A study on the instrumentation landing system at Luqa Airport, Malta

Abstract

The Instrumentation Landing System on the new runway at Luqa Airport is an American system and is of Category II. A Category II system provides guidance to incoming aircrafts from coverage which is normally between 17 to 25 nautical miles, until 15 metres or less of height above ground. The guidance of this system is provided by two types of radiation. One is provided by the localiser equipment, producing horizontally-polarised radiation, and the other, by the glide slope equipment producing vertically-polarised radiation. These two radiations are transmitted at 90° to each other. Hence, if this radiation could be seen visually from the approaching end, the form of Cartesian axes ore observed. Thus, since this radiation cannot be seen, receivers are provided to identify its characteristics. One characteristic of this radiation is […] zero difference in depth of modulation (D.D.M.) at the centre, while moving away from the centre will increase the D.D.M. Ideally, the way of approach is a D.D.M. of zero, since the zero D.D.M. is adjusted to the centreline of the runway. If the zero D.D.M. position cannot be retained, a maximum D.D.M. of .155 will still guide the aircraft to the runway. The D.D.M. reading is not denoted positively or negatively to indicate on which side of the centreline the aircraft is. Hence, another characteristic of this radiation is that, to the left of the centreline, there occurs a predominance of the 90 Hz modulating tone, and to the right, a predominance of 150 Hz modulating tone. These ore indicated by front panel lamps. In Chapter I, there is presented the requirements for such a system to be built and installed. These requirements are established under international recognition by the International Civil Aviation Organisation. Chapter II indulges in the function and operation of the transmitter, monitor and antenna array. In this Chapter, only the localiser is considered, becouse it is identical to the glide slope equipment. The monitoring equipment is provided to keep a continuous check on the system. This check is done by analysing all parameters on which the characteristics depend. If any of the parameters are out of tolerance, a standby system will come in, and on alarm is sent to the control tower. In Chapter III, on addition to the system is being proposed. What is boing proposed is a velocity measuring device, which uses the marker beacons as references. In the Appendix of this study, there are defined some technical terms used for aviation purposes, which will come in use, while reading this presentation.