Normally you feel pressure in your ear, if the air pressure changes, e.g. if you're ascending or descending very fast. But why do I feel this pressure also in airplanes where the pressure in the passenger room should be constant?
The cabin pressure is not constant - it's allowed to drop as the plane ascends, within safe levels (typically down to the pressure one would find at between 1500 and 2000 meters of altitude).
The reason for this is that a pressure difference between inside and outside puts stress on the fuselage. Reducing the maximum difference allows the fuselage to be lighter, which makes the plane consume less fuel.
The pressure is not constant in an airplane. For minimizing delta between inside and outside, air pressure in an airplane is set to the one found at an altitude of about 3000m or 10000ft.
Therefore, if your airport is at sea level, like New York for instance, a take off is equivalent to climbing mountains in Montana or in Pyrénées.
Well, for starters, the pressure DOES actually change in the cabin as you climb / descend.
The discomfort some people experience during this - when your ears can actually be in some pain - is known as Barotrauma - and as the name suggests, is trauma from barometric pressure. It comes when the gases trapped in your body expand or contract as the pressure ratio changes. The most common problems occur with air trapped in the middle ear or sinuses by a blocked Eustachian tube or sinuses. It can also cause pain in the stomach or even the teeth!
If you're trying to relieve the pain, we have some tips on this very site!
There are so many variables to take into account:
- Ambient Temperature of the airplane (lower temp = lower pressure)
- Type of airplane and its volume capacity (large boeing 747 = lower cabin pressure)
- Humidity of air ( higher humidity = higher pressure)
- Flight path (over sea lower altitude compared to flying over land at higher altitude with higher pressure)
- Your acclimitized altitude ( if you live at sea level you will notice a greater difference in pressure than if you live 500metres above sea level)
- Other smaller things; time of day, meteorological weather , passenger count, latitude .......
Firstly if the plane is pressurised then you are right, the pressure in your ears should be constant. However the pilot is able to adjust the cabin pressure, it is this that that is causing the barotrauma. Pilots do this to cause people to feel sleepy (by lowering the cabin pressure).
If a pressurised plane leaks or gains pressure then it also leaks air, this is a very dangerous situation.
Secondly if your plane is not pressurised then the comments about altitude do apply, but your plane will not fly at altitudes that make it hazardous.