Electrically-charged airplanes could avoid lightning strikes

Lightning laboratory test on model aircraft
Lightning laboratory test on model aircraft(Credit: MIT/Joan Montanya/Polytechnic University of Catalonia)

Thunderstorms are something air pilots prefer to avoid, but nonetheless it is estimated that every commercial aircraft is struck by lightning once a year. While this statistic isn't as alarming as it seems, engineers from MIT, under the sponsorship of Boeing, are looking to bring the numbers down by electrically charging airplanes to make them less attractive to lightning.

When large commercial aircraft encounter lightning strikes (which are often triggered by the plane itself) it may result in an alarming flash and bang, but very little damage usually occurs. In fact, the last airplane crash in the United States due to lightning occurred in 1967 when a strike caused a catastrophic fuel explosion.

The reason lightning strikes, while dramatic, cause so little damage is because a conventional aircraft with an aluminum alloy hull is basically a flying Faraday cage. That is, a hollow metal cylinder that's impervious to static electrical fields.

When an airplane is in the vicinity of an electrical storm, its hull develops an electrical charge, which polarizes it. One end of the plane develops a negative charge and the other a positive charge. When this charge becomes strong enough, it generates positive leaders. That is, a highly conductive flow of plasma, which is the preceding stage to a lightning strike. These leaders can close the circuit between electrically charged clouds and the ground, and a bolt of lighting passes through the plane carrying up to 300,000 amps at a billion volts.