Important Terms and Definitions for JE-ATC Interview

In this article, which is aimed at preparing for JE-ATC Interview, I will first give some basic definitions that you must know before appearing in the ATC Interview. These are general terms ATC guys encounter in day-to-day business like what is Aircraft? What is a Runway or Taxiway? How do they define Flight levels in the sky?

Once this definition part is done then I will focus on Communication, Navigation, and Surveillance Systems that are very essential for the safe conduct of flight in all phases of a flight. These systems make it possible to monitor and guide so many aircraft in the sky or ground at any given time.

Definitions:

• Aerodrome: In aviation, an airport is usually called an Aerodrome. It is a defined area on land or water (including any buildings, installations, and equipment) intended to be used either wholly or in part for the arrival, departure, and surface movement of aircraft.

• Aircraft: Any machine that can derive support in the atmosphere from the reactions of the air other than the reactions of the air against the earth’s surface.

• Runway: A defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft.

• Taxiway: A defined path on a land aerodrome established for the taxiing of aircraft and intended to provide a link between one part of the aerodrome and another.

• Elevation: The vertical distance of a point or a level, on or affixed to the surface of the earth, measured from mean sea level.

• Flight Level: A surface of constant atmospheric pressure which is related to a specific pressure datum, 1 013.2 hecto-pascals (hPa), and is separated from other such surfaces by specific pressure intervals.

• Track. The projection on the earth’s surface of the path of an aircraft, the direction of which path at any point is usually expressed in degrees from North (true, magnetic, or grid)

Communication, Navigation, and Surveillance Systems used in ATC:

• Radar: A radio detection device that provides information on the range, azimuth, and/or elevation of objects.

• Primary Surveillance Radar (PSR): A surveillance radar system that uses reflected radio signals.

• Secondary Radar: A radar system wherein a radio signal transmitted from the radar station initiates the transmission of a radio signal from another station.

• Secondary Surveillance Radar (SSR): SSR is a surveillance radar system that uses transmitters/receivers (interrogators) and transponders.

• CPDLC: The CPDLC (Controller-Pilot Data Link Communication) application provides a means of communication between the controller and pilot, using data links for ATC communication.

• VOR: VHF Omni Directional Radio Range (VOR) is a type of short-range radio navigation system for aircraft, enabling aircraft with a receiving unit to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons.

• ILS: Instrument Landing System (ILS) enables aircraft to land if the pilots are unable to establish visual contact with the runway. It does this by way of transmitted radio signals.

• Localizer: The Localizer is used to provide horizontal guidance to the Pilot. It indicates how far off its optimal path of descent is along the axis of the runway.

• Glide Slope: It provides vertical guidance to the Pilot. The glide slope indicator ensures that the aircraft is following the glide path to remain above obstructions and reach the runway at the proper touchdown point.

• DME: Distance Measuring Equipment (DME) is a transponder-based radio navigation technology that provides pilots with a slant range measurement of the distance to the runway in nautical miles.

• Marker Beacon: A marker beacon is a particular type of VHF radio beacon used in aviation, usually in conjunction with an instrument landing system(ILS), to give pilots a means to determine position along an established route to a destination such as a runway.
a) Outer marker: The Outer Marker is situated on the same course/track as the localizer and the runway center-line, four to seven nautical miles before the runway threshold.
b) Middle marker: A middle marker works on the same principle as an outer marker. It is normally positioned 0.5 to 0.8 nautical miles (1 km) before the runway threshold.
c) Inner marker: Similar to the outer and middle markers; located at the beginning (threshold) of the runway on some ILS approach systems.

• GNSS: A satellite navigation system with global coverage may be termed a global navigation satellite system (GNSS). GNSS is used to pinpoint the geographic location of a user’s receiver anywhere in the world.

• GBAS: Ground-Based Augmentation System (GBAS) is a safety-critical system that augments the GNSS Standard Positioning Service (SPS) by differential corrections and integrity monitoring and provides enhanced levels of service.

• SBAS: Satellite-Based augmentation system (SBAS) is a system that supports wide-area or regional augmentation through the use of additional satellite-broadcast messages.

• GPS: Global Positioning System (GPS) is a space-based navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.

• ADS-B: Automatic Dependent Surveillance-Broadcast (ADS–B) is a cooperative surveillance technology in which an aircraft determines its position via satellite navigation. The information can be received by air traffic control ground stations as a replacement for secondary radar. It can also be received by other aircraft to provide situational awareness and allow self-separation. ADS–B is “automatic” in that it requires no pilot or external input. It is “dependent” in that it depends on data from the aircraft’s navigation system.

• ACAS: Airborne Collision Avoidance System (ACAS) is also known as TCAS (Traffic Collision Avoidance System). TCAS/ACAS is an aircraft system that works on the basis of Secondary Surveillance Radar (SSR) transponder signals that work independently of ground-based equipment. It provides advice to the pilot on potential conflicting aircraft that are equipped with SSR transponders.

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Reference: ICAO DOC 4444.

Also Read – How To Prepare For ATC Exam