Home Airlines Why Are There Spirals Painted On Planes’ Jet Engines?

Why Are There Spirals Painted On Planes’ Jet Engines?

by SharonKurheg

If you’ve ever traveled on a plane and gotten the chance to look at any of the jet engines, you may have noticed a white spiral painted in the center. I had an idea of why it might be there, but I wasn’t sure, so I did some research. Here’s what I found out…

I found out that I was right! 😉

According to KLM’s Renee Penris:

“The spiral has a fairly straightforward function, alerting ground staff to a running engine and ensuring that no one comes too close to it. If an engine is running, you see a white blur or a hypnotizing swirl, depending on the rotation speed of the engine. This visual cue is extremely clear and warns everyone on the apron to stay away from the huge jet engines.”

Spirals come in all different shapes and sizes, and some aren’t even spiral-shaped!

Screen Shot 2019-12-09 at 11.23.51 PM.png

PC: Wikimedia

But regardless of shape, the function is the same – to alert the ground crew that the engine is running and to steer clear, so you don’t get into a situation like this guy:

BTW, you may read in some online entities that the spirals also help alert birds. That started in the 1980s when Rolls-Royce, who builds jet engines, said in a press release, “In-flight these swirls flicker as the engine rotates at high speed, scaring birds and allowing them to fly clear of the engine.”

Yeah, that’s probably not true.

Boeing had an article that was co-written by a researcher and pilot who disagreed and said that birds tend to steer clear from airplanes because of aerodynamics and, well, they hear the engine noise and it usually scares them away (except when it doesn’t. That’s why airports do stuff like this). So they supposedly avoid planes in general before even seeing the ‘flickering’ spirals on the engines.

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This post first appeared on Your Mileage May Vary


steve December 10, 2019 - 5:08 pm

The spiral is not a sure way to know if the engine is running or even preparing to start because you have to look it head on. The best indicator that the aircraft is moving, preparing to move, have engines running or preparing to start engines is by the anti-collision lights. Airliners have a red flashing anti-collision light on the top and bottom of the fuselage and are visible from 360 degrees. If they are on, you need to be aware of aircraft movement or engines running or starting.

Christian December 10, 2019 - 6:27 pm

“Yeah, that’s probably not true.” – A perfect response.


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