Have you noticed this tiny hole on plane windows? Well, there’s an important reason for it.
Have you noticed this tiny hole on plane windows? Well, there’s an important reason for it.
Many travellers who have taken to the skies will have picked up on a tiny hole at the bottom of the aeroplane window. Now, it has been revealed that there is a “really important” reason for it.
The hole, which is the size of a pinprick, can be found at the lower centre of the window and, like every other aspect of aircraft machinery, is a well-engineered and functional part of the plane’s design. It is often referred to as the “bleed hole”.
The hole’s purpose is all related to pressure, reveals news.com.au.
Henny Lim, a cabin crew member who works onboard Philippines airline Cebu Pacific, says flyers often question what the “mysterious” holes in the windows are.
“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,” she said in a TikTok.
“This is called the ‘bleed hole’. [It] helps to balance the pressure between the cabin and the outside air.
“It also has another purpose which is to release moisture and stop frost/ condensation from blocking your view.”
When a plane reaches cruising altitude, there’s a big difference in pressure between the air outside of the aircraft and inside the cabin, which is pressurised to imitate the atmosphere at lower altitudes, AFAR reveals.
Most window panes on planes have an outer, middle and inner pane, which are made from acrylic.
“The outer pane bears all the stress of cabin pressurisation,” Robbie Gonzalez, a writer for Gizmodo wrote regarding the windows.
The inner pane holds the pressure within the cabin in the “extremely rare” case the outer pane is broken.
Sunset aerial view through aeroplane window over wings. Flying at sunset and looking out of the window and enjoying the panoramic view. Travel and transportation concepts
“The purpose of the breather hole, which is located near the bottom of the middle pane, becomes clear: it serves as a bleed valve, allowing pressure between the air in the passenger cabin and the air between the outer and middle panes to equilibrate,” Gonzalez shares.
“This tiny little hole ensures that cabin pressure during flight is applied only to the outer pane … thus preserving the middle pane for emergency situations.”
If the pane was blown out, which is a rare occurrence, the inside pane is still intact and strong enough to maintain the pressure in the cabin, which gives the pilots time to drop to lower altitudes and ensure the cabin pressure lowers.
“According to the [Boeing] 737 maintenance manual, the middle pane is designed to maintain 1.5 times the normal operating pressure at 70 degrees Fahrenheit,” Gonzales added.
This means that passengers should not touch the bleed hole or cover it during a flight as it needs to be able to do its job properly.
