Why pilots avoid storms (and what happens if you fly near one)

In brief

• Storms can pose a danger to planes, so pilots do everything they can to avoid flying through or near them
• Pilots get access to detailed forecasts and flight plans are prepared to avoid major storm activity
• Even if your plane is struck by lightning, it’s completely safe!

Why storms can be dangerous to planes, passengers and pilots

Pilots avoid thunderstorms because they are powerful phenomena that could be dangerous to planes. Storm clouds can contain turbulence, hail and lightning. They can also contain strong winds that can rapidly change direction.

While storms may look dramatic they are expected, tracked, and avoided by experienced pilots every day. Before every flight, the route of the plane (the flight plan) is adjusted to avoid storms as much as possible. 

We know many people who are afraid to fly worry about storms, but we’ll show you why storm avoidance is part of everyday airline safety. You’ll learn about the established storm warning system that provides pilots and flight planners information they need to keep your flight safe and smooth.

Understanding thunderstorms

Thunderstorms form when warm, moist air rises quickly into cooler air above, creating huge, towering cumulonimbus clouds that can extend over 30,000 feet. 

Did you know a single bolt of lightning contains a mind-boggling one billion joules of energy? That’s enough to power your home for around 9 days. 

Inside these clouds, air currents move violently up and down, creating powerful updrafts and downdrafts.

These vertical air movements are a key cause of turbulence, and that turbulence can be strong.

As well as strong air movements, heavy rain, hail, icing conditions and electrical activity are all weather conditions around thunderstorms. 

Thunderstorms are a common weather phenomena. You can see the storm activity across the world with this fascinating map.

Thunderstorms can be dangerous to planes which is why pilots will do everything they can to avoid them. They’re supported by a huge amount of technology, including radar, air traffic control, and real time-pilot reports (PIREPs).

The science of avoiding storms

Avoiding bad weather in the air begins long before takeoff on the ground. Before every flight, pilots and flight planners review detailed meteorological reports and radar images to understand where storms might form along their route. 

Pilots and traffic controllers will plan flight paths that avoid storm systems. They’ll often add a margin for flexibility in case conditions change. This margin provides you with extra protection.

Once in the air, pilots have access to a large amount of information to help them. Modern aircraft are fitted with sophisticated weather radar systems that detect rainfall intensity and turbulence ahead. 

On the ground, air traffic control teams and meteorological services provide continuous updates, tracking developing weather patterns and sharing information across aircraft in the same airspace. They’ll have a deep knowledge of potential problems, with turbulent routes well known.

As well as this advanced technology, pilots will have spent many thousands of hours in the sky and can use their eyesight and experience to identify problem clouds and avoid them. 

Pilots can avoid storms by flying around them, or they might climb above a developing cell or descend slightly to pass below the worst of the weather. These changes are made calmly, well in advance, and often without passengers noticing anything at all.

Why pilots never fly through thunderstorms

Thunderstorms pose a risk of severe turbulence, hail damage, lightning strikes, and sudden wind changes that can be dangerous. Even several miles from the centre, you can find unstable air and strong gusts. 

Pilots will always maintain generous distances (20 miles or more) from large storm systems. This ensures that the aircraft flies through calm, predictable air.

What happens if a plane flies near a storm

Of course, even with the advanced forecasting technologies, sometimes a plane will pass near the edges of thunderstorms. When that happens, passengers might experience turbulence.

Pilots are trained to handle turbulence and will act if they feel the need to. They may seek a smoother altitude or adjust course. 

In some cases, this may not be possible, so they may adjust the plane’s speed to what’s known as “turbulence penetration speed”. This allows the aircraft to move flexibly with the air rather than resisting it. 

If you experience storm-related turbulence on a flight, it’s likely the seatbelt sign will come on. Cabin crew will secure the cabin and ask passengers to remain seated, while the pilots focus on safely flying the plane. (You can learn more about what happens during turbulence in the guide.)

In most cases, storm turbulence won’t last very long and you’ll soon be through it and flying calmly and smoothly again.

What if lightning strikes a plane?

Seeing lightning outside your window can be a little scary for even the most experienced flyers, but it’s rarely dangerous. Aircraft are struck by lightning on average once every 1,000 flight hours, but it’s not a safety issue.

The outer skin of the aircraft acts as a conductor, allowing the electrical charge to pass harmlessly along its surface before exiting through the tail or wingtips. (It’s called a Faraday cage and provides protection for passengers and pilots.)

All commercial aircraft are designed and tested to withstand lightning strikes without damage to essential systems. 

What’s it like being in a plane hit by lightning? There’s usually a brief flash of light and, occasionally, a faint sound. That’s it.

Why passengers can trust the storm-avoidance process

For pilots, avoiding storms is part of the job. They’re operating as a key part of an established and effective process. 

Every decision is guided by safety, and every commercial aircraft operates within strict rules designed to prevent encounters with severe weather. 

At 30,000, a storm outside the window may look dramatic, but it’s likely to be at least 20 miles away. Your pilot will be aware of it and do everything they can to avoid it. 

Safety always comes first

Avoiding thunderstorms isn’t a challenge for pilots, it’s a daily part of the job.

You can relax and know that advanced technology, constant communication, and rigorous training mean your flight will be as safe and smooth as possible.

If you’re worried about storms, turbulence, take off or landing, visit the Help Desk and download the Calm Flight Toolkit.

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