel, (MCP) contains controls that allow aircrew to interface with the autopilot system. The MCP can be used to instruct the autopilot to perform tasks such as; hold a specific altitude, change altitudes at a specific rate, hold a specific heading, turn to a new heading, and or follow the directions of a flight management computer. The MCP is not the autopilot, it just controls the mode in which the autopilot operates.
Navigation Accuracy Category for Position (NACP)
Used to indicate, with 95 percent certainty, the accuracy of the aircraft reported horizontal position. A NACP of 8 or greater is required by § 91.227.
Navigational Accuracy Category for Velocity (NACV)
Used to indicate, with 95 percent certainty, the accuracy of the aircraft reported horizontal velocity. A NACV of 1 or greater is required by § 91.227.
Navigation Integrity Category (NIC)
A parameter that specifies an integrity containment radius. A NIC of 7 or greater is required by § 91.227.
Position Source
The on-board avionics equipment that provides the latitude, longitude, geometric altitude, velocity, position and velocity accuracy metrics, and position integrity metric. Additionally, the position source may provide the vertical rate parameters.
Receiver Autonomous Integrity Monitoring (RAIM)
Any algorithm that verifies the integrity of the position output using GPS measurements, or GPS measurements and barometric aiding, is considered a RAIM algorithm. An algorithm that uses additional information (such as a multi-sensor system with inertial reference system) to verify the integrity of the position output may be acceptable as a RAIM equivalent. Within this AC, the term RAIM is a synonym for aircraft-based augmentation system (ABAS) and is used to refer to both RAIM and RAIM-equivalent algorithms.
Satellite-Based Augmentation System (SBAS)
A wide coverage augmentation system in which the user receives augmentation information from a satellite-based transmitter. In the United States, this is referred to as Wide Area Augmentation System (WAAS).
Selective Availability (SA)
A protection technique employed by the Department of Defense that degraded GPS accuracy. Selective availability was discontinued on May 1, 2000.
Source Integrity Level (SIL)
The probability of the reported horizontal position exceeding the radius of containment defined by the NIC without alerting, assuming the avionics has no faults. A SIL of 3 is required by § 91.227.
System Design Assurance (SDA)
The failure condition that the position transmission chain is designed to support. An SDA of 2 or greater is required by § 91.227. Refer to A.2.29 for more information.
Traffic Collision Avoidance System
Collision Avoidance systems which rely on transponder interrogations and replies of other airborne aircraft.
Traffic Collision Avoidance System I
TCAS I is the first generation of collision avoidance technology. TCAS I systems are able to monitor the traffic situation around an aircraft and offer information on the approximate bearing and altitude of other aircraft. It can also generate collision warnings in the form of a "Traffic Advisory" (TA). The TA warns the pilot that another aircraft is in near vicinity, announcing "Traffic, traffic", but does not offer any suggested remedy Traffic Collision Avoidance System II.
TCAS II
The second and current generation of instrument warning TCAS. It offers all the benefits of TCAS I, but also offers the pilot direct, vocalized instructions to avoid danger, known as a "Resolution Advisory" (RA). TCAS II systems coordinate their resolution advisories before issuing commands to the pilots, so that if one aircraft is instructed to descend, the other will typically be told to climb — maximizing the separation between the two aircraft.
Traffic Information Service - Broadcast (TIS-B)
TIS-B is a ground broadcast service provided from an ADS-B ground system network over the UAT and 1090ES links that provides position, velocity, and other information on traffic detected by a secondary surveillance radar, but is not transmitting an ADS-B position.
Total Latency
The total time between when the position is measured by the position source (GNSS TOM for GNSS systems) and when the position is transmitted from the aircraft (ADS-B time of transmission).
Uncompensated Latency
Any latency in the ADS-B system that is not compensated through extrapolation. Uncompensated latency can be represented as the difference between the time of applicability of the broadcast position and the actual time of transmission.
Wide Area Augmentation System (WAAS)
The U.S. implementation of SBAS.
14 CFR
Title 14 of the Code of Federal Regulations
AC
Advisory Circular
ACO
Aircraft Certification Office
ACR
ADS-B Aircraft Operation Compliance Report
ADIRS
Air Data And Inertial Reference System
ADS-B
Automatic Dependent Surveillance - Broadcast
ADS-R
Automatic Dependent Surveillance - Rebroadcast
A/FD
Airport/Facility Directory
AFM
Airplane Flight Manual
AFMS
Airplane Flight Manual Supplement
ANSP
Air Navigation Service Provider
ARP
Aerospace Recommended Practice
ASDE-X
Airport Surface Detection Equipment, Model X
ATC
Air Traffic Control
ATCRBS
Air Traffic Control Radar Beacon System
dB
Decibel
DME
Distance Measuring Equipment
EASA
European Aviation Safety Agency
EMC
Electro Magnetic Compatibility
EMI
Electromagnetic Interference
EPU
Estimated Position Uncertainty
FAA
Federal Aviation Administration
FCU
Flight Control Unit
FHA
Functional Hazard Assessment
FIS-B
Flight Information Services - Broadcast
FMS
Flight Management System
GBAS
Ground Based Augmentation System
GNSS
Global Navigation Satellite System
GNSS/IRS
Global Navigation Satellite System/Inertial Reference System
GPS
Global Positioning System
GVA
Geometric Vertical Accuracy
HAE
Height Above Ellipsoid
HAG
Height Above Geoid
HFOM
Horizontal Figure of Merit
HIL
Horizontal Integrity Level
HPL
Horizontal Protection Level
HUL
Horizontal Uncertainty Level
Hz
Hertz
ICAO
International Civil Aviation Organization
ICA
Instructions for Continued Airworthiness
IFR
Instrument Flight Rules
INS
Inertial Navigation System
IRS
Inertial Reference System
IRU
Inertial Reference Unit
kts
Knots
LPV
Localizer Performance with Vertical Guidance
m/s
Meters per second
MCP
Mode Control Panel
MHz
Megahertz
MOPS
Minimum Operational Performance Standards
MSL
Mean Sea Level
NACP
Navigational Accuracy Category for Position
NACV
Navigational Accuracy Category for Velocity
NAS
National Aerospace System
NIC
Navigational Integrity Category
NICBARO
Barometric Altitude Integrity Code
NM
Nautical Mile
POA
Position Offset Applied
RA
Resolution Advisory
Rc
Radius of containment
RAIM
Receiver Autonomous Integrity Monitoring
RFM
Rotorcraft Flight Manual
RFMS
Rotorcraft Flight Manual Supplement
RVSM
Reduced Vertical Separation Minimum
SA
Selective Availability
SBAS
Satellite-Based Augmentation System
SDA
System Design Assurance
SIL
Source Integrity Level
SILSUPP
SIL Supplement
SIS
Signal-in-Space
SSR
Secondary Surveillance Radar
STC
Supplemental Type Certificate
TC
Type Certificate
TCAS
Traffic Alert and Collision Avoidance System
TCAS
I Traffic Alert and Collision Avoidance System (generation 1)
TCAS
II Traffic Alert and Collision Avoidance System (generation 2)
TIS-B
Traffic Information Service - Broadcast
TOM
Time of Measurement
TSO
Technical Standard Order
TSOA
Technical Standard Order Authorization
UAT
Universal Access Transceiver
UTC
Coordinated Universal Time
VFR
Visual Flight Rules
VFOM
Vertical Figure of Merit
VOR
Very High Frequency Omnidirectional Range
VAPP
Target approach airspeed
VFE
Maximum flap extended speed
VH
Maximum speed in level flight at maximum continuous power
VMO
Maximum operating limit speed
VNE
Never-exceed speed
VS
Stalling speed or the minimum steady flight speed at which the airplane is controllable
VY
Speed for best rate of climb
V2
Takeoff safety speed
WAAS
Wide Area Augmentation System
WGS-84
World Geodetic System 1984
Latency
The time incurred between two particular interfaces. Total latency is the delay between the time of a measurement and the time that the measurement is reported at a particular interface (the latter minus the former). Components of the total latency are elements of the total latency allocated between different interfaces. Each latency component will be specified by naming the interfaces between which it applies.