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The evaluation process, using properly equipped aircraft, regarding continuity, integrity and accuracy of significant parameters from radio navigation aids and procedures, aiming their calibration with international standards.
Aircraft navigate. Traditional air navigation uses information given or sent by special dedicated transmitters on ground (called radio-navigation aids). There is a variety of aids’ type, supplying different information (bearing, distance, path deviation…) and, as any other electronic devices, these transmitters may fail, lose strength or accuracy, work out of tolerance or give wrong information, with a prospective impact on airspace safety. This is the reason why a periodical flight service to check, verify and certify their data is needed. This is a Flight Inspection. Aircraft equipped with special and dedicated hardware (called a Flight Inspection System) collect radio-navigation aids’ data and apply (compare with) international standards’ tolerance (this is called calibration), to validate electronic signals in space and certify final status of aids (for it to be published for general knowledge). The goal is having a safe air navigation infrastructure, ensuring the integrity of instrument approaches and airway procedures.
Arturo Cortijo 09:41, 17 June 2009 (UTC)
Flight Inspection Systems 
Flight Inspection Systems are installed in aircraft, and they have dedicated antennas, receivers/transceivers and sensors to collect (usually real-time acquisition) data from navigation aids under inspection. The data received by this equipment are decoded by flight inspection computers and compared with the real aircraft position, which accuracy is essential. This position can be calculated by several devices and techniques (GPS, inertial systems, barometric systems, landmark systems...) or sent to the flight inspection aircraft by external (usually optical) devices. This process results are displayed on operator/inspector workstations, also installed in the aircraft.