4/20/23 

Pilot/Controller Glossary 

LOCAL AIRPORT ADVISORY (LAA)

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 A service available only in Alaska and provided by facilities that are 

located on the landing airport, have a discrete ground

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to

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air communication frequency or the tower frequency 

when the tower is closed, automated weather reporting with voice broadcasting, and a continuous ASOS/AWOS 

data display, other continuous direct reading instruments, or manual observations available to the specialist. 

(See AIRPORT ADVISORY AREA.) 

LOCAL TRAFFIC

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 Aircraft operating in the traffic pattern or within sight of the tower, or aircraft known to 

be departing or arriving from flight in local practice areas, or aircraft executing practice instrument approaches 

at the airport. 

(See TRAFFIC PATTERN.) 

LOCALIZER

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 The component of an ILS which provides course guidance to the runway. 

(See INSTRUMENT LANDING SYSTEM.) 
(See ICAO term LOCALIZER COURSE.) 
(Refer to AIM.) 

LOCALIZER COURSE [ICAO]

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 The locus of points, in any given horizontal plane, at which the DDM 

(difference in depth of modulation) is zero. 
LOCALIZER OFFSET

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An angular offset of the localizer aligned within 3

 of the runway alignment. 

LOCALIZER TYPE DIRECTIONAL AID (LDA)

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 A localizer with an angular offset that exceeds 3

 of the 

runway alignment, used for nonprecision instrument approaches with utility and accuracy comparable to a 

localizer, but which are not part of a complete ILS. 

(Refer to AIM.) 

LOCALIZER TYPE DIRECTIONAL AID (LDA) PRECISION RUNWAY MONITOR (PRM) APPROACH

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An approach, which includes a glideslope, used in conjunction with an ILS PRM, RNAV PRM  or GLS PRM 

approach to an adjacent runway to conduct Simultaneous Offset Instrument Approaches (SOIA) to parallel 

runways whose centerlines are separated by less than 3,000 feet and at least 750 feet. NTZ monitoring is required 

to conduct these approaches. 

(See SIMULTANEOUS OFFSET INSTRUMENT APPROACH (SOIA).) 
(Refer to AIM) 

LOCALIZER USABLE DISTANCE

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 The maximum distance from the localizer transmitter at a specified 

altitude, as verified by flight inspection, at which reliable course information is continuously received. 

(Refer to AIM.) 

LOCATOR [ICAO]

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 An LM/MF NDB used as an aid to final approach. 

Note: A locator usually has an average radius of rated coverage of between 18.5 and 46.3 km (10 and 25 NM). 

LONG RANGE NAVIGATION

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(See LORAN.) 

LONGITUDINAL SEPARATION

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 The longitudinal spacing of aircraft at the same altitude by a minimum 

distance expressed in units of time or miles. 

(See SEPARATION.) 
(Refer to AIM.) 

LORAN

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 An electronic navigational system by which hyperbolic lines of position are determined by measuring 

the difference in the time of reception of synchronized pulse signals from two fixed transmitters. Loran A 

operates in the 1750-1950 kHz frequency band. Loran C and D operate in the 100-110 kHz frequency band. In 

2010, the U.S. Coast Guard terminated all U.S. LORAN-C transmissions. 

(Refer to AIM.) 

LOST COMMUNICATIONS

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 Loss of the ability to communicate by radio. Aircraft are sometimes referred to 

as NORDO (No Radio). Standard pilot procedures are specified in 14 CFR Part 91. Radar controllers issue 

PCG L

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