During vehicle submergence, at least 1 window per row of seats shall be able to be opened to allow occupant escape, and shall remain openable for at least 2 minutes from water entry. The vehicle shall be lowered into a water-filled container within a 10-degree horizontal angle in X longitudinal and lateral directions. T0 is counted from when lowering straps slacken and the vehicle floats. After 2 minutes of floating, the window must be opened to its lowest position, or automatically lowered if equipped with automatic window lowering system. Alternative sub-system tests demonstrating window opening functionality under water, in agreement with the approval authority and its designated technical service, are acceptable. The test is fulfilled if the window is open to its lowest position after the test.

A design is intuitive when users understand and use it correctly and efficiently without needing instructions or prior training. Key signs include matching user expectations, requiring little explanation, giving clear feedback, minimizing thinking, maintaining consistency, and building on familiar patterns. For emergency door opening, intuitive design requires interior release control to unlock doors and unlatch without separate controls. Alternative actions for power loss must be fully intuitive, integrated or in close vicinity, within reach, and properly marked. Exterior door handles need a proper force application area for at least four fingers of an adult hand.

Proposal to establish a submergence test procedure requiring that at least one window per row of seats be capable of being fully opened after a vehicle enters water for occupant escape, with the window operable up to 2 minutes after submergence as designed by the manufacturer, defining container dimensions to accommodate the vehicle without wall or floor contact during the 2-minute period except when fully submerged, permitting open-water test sites provided they comply with test conditions while prohibiting freshwater lakes, reservoirs, and saltwater bodies, requiring the master control switch position allow window operation, specifying unladen kerb mass with measuring apparatus not changing axle reference load by more than 5 per cent, lowering the vehicle into water-filled container at horizontal angle 0–10 degrees with time zero defined as when lowering straps become slack and vehicle floats freely, requiring the vehicle remain in water for 2 minutes from time zero without floor contact until fully submerged, requiring window operation by remote system after 2 minutes with vehicle immersed, and permitting alternative subsystem tests demonstrating window opening functionality under submerged conditions.