Complex sentence: Radio-navigation aids must keep a certain degree of accuracy (given by international standards such as FAA, ICAO, etc); to assure this is the case, flight inspection organizations periodically check critical parameters on properly equipped aircraft to calibrate and certify TLS precision.
Split into simpler sentences: Radio-navigation aids must keep a certain degree of accuracy (given by international standards such as FAA, ICAO, etc). To assure this is the case, flight inspection organizations periodically check critical parameters on properly equipped aircraft to calibrate and certify TLS precision.