FCS carries out commissioning, routine and special flight inspections of ILS Localizer, Glide Path, Markers, and approach DME subsystems, applying latest flight inspection technology and precise flight inspection procedures.
FCS D-CFMD and D-CFME flight inspection aircraft employ the highly precise phase continuity DGPS position system, which, combined with further aircraft sensors achieve an absolute position accuracy of 10 cm, allowing flight inspection even in adverse weather conditions. A laser tracker is employed by FCS as an additional sensor for commissioning flight inspections or when GPS DOP conditions are poor.
Once yearly, runway visual approach aids are also checked and assessed simultaneously with ILS inspections.
In order to minimize the disturbance of regular air traffic, FCS carries out ILS flight inspections (required twice yearly) at major hub airports at night.
For the inspection of the ILS, flights must deviate both laterally and horizontally from the published approaches; each runway must be approached a number of times for a calibration. In the process, ILS signals are recorded and evaluated for consistency with the tolerances specified by the ICAO.