While using aircraft window for journey, some people use to adapt middle pane of aircraft for seating there is specific reason behind their choice of seating, while we see passengers as they entered into the plane expecting to have window seat so that they can enjoy the outside view from top of all. You don’t need to think hard or it is not a rocket science, it’s a Simple equation, window seat in plane is like the best table in the café on a busy street.
Although you have got window seat and you obviously watching down instead of up, the oceans, entire cities and lovely landscape, but sometimes once in a while you feel something interferes your view, a thing come across to your notice some sudden headaches or may be some smudges or a tiny hole appears at lower portion of window? what? A hole in the window?
Well, it’s nothing huge just a hole in the window and its tiny small, but you cannot ignore it once you sight it. its very interesting how this hole was lodged into a passenger window. There are 3 forms of cabin window panes, one is outer, then middle and the innermost. The one inner most was also scratch pane use to protect the next layer of window.
When aircraft climbs up the pressurization system tends to change however inside the cabin the air pressure is much more stable, meanwhile air pressure outside tends to drop when aircraft climbs to heights. Generally speaking, pressure inside airplane is much greater than outside due to which whenever plane faces unusual circumstances, it started scrumbling. Well middle and outer pane contains the tiny hole which then used to stable air pressure between outside and inside.
As Marlowe Moncur, director of technology for GKN Aerospace, a leading passenger cabin window manufacturer,
The purpose of the small bleed hole in the [middle] pane is to allow pressure to equilibrate between the passenger cabin and the air gap between the panes, so that the cabin pressure during flight is applied to only the outer pane.
Well, middle and outer system of tiny hole control the pressure of sky, but in any case the outer pane fails to do so, middle pane ultimately there for safety zone, even if any air leaked from middle, aircraft pressurized system is potent yet smart enough to maintain environment as normal.
It’s one function of window hole, while Bret Jensen further told about related function
which is to release out the moisture from air and block the particles of to get frost detaining in window. Thanks to breather hole which has been design for passenger safety level and controls environment airflow.
Well how Frost formed and gathered in a specific pattern, Moncur explains it in a simple way
Frost is caused by condensation of water when cabin air contacts the cold window surface.
Moreover, those pattern have some interesting background, the Physics comes in question here,
The circular pattern must be a function of window surface temperature, humidity of the cabin air and flow rate through the bleed hole.”