To understand in-flight ear pain you must first understand a little ear anatomy. Normally the Eustachian tube, which connects the middle ear to the back of the nose, helps equalize pressure between the middle ear and the outer ear. Eustachian tube size and function variesfrom person to person, and children tend to have narrower tubes than adults. When the eustachian tube is blocked, during a common cold, for example, or from allergies, pressures cannot equalize and a painful vacuum develops inside the middle ear. Often this will clear with time but sometimes fluid builds up, blood vessels burst, infection occurs, or the ear drum ruptures.
Hearing is usually muffled and in severe cases can be affected permanently.
Vertigo, a sensation of the world spinning, can also occur. Take a breath of air. Using your cheek and throat muscles, force the air into the back of your nose as if you're trying to blow your nose. When you hear a loud pop, you have succeeded. You'll probably have to repeat the procedure several times during descent.