Ears and Congestion
The air thins with increasing altitude. As a result, a person experiences pressure changes as the airplane climbs and descends. These pressure changes have many effects on the body. One of the easiest ways to sense a change in pressure is through the ears, as a popping or full feeling. The is caused by a pressure difference between the air inside the ear and the air in the environment, outside the ear. The air inside the ear is sealed from the outside air by the ear drum. A small tube, called the eustachian tube, leads from the inside of the ear to the throat, and opens to equalize any differences in air pressure.
As the airplane climbs, pressure outside the ear decreases. The ear still contains the higher pressure air from lower altitude within. That higher pressure air normally escapes through the eustachian tube, producing very slight or no feel. If it is unable to escape, however, a pressure difference is created. The higher pressure air inside the ear then forces the ear drum to bulge out, toward the lower pressure outside. This bulging can be felt. Since it affects the operation of the eardrum, hearing is also affected.
It is not as very common for someone to have ear and sinus problems during the climb. The air tends to find its way out, even when a person is congested. It is more common for ear and sinus problems to present themselves during the descent.
As the airplane descends, pressure outside the ear increases. Air normally enters the ear and equalizes any pressure differential during the descent. If a person is congested or naturally more susceptible to such problems, the path to the inner ear may be blocked. In this case, the ear contains low pressure air from aloft. The increasing outside air pressure squeezes the ear drums, causing them to bow inward. This inward bowing can be felt and affects hearing. As the airplane continues to descend, the pressure differential continues to increase. The squeezing of the ear drums can become painful. In a worst case scenario, it is possible to even damage or rupture the ear drums.
Usually, swallowing of chewing gum will help to open the eustachian tube sufficiently to relief most or all of this pressure differential. If this is ineffective, it may be necessary to climb to an altitude which relieves the pain and allow the ears more time to adjust, before beginning a gentle descent.
Because of the tendency for ear and sinus problems to wait until the descent to show up, it is advisable not to fly when congested at all. It is important for the pilot to ensure passengers are not congested as well. They may not seem sick and report feeling fine, but have problems during the descent.
Sinus and Congestion
Air may also become trapped inside the sinus cavities, located behind the nose. Under normal circumstances, slight pressure differences present themselves as small sensations between the eyes or behind the lower portion of the forehead. If a person is congested, however, these slight sensations quickly become painful. In severe situations, it is possible to damage the tissues surrounding the sinus cavities, causing them to bleed.