An Air Traffic Control (ATC) demonstration experiment using Engineering Test Satellite V (ETS-V) was conducted to evaluate usefulness to use geostationary satellite in oceanic ATC. In the experiment, the position of aircraft was measured, voice and data communication between ground and aircraft was conducted. The result shows that the positioning accuracy is enough to minimize present separation of aircraft in ocean, and most controllers participated in the experiment evaluate the quality of voice communication through satellite is better than that of present HF Communication. It also shows the possibility to improve oceanic ATC capability with satellite data link.

We have studied the effect of MLS EL (Elevation) antenna on ILS GP (Glide Path) structure by flight experiment and computer simulation.

In this study, we installed a mock-up of EL antenna at various points in front of the GP antenna, and measured the GP structures. And also, GP structures for the similar sitings are calculated by means of GTD (Geometrical Theory of Diffraction).

Both results have shown good coincidence, and we have found that the area where collocation of EL and GP antenna shall conform to the ICAO standards for ILS GP structure, is wider than previously suggested by other papers.

The azimuth and back azimuth ground equipments of Microwave Landing System (MLS) transmit digital data to airbone receiver as well as angle guidance signals. These digital data are classified two different classes by the word length. The 32 bits basic data which describes the performance and status of the MLS ground equipments. This data are used for monitor of the equipments and as parameters for processing the angle guidance signals. The 76 bits auxiliary data which informs to airbone receiver, the equipments siting information and the weather conditions near the runway, etc. The auxiliary data are necessary to provide informations for MLS RNAV approach, e.g., computed center line approach (CCLA) and other advanced operations.

This paper describes current status on SARPs of MLS data functions and flight tests on rate of detection for MLS basic data.

Results obtained here are as follows;

(1) A 95 percent or more rate of detection for the 32 bits basic data is obtained in severe multipath (M/D=-1.7dB) area during all the time of the approach flight.

(2) Remarkable error of detection is observed in diffraction region of the hanger, due to the signal shadowing.

(3) It is estimated by a simulation that the transmitted data are blocked by a large aircraft on taxiway.

These results are expected to give MLS siting criteria, sensitive area for data signals and operational procedures.