The Atmosphere — Page 1, Lesson 8

Let’s start at the very beginning of your meteorology syllabus. I’m going to give you the formal definition of the subject itself, then walk through why we study it, and finally show you some real accident data that proves why this matters to you as a professional pilot. First, the definition of meteorology. It is “the branch of science dealing with the earth’s atmosphere and the physical processes occurring in it.” That’s the exact wording you need to know. So meteorology is not just about whether it will rain today; it is the scientific study of the entire envelope of air around our planet and every physical mechanism that happens inside that envelope — heating, cooling, pressure changes, condensation, wind formation, and so on. Now, why do we, as pilots, study this science? The book gives five clear reasons. Let me take them one by one. First, we study meteorology to understand the physical processes in the atmosphere. That is the foundation — if you don’t know how the atmosphere behaves, you cannot predict what it will do next. Second, we study it to understand the meteorological hazards, their effect on aircraft, and how to minimize the risks posed by those hazards. Hazards like turbulence, icing, thunderstorms, wind shear — these are not abstract concepts; they directly affect the safety of every flight you operate. You need to know what they are, how they damage or endanger the aircraft, and what procedures reduce that danger. Third, we study meteorology to identify the weather information that is required for each flight. Not every flight needs the same weather briefing. A short domestic leg in summer has different requirements than a long-haul oceanic crossing in winter. You need to know what to ask for. Fourth, we study it to interpret actual and forecast weather conditions from the documentation provided. You will receive weather charts, reports, and forecasts — METARs, TAFs, SIGMETs, significant weather charts, and so on. This course will teach you to read them correctly. Fifth, we study it to analyse and evaluate weather information before flight and in-flight. That means not just reading the data, but making a judgment: is this weather safe? Is the trend improving or deteriorating And finally, to devise solutions to problems presented by weather conditions. When the weather is marginal or hazardous, you need to be able to come up with a plan — a different route, a hold, an alternate airport, a different altitude. The book then makes a very sobering statement: “Weather is the one factor in modern aviation over which man has no control; a knowledge of meteorology will at least enable the aviator to anticipate some of the difficulties which weather may cause.” That is the core message. We cannot stop a thunderstorm or turn off the wind. But we can anticipate it, avoid it, or prepare for it — and that anticipation comes from knowledge. Now let’s look at the accident data. The book presents a table titled “Weather-influenced Accidents to UK Transport Aircraft” covering the period 1975 to 1994. The table is split into two parts. The first part includes all accidents, including ramp and other minor ground occurrences. The second part excludes those selected ramp and other occurrences to give a clearer picture of operational accidents. Let me walk you through the first part. For all aircraft — aeroplanes and rotorcraft combined — over the full twenty-year period, there were 499 total accidents. Of those, 104 were weather-influenced, which is 20.84 percent. So roughly one in five accidents had weather as a contributing factor. For aeroplanes alone, 430 total accidents, 84 weather-influenced, which is 19.53 percent. For rotorcraft, 69 total, 20 weather-influenced, which is 28.98 percent — a higher proportion. Now look at the trend. In the earliest five-year block, 1975 to 1979, weather-influenced accidents for all aircraft were 34.43 percent. By 1990 to 1994, that percentage dropped to 13.13 percent. But the book adds a note: the 1990-94 figure includes ramp and other minor ground accidents, which pulls the percentage down. That is why the second part of the table is important. In the second part, excluding those minor ground occurrences, the picture changes. For all aircraft over the full period, 367 total accidents, 104 weather-influenced, which is 28.34 percent. For aeroplanes, 298 total, 84 weather-influenced, which is 28.18 percent. For rotorcraft, the same numbers as before because the exclusion only affected aeroplanes: 69 total, 20 weather-influenced, 28.98 percent. Look at the trend in this cleaned-up data. For aeroplanes, 1975-79 was 32.69 percent. 1980-84 was 29.85 percent. 1985-89 was 28.20 percent. 1990-94 was 24.75 percent. So there is a gradual decline, but even in the most recent period, nearly one in four aeroplane accidents was still weather-influenced. That is not a small number. The key takeaway from this data is that weather remains a significant factor in aviation accidents, even as technology and training improve. Your job as a pilot is to understand meteorology well enough to keep yourself and your aircraft out of that 24 to 28 percent. That is the introduction to the subject. Now you know what meteorology is, why we study it, and how much it matters in real accident statistics.