Why do your ears pop when you're on an airplane (and how can you stop it)?

Your ears pop because of the difference in pressure between the air inside your ear and the air outside. As you get higher up, the air is less dense, meaning there’s less air pressure pushing on your eardrum from the outside and more pressure on it from the inside. The ear regulates its internal pressure through structures called the eustachian tubes, and when these tubes open and allow outside air into the ear, we experience that as a pop.

With that in mind, you don’t want to stop your ears from popping; rather, you want to encourage it.

Tricks to avoid uncomfortable pressure on your eardrum include anything that encourages frequent swallowing, like Chewing Gum. Yawning also helps. Or, you could try something called the Valsalva maneuver, which entails holding your nose shut, closing your mouth, and gently blowing, as if you were blowing your nose.