Why airplane windows have tiny holes

If you've ever sat in the window seat on a flight, you've probably noticed the tiny hole at the bottom of the window. We asked the FAA why it's there, and they assured us it's totally safe. Here's why there are tiny holes in airplane windows. Following is a transcript of the video.

Why airplane windows have tiny holes. Air pressure drops as you get higher. But airplanes are designed to maintain air pressure at a safe level inside the cabin. So the air pressure outside an airplane is much lower than it is inside. This difference in air pressure puts a lot of physical stress on the airplane window.

Airplane windows consist of three separate panes. The outer pane deals with this air pressure difference. Thanks to the tiny holes in the middle pane, known as the "bleed hole." Its primary purpose is to balance air pressure. There's a small gap between the middle and outer panes.

The "bleed hole" allows pressure to balance between the passenger cabin and the air gap. Meaning the outer pane takes on the pressure while the middle pane acts as a fail-safe. The inner pane is "non-structural" but it helps protect the middle and outer panes from damage caused by passengers. The "bleed hole" also releases moisture from the air gap. This prevents the window from fogging up or frosting over.

This video was first published on April 1, 2016.