What’s That ‘Whistling Sound’ Before Takeoff?

The whistling sound comes from the Power Transfer Unit (PTU), a hydraulic system inside the aircraft.

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The PTU balances hydraulic pressure between systems, ensuring landing gear, brakes, and flaps work

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Aviation fans call it the “barking dog” sound because of its unusual, whiny tone during operation.

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The whistling PTU sound is most noticeable on Airbus A320 family aircraft, though other models may produce it too.

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Although unusual, the sound is totally normal and means the plane’s hydraulic systems are working correctly.

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Next time you hear that strange whistle before takeoff, you’ll know it’s just the PTU doing its important job.

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Learn fascinating facts about aircraft systems and prepare for a career as cabin crew or ground staff with Skytech Aviation.

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What’s That ‘Whistling Sound’ Before Takeoff?

The whistling sound comes from the Power Transfer Unit (PTU), a hydraulic system inside the aircraft.

It’s Called the PTU

The PTU balances hydraulic pressure between systems, ensuring landing gear, brakes, and flaps work

Why It’s Needed

Aviation fans call it the “barking dog” sound because of its unusual, whiny tone during operation.

Sounds Like a Dog Bark!

The whistling PTU sound is most noticeable on Airbus A320 family aircraft, though other models may produce it too.

More Common on Airbus

Although unusual, the sound is totally normal and means the plane’s hydraulic systems are working correctly.

Perfectly Safe to Hear

Next time you hear that strange whistle before takeoff, you’ll know it’s just the PTU doing its important job.

The Mystery Solved

Learn fascinating facts about aircraft systems and prepare for a career as cabin crew or ground staff with Skytech Aviation.