Thunderstorms — Page 257, Lesson 211

I want to walk you through the thunderstorm section of your meteorology syllabus, starting with how these storms affect aerodrome operations and the critical flying techniques you need to know. Let's begin with Aerodrome Warnings. The Meteorological Office issues these for terminal area operations when there is a forecast likelihood of thunderstorms in the immediate vicinity of an aerodrome. "Immediate vicinity" means close enough to directly impact take-off, landing, or ground operations at that specific airfield. Now, there's an important distinction here regarding windshear warnings. At some aerodromes — notably London Heathrow and Belfast Aldergrove — separate windshear warnings may be issued when a nearby thunderstorm is the specific criteria that triggers that warning. But elsewhere, just because a thunderstorm is in the proximity does not necessarily result in a windshear warning being issued. And here's the critical point: the probability of windshear is no less just because no formal warning has been issued. The hazard is still there. In relation to windshear hazards at low-level, your attention is drawn to AIC 84/2008 (Pink 150) — that's an Aeronautical Information Circular, specifically the one titled 'Low Altitude Windshear'. That document contains the detailed guidance you should be familiar with. Moving on to Special Aircraft Observations and the SIGMET service — these are covered in the UK Aeronautical Information Publication. The criteria for Special Aircraft Observations are at GEN 3.5 paragraph 6.2, and the SIGMET service details are at GEN 3.5 paragraph 8. SIGMETs are warnings of significant meteorological conditions that could affect aircraft safety, and Special Aircraft Observations are reports made by pilots when they encounter certain conditions. Now we come to the most important part — Procedures and Flying Techniques. I want you to hear this clearly because it's the foundational advice that overrides everything else. Gathered from research and operational experience, the first and most basic advice for all pilots is this: Do not treat thunderstorms lightly and whenever possible AVOID them. That's not a suggestion — that's the primary directive. Thunderstorms should be avoided either visually — meaning you see them and steer clear — by the use of radar, or by other methods. If avoidance cannot be achieved, and in the absence of specific aircraft flight manual or operations manual guidance for your particular aircraft, then the following procedures and techniques are recommended. If you find it necessary to penetrate an area of cloud which may contain cumulonimbus clouds — and I want to stress this is a last resort — the first action is: Ensure that crew members' safety belts or harnesses are firmly fastened and secure any loose articles beforehand. Switch on the seat belt notices and make sure that all passengers are securely strapped in and that loose equipment — for example cabin trolleys and galley containers — are firmly secured. Pilots should remember... and we'll continue from there.