IntroductionIn aviation, radar system used to detect aircraft, meteorological formations and terrain. The radar system uses radio waves to determine the range, altitude, direction and speed of objects. The primary surveillance radar (PSR) and secondary surveillance radar (SSR) are installed in the ground-based air traffic control (ATC) radar system. The PSR is a radar system that detects the position of aircraft within the control area and weather conditions. The SSR is a radar system that detects the position of the aircraft and receives additional information, such as the identity, altitude and distance of the aircraft. Both PSR and SSR antennas are placed in the same location and function as an integral system. The Raytheon Airport Surveillance Radar (ASR-11) is a National Airspace System (NAS) certified ATC radar system deployed worldwide at more than 125 sites. The radar systema) Functionality of the PSR system is independent surveillance, no additional on-board equipment is needed for detection. The PSR allows the air traffic controller to monitor the aircraft in the airspace, when no aircraft can remain invisible. The PSR only determines the position of the aircraft when the energy beam hits an aircraft and is reflected in the direction from which the reflection comes and in the weather conditions. The position will be sent to the ATC system where it will be displayed by the air traffic controller as a radar signal. The SSR is associated with the PSR and requires the installation of the transponder on board since it is a radio receiver and transmitter that operates on the radar frequency receiving n 1030 MHz and transmit on 1090 MHz. The SSR will send an interrogation signal in 1030 MHz from a continuously rotating antenna to the planes flying in its sector and a plane equipped with a transponder...... middle of paper ......services and procedures", 2 May 2013 http://www.iaa.ie/safe_reg/iaip/Published%20Files/AIP%20Files/ENR/EI_ENR_1_6_EN.pdfFAA, “Section 5. Surveillance Systems,” March 4, 2014 http://www.faa.gov/ air_traffic/publications/atpubs/aim/aim0405.htmlPhil V., "Service Surveillance Systems air traffic" http://www.airwaysmuseum.com/Surveillance.htmFAA, "Airport Surveillance Radar (ASR-11)", January 15, 2014 http://www.faa.gov/air_traffic/technology/asr-11/ Wikipedia, "Controller-Pilot Data Link Communications" http://en.wikipedia.org/wiki/Controller%E2%80%93pilot_data_link_communicationsVatsim uk, "Introducing RADAR" www.vatsim-uk.co.uk/download/fetch/?downloadID=00208Mail Today, "A Radar Failure of 30 Minutes Hits Air Operations at Delhi's IGI Airport", February 9, 2013 http://indiatoday.intoday .in/story/power-outage-igi-airport-leads-to-mass-scare-india-today/1/249546.html