Occupant physical environment.

§ 23.2320 Occupant physical environment. (a) The applicant must design the airplane to— (1) Allow clear communication between the flightcrew and passengers; (2) Protect the pilot and flight controls from propellers; and (3) Protect the occupants from serious injury due to damage to windshields, windows, and canopies. (b) For level 4 airplanes, each windshield and its supporting structure directly in front of the pilot must withstand, without penetration, the impact equivalent to a two-pound bird when the velocity of the airplane is equal to the airplane's maximum approach flap speed. (c) The airplane must provide each occupant with air at a breathable pressure, free of hazardous concentrations of gases, vapors, and smoke during normal operations and likely failures. (d) If a pressurization system is installed in the airplane, it must be designed to protect against— (1) Decompression to an unsafe level; and (2) Excessive differential pressure. (e) If an oxygen system is installed in the airplane, it must— (1) Effectively provide oxygen to each user to prevent the effects of hypoxia; and (2) Be free from hazards in itself, in its method of operation, and its effect upon other components. Fire and High Energy Protection