Why do airplanes get louder when approaching the airport?



I live about 20 miles from a busy airport and am underneath one of the approaching flight paths. Often when a commercial jet passes overhead, it suddenly gets much louder, sort of like a car shifting down. It definitely sounds like the turbines are revving up. Why would an airplane get much louder while descending?

In: Engineering

Part of it is because it’s descending, so getting physically closer. The main reason though is because aircraft land into the wind. That means as you’re looking at it coming towards you, the wind is blowing the engine noise away from you. As it passes overhead and continues away from you, the wind is now blowing the noise to you.


planes land with they’re noses pointed upward, flaps up and landing gear down. All this creates drag. When there’s too much drag, the plane slows down too much and the plane starts falling too fast. To not fall so fast, more power is needed by the engines for a soft touchdown or to fall down slowly and also make it to the runway.

There’s more to it as well like the surroundings of the plane, etc

I haven’t seen anyone mention how slowly the engines spool up and down. Until you’re on the ground and slowed significantly, you always need to have a plan to abort the landing. You’re going super low and slow by the time you near the ground. You’re going to run out of energy and stall if you try to abort the landing and go around without adding thrust. Eventually you get close enough to the ground that you can’t just add power from idle and expect the thrust to come before you’re out of time, so you rev the engines up a little. That way you’ll be making good thrust in a second or two rather than needing to wait several seconds.

Edit: [Source](https://www.google.com/amp/s/amp.usatoday.com/amp/1046488001)