cabin pressure - Can the RAM AIR valve cause depressurization on the CRJ-900?

On the CRJ-900 AIR-CONDITIONING panel there is a RAM AIR switch light which opens a valve and allows air from the ram air scoop to enter the mixing manifold for distribution to both the flight deck and passenger cabin.What would happen if the valve were opened at high altitude? Would this cause depressurization?When I received CL-65 type rating I was taught that there was a protection that would prevent the valve from opening. I have also heard this was a mistake in the manuals and that it would open and cause depressurization. I have also been...Read more

crew - Is the air in aircraft cabin toxic?

I just listened to the recent BBC podcast episode Aerotoxicity: the hidden dangers of flying and there were interesting claims there:Cabin air in modern passenger aircrafts comes directly from engines (it's called bleed air).This air is unfiltered and during so called fume events it may contain toxins from engine oil and other fluids. These toxins are called Tricresyl phosphate and persons exposed to them for a long time may suffer diseases of nervous systems, from psychological problems like depressions to neurological symptoms, like unexplain...Read more

cabin pressure - Do pilots breathe the same air as passengers?

Do pilots breathe the same quality of air as passengers ?(i.e. identical parameters: same O2, CO2 and O3 levels, same temperature, same humidity, etc.)Do pilots breath the same air as passengers (shared air) ?(i.e. the air a passenger exhales will be inhaled by the pilot [or vice verca], which also means that smoke in the cabin will inevitably end up in the cockpit)...Read more

accident investigation - How does the Learjet cabin pressurisation system work?

In one of the MAYDAY Air Crash Investigation episodes (about the Payne Stewart crash), the flight's emergency manual had the following information under the cabin pressurisation section: NOTE: At 10,000 (± 500) Feet Cabin Altitude, control pressure to the outflow valve is trapped. This deactivates the Automatic Mode and stops cabin altitude from rising higher if the failure is in the automatic control system.What does it actually mean? As the NTSB investigators mentioned, it sure does sound confusing....Read more

How does the outflow valve work on a cabin pressurization system?

When you fill up a cabin with warm air the pressure of the cabin will rise. An outflow valve controls the desired pressure. But with pressure rising doesn't the temperature rise because you're compressing air into a space? Is this why the outflow valve is there, to regulate the pressure and temperature? Does the outflow value open and close depending on the pressure during phases like climb, cruise, and descent. Or does the outflow valve shut completely once the cabin altitude reaches 8,000ft? But then wouldn't the air get too hot because it k...Read more

Why aren't aircraft cabins pressurized to sea level pressure?

From an article on WHO's website: Although aircraft cabins are pressurized, cabin air pressure at cruising altitude is lower than air pressure at sea level. At typical cruising altitudes in the range 11 000–12 200 m (36 000–40 000 feet), air pressure in the cabin is equivalent to the outside air pressure at 1800–2400 m (6000–8000 feet) above sea level. Why aren't cabins completely pressurized, but instead to 6000-8000', seeing that many passengers wouldn't have to endure sometimes painful popping in the ears?...Read more

cabin pressure - Can air travel cause packaging air pads to burst or deflate?

This question is a new cross-post from the physics stack exchange: received a parcel from Germany to Chile. The contents were severely bruised due to a lack of packaging material. On second inspection I found a bunch of deflated air pads.It was a personal shipment, the air pads were used and potentially not in pristine condition, but there were several brands of them, a manufacturing defect can be ruled out. It seem...Read more