Pilot/Controller Glossary Pilot/Controller Glossary  8/15/19 12/31/20  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- The maxi- mum 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]- 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- (See LORAN.)  LONGITUDINAL SEPARATION- The longitudi- nal spacing of aircraft at the same altitude by a  minimum distance expressed in units of time or  miles.  (See SEPARATION.)  (Refer to AIM.)  LORAN- 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 transmit- ters. 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- 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 procedures for pilots to follow in the  event of lost communications during a radar approach  when weather reports indicate that an aircraft will  likely encounter IFR weather conditions during the  approach.  (Refer to 14 CFR Part 91.)  (Refer to AIM.)  LOST LINK (LL)- An interruption or loss of the  control link, or when the pilot is unable to effect  control of the aircraft and, as a result, the UA will  perform a predictable or planned maneuver. Loss of  command and control link between the Control  Station and the aircraft. There are two types of links:  a.  An uplink which transmits command instruc- tions to the aircraft, and  b.  A downlink which transmits the status of the  aircraft and provides situational awareness to the  pilot.  LOST LINK PROCEDURE- Preprogrammed or  predetermined mitigations to ensure the continued  safe operation of the UA in the event of a lost link  (LL). In the event positive link cannot be established,  flight termination must be implemented.  LOW ALTITUDE AIRWAY STRUCTURE- The  network of airways serving aircraft operations up to  but not including 18,000 feet MSL.  (See AIRWAY.)  (Refer to AIM.)  LOW ALTITUDE ALERT, CHECK YOUR ALTI- TUDE IMMEDIATELY- (See SAFETY ALERT.)  LOW APPROACH- An approach over an airport or  runway following an instrument approach or a VFR  approach including the go-around maneuver where  the pilot intentionally does not make contact with the  runway.  (Refer to AIM.)  LOW FREQUENCY (LF)- The frequency band  between 30 and 300 kHz.  (Refer to AIM.)  LOCALIZER PERFORMANCE WITH VERTI- CAL GUIDANCE (LPV)- A type of approach with  vertical guidance (APV) based on WAAS, published  on RNAV (GPS) approach charts. This procedure  takes advantage of the precise lateral guidance  available from WAAS. The minima is published as a  decision altitude (DA).  PCG L-3  LUAW- (See LINE UP AND WAIT.) 