Scientists have accidentally uncovered a surprising behavior in commercial airplanes: they emit radio waves when they release built-up static electricity.
This discovery, made by an international research team led by Professor Olaf Scholten from the University of Groningen, could offer new insights for aviation safety.
Their findings were published on November 26 in Nature Communications.
Static electricity is something we all experience, like when clothes rub against a chair. Airplanes also collect static charge, especially when flying through icy clouds.
Normally, this is not dangerous because airplanes are designed with tiny devices called discharge wicks that safely release the charge without creating sparks or interfering with communication systems.
However, when Scholten and his team used the LOFAR radio telescope system to study lightning, they noticed something unexpected.
While a commercial plane was flying 8 kilometers above the ground, LOFAR detected bursts of radio waves coming not from the usual discharge wicks, but from areas around the aircraft’s two engines and from a single spot on its tail. One tail discharge was pinpointed with remarkable accuracy—within just 50 centimeters.
This unexpected signal was found through the Low-Frequency Array (LOFAR), a network of thousands of simple radio antennas spread across the Netherlands and several other European countries.
LOFAR is normally used to study cosmic phenomena and to take highly detailed images of lightning. In fact, Scholten’s team previously used LOFAR to create the world’s sharpest lightning images.
Because the airplane discharge appeared in the data by chance while the researchers were examining lightning activity, the discovery was completely serendipitous. But it turned out to be extremely useful. By recognizing patterns in the airplane’s radio emissions, the scientists were able to identify and correct a previously unnoticed flaw in their imaging technique. This will make future lightning studies even more precise.
The plane observed in the study was identified using flight tracking data as a KLM Boeing 777-306 (ER). After digging through their records, the researchers found similar emissions from another aircraft flying at an altitude of 11.6 kilometers. Again, the radio waves came from the areas around the engines and one point on the tail. This suggests that aircraft regularly build up and release static charges in specific places, which LOFAR can detect from the ground.
Professor Scholten notes that this information could be valuable for the aviation industry. Static electricity can sometimes cause sparks, which may lead to minor damage on the aircraft exterior. Understanding where and how charge builds up could help engineers design safer and more efficient ways to discharge it.
What started as a simple lightning study unexpectedly opened a new window into how airplanes interact with the atmosphere—revealing invisible electrical events happening high above our heads.
