The microwave landing system MLS

The International Civil Aviation Organisation (ICAO) guidance material on MLS testing aims at minimising MLS flight testing procedures by relying on extensive ground tests. ICAO Doc 8071 currently recommends that periodic ground tests are performed at six monthly intervals and that flight testing is performed annually. The procedures described in the guidance material should not be considered as the only means of performing commissioning and routine MLS tests. Test methodologies other than those recommended may prove more appropriate for a particular MLS installation or operational procedure. Site modelling techniques provide insight into the locations of regions of anomalous guidance within (and outwith) the MLS coverage volume, and can assist in selecting optimum ground equipment positions to minimise the effect of obstructions on MLS guidance. Although site modelling can assist in predicting the locations of regions of anomalous guidance, flight inspection remains the only means of assessing the magnitude and effects of such anomalies and of providing final assurance that an installed MLS complies with ICAO standards