A note about aircraft pressurization:
Modern turbine airliners can climb at impressive rates exceeding 4000 feet/min; however, the pressurization controllers maintain a comfortable cabin climb rate of between 350 and 500 feet per minute. The cabin ascent rate will never exceed the aircraft ascent rate unless the aircraft is pressurized on the ground (this is bad and doesn't happen often due to squat switches and outflow valves). At slow climb rates the cabin ascent rate can be very low and less than 100 feet per minute.
Depressurization: The descent rate of the cabin will never exceed the descent rate of the aircraft unless the aircraft reaches the cabin altitude due to a rapid descent with an outflow valve problem (rare and would be very obvious to the pilots). Cabin descent rates are typically in the 250 to 400 feet per minute range. The cabin altitude will reach ambiant ground pressure well before the aircraft touches down, and the max pressure differential upon weight on wheels is typically .1 or less.
Typical pressurization problems do not result in a rapid or sudden decompression of the cabin. Airplanes leak pressure by design. As long as the input produced by the packs exceeds the output (leakage), the plane will maintain a positive pressure differential. The normal leakage, supplemented by multiple outflow valves allows a differential to be maintained. A typical pressurization problem presents itself before the cabin pressure can rise significantly and is addressed with a descent to a safe altitude at an significant rate to exceed the climb in cabin altitude.
If there is a rupture of the hull causing rapid cabin altitude increase, you will be having one of those days that will most likely end very badly for all involved; therefore, whether or not you had residual inert gas in your system would be fairly irrelevant.
That all being said, things do go wrong, but the chances are very minor. You have to decide, like with things like depth, PO2, END, and such, what your tolerance of risk/reward is.
Modern turbine airliners can climb at impressive rates exceeding 4000 feet/min; however, the pressurization controllers maintain a comfortable cabin climb rate of between 350 and 500 feet per minute. The cabin ascent rate will never exceed the aircraft ascent rate unless the aircraft is pressurized on the ground (this is bad and doesn't happen often due to squat switches and outflow valves). At slow climb rates the cabin ascent rate can be very low and less than 100 feet per minute.
Depressurization: The descent rate of the cabin will never exceed the descent rate of the aircraft unless the aircraft reaches the cabin altitude due to a rapid descent with an outflow valve problem (rare and would be very obvious to the pilots). Cabin descent rates are typically in the 250 to 400 feet per minute range. The cabin altitude will reach ambiant ground pressure well before the aircraft touches down, and the max pressure differential upon weight on wheels is typically .1 or less.
Typical pressurization problems do not result in a rapid or sudden decompression of the cabin. Airplanes leak pressure by design. As long as the input produced by the packs exceeds the output (leakage), the plane will maintain a positive pressure differential. The normal leakage, supplemented by multiple outflow valves allows a differential to be maintained. A typical pressurization problem presents itself before the cabin pressure can rise significantly and is addressed with a descent to a safe altitude at an significant rate to exceed the climb in cabin altitude.
If there is a rupture of the hull causing rapid cabin altitude increase, you will be having one of those days that will most likely end very badly for all involved; therefore, whether or not you had residual inert gas in your system would be fairly irrelevant.
That all being said, things do go wrong, but the chances are very minor. You have to decide, like with things like depth, PO2, END, and such, what your tolerance of risk/reward is.
