My friends laugh at me when I ask for a window seat. You’re an airline pilot, they say. You have the window seat all the time.
True enough. But the cockpit, well, that’s work. As a passenger I’m actually free to enjoy the experience—to listen to music or a long-postponed podcast while gazing out at the world below, to remember that it’s still a wonder to look down, not up, at clouds. The window seat is like the best table in a café on a busy street, except that instead of people-watching, entire cities, oceans, and mountain ranges parade past
When you travel on an airplane, you presume it to keep you safe and sound until you land to your destination. It’s not much to expect, really. But, what if I tell you that there are holes punched at the bottom of the window. Have you not noticed it before? Oh, damn! I can only imagine the panic you must feel at this very moment. Worry not! The hole is not planned out to get you sucked out in the open air, 30, 000 feet above the ground. But, if it’s not a well-planned conspiracy of murdering you, then why?
Here is the answer for Why Airplane Windows Have Tiny Holes At The Bottom?
Why Airplane Windows Have Tiny Holes At The Bottom?
Still, every once in a while something interferes with that view. Maybe it’s the forehead smudges left by your seat’s previous occupant. Or the little hole that appears in the lower portion of a typical airliner window.
Hole in the window? The little one, near the bottom, that you perhaps only notice when a hollowed-out snowflake of frost forms near it. This tiny hole is called a breather hole or a bleed hole, and it serves an important safety function.
If you look closely at a typical passenger cabin window, you’ll see three panes, typically made of acrylic materials. The purpose of the innermost pane—sometimes called the scratch pane, but I like to call it the smudge pane—is merely to protect the next one.
The middle pane (with the breather hole in it) and the outer pane are more important. Generally speaking, as an aircraft climbs, the air pressure drops in both the cabin and the outside air—but it drops much more outside, as the aircraft’s pressurization system keeps the cabin pressure at a comfortable and safe level. This means that the pressure inside the aircraft during flight is typically much greater than the pressure outside.
There’s still the matter of that small but lovely pattern of frost that can form near the breather hole on a long flight. At cruising altitude the temperature of the outside air can be minus 70 degrees Fahrenheit. The frost, according to Moncur, “is caused by condensation of water when cabin air contacts the cold window surface.” But what causes that telltale frost pattern? The physics behind it are an interesting question, he says. “The circular pattern must be a function of window surface temperature, humidity of the cabin air and flow rate through the bleed hole.”