Lack of oxygen is one of the greatest single danger that man can experience, especially airmen/pilots. A lot of accidents happened because of it. In this paper we will discuss what hypoxia is, why it is so dangerous to the pilots, and how pilots should deal with it. Hypoxia, by definition, is the lack of sufficient oxygen in the blood, tissues, and/or cells to maintain normal physiological function (Boshers, n.d.). Hypoxia could be cause by many different reasons and at any altitude, that’s why there are different types of hypoxia. One of them is called Hypoxic Hypoxia, and it is the most common type of hypoxia. Hypoxic Hypoxia happens when there is simply not enough oxygen to breathe in. For example, at high altitudes when aircraft gets depressurized pilots will most likely experience it, due to the lack of oxygen quantity at high altitudes. Another type is called Hypemic Hypoxia. It happens when blood’s ability to carry oxygen is reduced. Sulfa drugs, nitrites, and hemorrhage are some of the reasons blood is not able to carry oxygen. However, the most common reason is usually carbon monoxide poisoning. It usually happens because of aircraft heater malfunctions or engine manifold leaks. The less common type is Histoxic Hypoxia, cell expecting and needing the oxygen is impaired and cannot use the oxygen to support metabolism (Boshers, n.d.). Basically, cells are unable to accept and use oxygen because of alcohol and other drugs.Pilots who are exposed to hypoxia may experience symptoms such as: euphoria, excessive yawning, impairment of mental task, and others. Some pilots might be better at tolerating hypoxia than others, however, if ignored everyone will suffer. The first symptoms of oxygen insufficiency are somewhat pleasant, resembling slight intoxication from alcohol. Because oxygen starvation affects the brain first, your mental capability is reduced. Your judgment is not working as it is supposed to work. Your hands and feet become uncoordinated without your knowledge; you may feel sleepy, relaxed, and unconcerned; pilots may have a false sense of security; and pilots don’t usually think that the first thing they need is oxygen. If you stay long enough without the oxygen there is high chance of blacking out and eventually dying.So how does one prevent or deal with Hypoxia? Because hypoxia is subtle and because the signs and symptoms are vary between individuals, the best and most effective thing you could do to reduce your risk of becoming hypoxic is to attend a formal course in aviation physiology (Boshers, n.d.). High altitude chamber simulation would give you the opportunity to experience hypoxia for yourself, and see what symptoms you experience first, so that you know when hypoxia is happening and you would also be able to see symptoms of other people (Boshers, n.d.). If you find yourself experiencing hypoxia you need to immediately put on the oxygen mask. Also, worry about yourself first, do not try helping someone else until you have adequate oxygen supply or you are risking blacking out. Overall it may be said that hypoxia is extremely dangerous, especially to pilots. There are many different types of Hypoxia and it could happen either on the ground or at 40,000 feet. Going to high altitude chamber and experiencing it will help you to identify the symptoms, and will reduce your chance of dying. If you are experiencing hypoxia worry about yourself first and then others.