How often do planes really get struck by lightning?
A domestic flight leaving Chicago was reported to have been diverted after being struck by lightning while in flight last week. Soon after that announcement, my social media feed was peppered with a supposed photo of the incident—an impressive lightning bolt passing through a jet passenger plane. Except the photo showed a plane on the tarmac, not inflight, and from a different airline. A little investigating showed the photo was actually two-years-old.
No injuries were reported and, after a thorough inspection, last week’s flight was allowed to continue on its way. Were those passengers just really lucky? Or is lightning striking a plane not such a big deal? How often to planes get struck by lightning and what kept those passengers safe?
What is lightning?
Lightning can occur when particles in a storm cloud collide and break apart while picking up an electrostatic charge. Positively charged particles, which are lighter, will accumulate toward the top of the cloud, while heavier, negatively charged particles sink toward the bottom. This voltage difference is thought to inspire an electrostatic discharge or a spark of electricity which can occur between the different regions of the cloud itself, from cloud to cloud, or from the cloud to the ground.
The National Severe Storms Laboratory estimates that a bolt of lightning can have between 100 million to 1 billion volts and contain billions of Watts of energy. That energy can heat the air to temperatures from 18,000 to 60,000 degrees Fahrenheit. So how often does a plane get in the path of one of these impressive bolts?
How often do planes get struck by lightning?
There are actually many, many reports of planes being struck by lightning. (One of my favorite headlines was “Terror at 2,000 Feet,” which maximizes the drama.) And while the intensity of lightning—not to mention the booming thunder it tends to associate with - does come with a flare for the dramatic, lightning striking a plane is actually a fairly ordinary occurrence.
The Federal Aviation Administration estimates that commercial jet airliners in the US are struck by lightning once every 1,000 flight hours, or once each year, on average. Planes can even trigger lightning themselves by flying through ionized clouds.
However, the last plane crash reported by the National Transportation Safety Board to have occurred due to an encounter with lightning was in 1963 when the fuel tank of the Pan American Boeing 707 was struck by lightning causing an explosion.
If there have been thousands of lightning strikes since then, what keeps passengers safe?