October 6, 2011

Unpacked: Lightning Strikes

Image courtesy of 10154402 on Flickr

Welcome to our new column, Unpacked, where we demystify some of the most provocative topics on the minds of fliers. We’ll unpack a new topic of interest to travelers and lovers of aviation on the first Thursday of each month.

The first edition brings us to one electrifying topic: lightning strikes. You hear about planes getting hit by lightning and maybe you’ve even been on an airplane that was struck. We’re here to explain more about what happens when there’s lightning in our plane’s path and how aircraft and crews are equipped to handle it.

If you’re not already familiar with the science behind these not-so-friendly-but-often-pretty bolts of energy, lightning is simply the discharge of static electricity. We see lightning most frequently during moderate to severe thunderstorms, when horizontal and vertical winds carry droplets of water that get larger the higher up they’re carried. Friction is created as a result of those water drops moving in different directions and colliding with one another and that static has to find somewhere to go. The trapped energy tries to find the path of least resistance to discharge, and with few contenders at 35,000 feet that sometimes ends up being planes.

There are different kinds of lightning – cloud to ground lightning as well as cloud to cloud lightning. It’s the cloud to cloud lightning that more frequently catches a plane in its path. Planes can often avoid potential lightning and the other not-so-fun effects of thunderstorms, which take place in the troposphere (the layer of the atmosphere where weather happens), but some storms are so large that even planes can’t fly above them. Towering thunderstorms can reach as high as 50 or 60,000 feet and can spread out over a large mileage area.

That said, planes are built with thunderstorms and lightning strikes in mind. Our aircraft are certified with equipment built to withstand weather. Planes are in the business of flying in the air after all, and lightning has been happening since way before the Wright Brothers. Our planes, much like tall buildings and other structures, are designed to diffuse lightning and to discharge it without taking a significant beating to its structural integrity.

Aircraft are bonded so that lightning moves along a deliberately-created path along the exterior of the body and exits through the tail or the wingtip. In addition, our planes (like many newer planes built today) are built from composite material and are not purely metal, which makes it a less desirable conductor for lightning. Interwoven mesh or screen-like material inside the plane also helps discharged static to dissipate or further break down the force of the electrical energy that enters the plane, weakening it. Static discharge wicks help direct the energy to exit via chosen points, keeping the lightning far away from harming our important customers and crewmembers. Sometimes you can look out the window and see a ball of energy seemingly dancing on the wings, a phenomenon known as St. Elmo’s Fire (not to be confused with the 1980′s crowd-pleaser starring Emilio Estevez).

The best defense against lightning in general are our weather radar systems. We utilize technology created by MIT and used by the FAA to monitor weather systems in real time, letting us know where we can expect thunderstorms with lightning up to two hours out. Our pilots work closely with Air Traffic Control as well as our Dispatch team to route their trip to avoid any potential icky weather wherever possible. They also have tools on board that help guide them, including a radar antenna in the nose of the plane that can be used to read thunderstorms 20-30 miles out and are in constant communication with en-route centers that are monitoring the weather patterns over their air space.

Lightning strikes are no dull matter but neither are they something to really worry about too much when you’re flying; it’s much like watching a lightning storm from inside a car or your home.

Feel free to leave your thoughts and questions in the below comments section and stay tuned for our next edition of Unpacked coming soon!

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