Did you know? There’s an average of 2,000 thunderstorms in progress at any time around the world. That adds up to millions of thunderstorms every year! Because these powerful storms tend to occur more often in the spring and summer months, now is a good time for a refresher on safe flying during thunderstorm season. Here are a few helpful reminders:
Recall the recipe for a thunderstorm
All pilots should know the three ingredients needed for a thunderstorm to form: moisture, instability, and a lifting action. On a hot summer day, the sun heats the surface of the earth and warms the air above it. When this air is forced upward by a lifting mechanism, it will rise, because warm air is less dense than the cold air surrounding it. This creates instability. As it rises, the warm air transfers heat to the upper level of the atmosphere, in a process called convection. As the water vapor the air contains starts to cool down, it condenses into water droplets and forms cumulus clouds, which will continue to grow as long as warm air from the earth’s surface keeps rising. Then, as cool, dry air flows downward through the cloud (called a downdraft), it pulls water downward as rain. This powerful cycling of updrafts and downdrafts is called a thunderstorm cell.
Know before you go
Be sure you have up-to-date, accurate weather briefings before every flight. Thunderstorms can form rapidly, so if convective activity is forecast, be sure you have an alternate route planned. Using an app such as ForeFlight can help you monitor the weather in real time and avoid getting caught in a storm.
Keep your distance
The FAA recommends staying at least 5 miles away from any visible storm cloud during flight. However, they strongly suggest staying even further away – 20 miles or more – because hail and violent turbulence can occur anywhere within a 20-mile radius of a strong storm. If you do encounter a thunderstorm in flight, stay calm. Slow to your aircraft manufacturer’s recommended airspeed for turbulence and focus on keeping the wings level. Never attempt to fly through a storm, and don’t attempt to fly underneath a storm cloud, even if visibility is good. Remember, thunderstorms are a weather hazard that shouldn’t be taken lightly. Don’t wait until the last minute to detour, and always give storms a wide berth. Thunderstorms and airplanes don’t mix.
Communication is key
Air Traffic Control (ATC) and pilots work together to keep the skies safe for everyone. While ATC can provide weather updates and radar navigation guidance when requested by the pilot, these are secondary duties for a controller. As the pilot in command, it’s ultimately your responsibility to avoid flying into a thunderstorm. Communicate with ATC promptly if you are headed toward a storm and request a deviation early. Don’t assume that the controller knows about the weather at your location and will provide a deviation: ask for one.
Give a report
PIREPs are an invaluable source of information, especially when inclement weather is imminent. Pay attention to pilot chatter and don’t hesitate to volunteer a PIREP of your own flight conditions. Report on things like visibility, turbulence, lightning, clouds, and precipitation intensity.
Trust your gut
When preparing for a flight, use your best judgment and avoid letting “get-home-itis” get the best of you. If you know stormy weather is coming and you cannot plan an alternate route, stay on the ground. There will always be another day to fly!