ILS system configuration

Various Landing Aids in Aviation

Various Landing Aids in Aviation

Landing aids can be Any flashing light, radio beacon, communicating device or radar device or any system of such devices for helping aircraft in an approach and landing.

Used to guide a pilot to the runway , helps the pilot to judge his alignment  with the runway and correct angle of approach

Various landing aids

  • Instruments landing system (ILS)
  • Precision approach radar (PAR) or ground approach control (GAC)
  • Airport surveillance radar (ASR)
  • Airport surface detection equipment (ASDE)
  • Approach lights

Instruments landing system (ILS)

ILS system configuration
ILS system configuration

Instrument landing system (ILS) was the only ground-based system certified to provide both lateral and vertical guidance to aircraft on approach to an airport. An ILS system consists of two radio transmitters located on the airport. One radio beam is called the localizer and the other the glide slope. The localizer indicates to pilots whether they are left or right of the correct alignment for approach to the runway and the glide slope indicates the correct angle of descent to the runway.

ILS system provides facilities for landing under conditions of poor visibility. ICAO has divided the visibility into three categories for ILS approach:Instruments landing system

Precision approach radar (PAR) or ground approach control (GAC)

Same as ILS but the information reaches the pilot through his hearing aid. PAR gives to the controller picture of descending aircraft both in plan and elevation then controller checks the alignment and glide slope of aircraft. So no need of navigational

Precision approach radar (PAR) or ground approach control
Precision approach radar (PAR) or ground approach control

equipment. Used for military aircrafts.

Airport surveillance radar (ASR)

ASR provide air traffic controllers with a visual display of the position of each aircraft within the air space surrounding the terminal. Effective up to a distance 50 km to 100 km. It does not indicate the altitude of the aircraft. In INDIA this is provided at Jawahar lal Nehru (Mumbai) and Subhash chandra bose (Calcutta) airports.

Airport surface detection equipment  (ASDE)

ASDE is a short range radar which gives to the controller a pictorial display of the runways , taxiways , terminal areas and shows the position of the aircrafts. ASDE is very efficient in poor visibility to regulate the traffic on the airport. ASDE is able to determine the position and identification of aircraft and vehicles on the airport surfaces, as well as of aircraft flying within 8 km of the airport.

Approach lights system (ALS)

ALS is a lighting system installed on the approach end of an airport runway and consisting of a series of light bars, strobe lights, or a combination of the two that extends outward from the runway end. Approach lighting systems (ALS) are designed

specifically to provide guidance for aircraft approaching a particular runway under nighttime or other low-visibility conditions. The Calvert system was the first approach lighting system to be certified by ICAO, and is also commonly known as the ICAO category I approach lighting system.

Day and Night Landing Aids
Day and Night Landing Aids

The ALS currently certified by the FAA for installation  in the United States consist of a high-intensity ALS with sequenced flashing lights (ALSF). This is required for category II and category III. High-intensity approach lighting system is consist of Sequenced flashing lights (ALSF-1) . Three medium-intensity ALSs (MALSR, MALS, MALSF).