Unpacked: Sights And Sounds On An Airplane


Welcome to Unpacked, where we demystify hot topics in the airline industry! This time we’re talking about some of the mysterious noises you may have heard on a plane.

Whether you’re a first time flier or a world traveler, we know an unexplained noise or event can cause a little bit of anxiety. To help, we decided to share a few of the more common sights and sounds of a flight in a handy list:

    • Visible condensation in the cabin
      Prior to take off, or while deplaning, you may see vents above the windows pushing out a thick mist. This isn’t smoke, but rather a natural condensation that often occurs when the cool dry air from our air conditioning mixes with the warm humid air from the cabin.

    • Barking/sawing sound
      Have you ever heard what sounded like barking dogs or sawing timber as you settle into your seat prior to departure?  Common guesses as to the source of this sound include changing tires, loading an angry dog or starting an engine. Good guesses, but none of these are correct. That barking sound you hear on the ground is the power transfer unit, which equalizes hydraulic pressure between the engines after a single engine taxi (moving on the ground utilizing only one engine, which is a great way to save fuel, and costs, for everyone).

    • Flexing or bending wings
      Watching out the window, it may be daunting to see the tips of the wings bounce up and down, but did you know they’re designed to bend? Similar to the way some buildings are designed to sway to withstand earthquakes, you want a certain amount of flexibility to your wings to handle turbulence.

    • Moving parts on the wings
      Don’t worry, those parts are meant to move! These parts — the flaps and ailerons — are designed to move and direct air movement in different ways. Flaps (which move out and down) are lifting devices that allow the aircraft to fly at lower air speeds. Ailerons (which move up and down) allow aircraft to turn. If you really want to learn more about how this works, you can read up on Bernoulli’s principle..And for the young aviators out there, check out our How Planes Fly video.

  • The dings
    Dings, or chimes as we call them, are a means of communication between the members of the flight crew. You will hear a chime when the fasten seatbelt sign is turned on and when the pilots make a call to our inflight crewmembers in the cabin. And the plane reaches an altitude of 10,000 feet you will hear two chimes, indicating that service may begin if conditions warrant.

Is there a concerning sight or sound you have encountered on board that you have wondered about? Post it in the comments and we will do our best to explain it!