What does this sound on a plane mean? The passenger even crossed himself

“Can someone explain what this sound is?” anil_lobo, a tourist from Dubai, asked TikTok users. In his video, he made a comedic over-the-top reaction to a sound that sounds like something on a plane breaking or shifting. Because the sound is repetitive, it sounds like “barking” or loud windshield wipers. There was no reason to worry.

Strange sound on airplanes

This sound can be heard in older Airbus models (they are found in the Wizz Air fleet, among others) and if you have flown on one, you have probably wondered what it was all about.

The sound is caused by the hydraulic system of the aircraft, specifically the PTU (Power Transfer Unit) pump. This is a device that transfers hydraulic power from one of the aircraft's hydraulic systems to another. In short, it is about balancing the pressures between the two systems. Since the system operates in a vacuum, the sound is clear - informs the portal airnavradar.com.

The sound can often be heard on the ground as the engine starts and stops. The PTU's location on the wing means that people sitting in the middle of the plane can hear it more clearly.

New Airbus models in Poland

It is worth noting that the “barking” mainly affects older A320 and A330 models. It is unlikely that we will hear it on the newer A320 and A31 neo aircraft. The Points Guy explains that Airbus has developed a solution to reduce noise on its next-generation single-aisle family of aircraft.

Newer versions already account for 65 percent of Wizz Air's operations , and from December 2025, a second Airbus A321neo aircraft will be based in Wrocław.

Even more modern Airbus models will join the PLL LOT fleet in the years 2027-2031. The Polish carrier will order 40 Airbus A220 aircraft in the -100 and -300 versions. In addition, under the option and purchase right, it will be able to purchase another 44 machines from this manufacturer.

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