Topic 6 future air navigation systems

From the earliest days of man's existence he has been looking for a way to figure out where he was and where he was going. The problem has been around so long that many systems have been developed as scientific knowledge grew and technology advanced. But every system has had fundamental problems.

Early travellers probably marked their trails with piles of stones. When man started to travel the oceans the problem became even worse, because there was no place to pile the stones and no landmarks to refer to.

The only constant reference was the stars. Unfortunately the stars are so far away and of course the measurements can only be made at night – and only on clear nights.

With the aid of modern electronics, a number of solutions have been tried, but all have had their problems. Two such systems are LORAN and DECCA. They are radio based systems that are fairly accurate around coastal areas, but they don't cover the rest of the earth and have never been available in the Southern Hemisphere. They are also subject to electrical interference and geographical variations.

Future Air Navigation Systems (FANS) cover three principal areas: voice and datalinks, global navigation and automatic dependent surveillance.

The US Department of Defence came up with the Global Positioning System or GPS. It is based on a system of 24 satellites orbiting the earth at a very high altitude. In some ways they are like a system of 'man-made stars'. It cost the US Government approximately $12 billion to build. But the system really works.

This constellation of satellites circle the earth at altitudes of 20,187 kilometres, every twelve hours (11 hours 57 minutes) in six orbital planes inclined 55° to the equator. They are high enough that they can avoid the problems encountered by land based systems and they use technology accurate enough to give pinpoint accuracy, anywhere in the world, 24 hours a day.

Topic 7 weather information for the pilot

To avoid hazardous flight conditions, pilot must have a fundamental knowledge of the atmosphere and weather behaviour. Air masses do not always perform as predicted, and weather stations are sometimes spaced rather widely apart; therefore, the pilot must understand weather conditions occurring between the stations as well as the conditions different from those indicated by weather reports.

Moreover, the meteorologist can only predict the weather conditions; the pilot must decide whether his particular flight may be hazardous, considering his type of aircraft and equipment, his own flying ability, experience, and physical limitations.

The pilot should have a general background of weather knowledge plus the following basic information:

1) Sources of weather information available to the pilot.

2) Special knowledge the pilot needs in order to understand the weather terms commonly used.

3) Interpretation of weather maps, flying-weather forecast and other data.

4) Conditions of clouds, wind and weather that are merely inconvenient, those that are dangerous, and those that the pilot can use to advantage.

5) Methods for avoiding dangerous conditions.

For the main United Kingdom and some European airports weather information is broadcast from Heathrow Airport in London. The service is known as ‘Volmet’, derived from the French word ‘Vol’, meaning weather.

Volmet meteorological messages are known as METAR - routine met aerodrome reports. Each broadcast consists of the following details in respect of each airport:

a) Station name; g) Cloud details;

2. Time of observation; h) Temperature;

3. Surface wind details; i) Dew point;

4. Horizontal visibility; j) QNH;

5. Runway visual range; k) Trend.

6. Weather details;