First, comatose patients require close observation and care, which may be more convenient in home or hospital conditions. On an airplane, observation and care of the patient may be limited by space and conditions.
Second, flying may have an impact on the patient's condition. Changes in air pressure and changes in oxygen concentration on airplanes may have an effect on the patient's body, leading to deterioration of the condition. In addition, stress and fatigue on the airplane may adversely affect the patient's recovery.
Finally, if a patient needs to be transported, it is best to do so under stable conditions. On an airplane, conditions may make it difficult to provide the necessary medical equipment and medications, and thus there may be risks to the patient's safety.
Overall, patients who are unconscious but not in a life-threatening condition are best treated and observed in a ground hospital. If air travel is necessary, it is recommended that it be done in the company of medical personnel and with the necessary equipment. It is also necessary to get a doctor's exact permission to fly.