To care for critically ill and injured patients in the air medical setting requires a basic knowledge of the forces affecting an aircraft and the forces that affect humans within that aircraft. Classic aerodynamic forces are lift, gravity, thrust, and drag. The forces affecting humans include vibration, barometric pressure, acceleration, spatial disorientation, and thermal stresses, among others. Provision of emergency care in the aerospace environment poses a number of challenges. Air medical crews must be mindful of the unique characteristics of the airplane or helicopter in which they are providing care. Pressure and temperature changes can significantly affect the patient and the crew. Noise, vibration, and other aircraft effects will alter the way in which care can be delivered. Special consideration must be given to protect the patient and the crew from the environment and the emergencies that can arise as the result of flight.