Unknown facts regarding airplanes

If you have traveled in an airplane, then you must notice some unusual things in the plane and I bet most of you didn’t know why it is so…

Welcome to Engineering Master. In this article, we will explain some facts about airplane which you must have noticed while travelling but didn’t ever think WHY it is so?

The first fact is the round window. I have already written an article about it so please read it here (click here).


Many of us pay extra amount to get window seat on airplane to see outside view. But do you ever observe the window.

If you have observed, then you will find a tiny hole in it. These are present in all windows. But the main question is Why this hole is there in window? There are 3 layers/panes in the window.  The outer pane which is hard and pressure tight. The innermost pane is less hard and it protect other layers from scratch and damage. The middle pane has the hole, which is commonly known as breather hole. It is used to regulate the amount of pressure that passes between the window’s inner and outer panes. Since pressure changes in the cabin during the flight, it is necessary to equalize the pressure between the window panes and that’s why the window has hole.





At the time of takeoff and landing, the flight attendant ask you to open the window shades. Why do they ask us to open this? Whether they want us to watch takeoff or landing view? The answer is NO.  You must know that the most critical part of any flight is when it is near the ground. Those windows are not just for sightseeing. But, if something wrong happens with the power of the flight, then the only light (besides the illuminated arrows) will come from the window. And if someone have to open the emergency exit, then they need to check outside for fire, water or anything hazardous.

Whenever you board an airplane, you must hear unpleasantness sound. What is the source of the sound? Is the sound is from flight engine? The answer is NO. The sound comes from the Auxiliary Power Unit, commonly known as APU, situated under the tail of the airplane. APU provides temporarily electricity to the plane when it is in ground. APU is usually a small turbine that power generator for electricity and compressor for air pressure.  The APU powers everything (lights, fans, etc) up to the starting of the main engine. This system uses less fuel since it is designed for cabin operations only.



34 thoughts on “Unknown facts regarding airplanes”

  1. Recently flew for the first time in life and actually enjoyed it. First thing I noticed were those window holes. Figured it had something to do with air pressure Looks I was right.

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