I recently had the privilege to go for a 'flight' in the altitude chamber at KIWA as a part of my area of study (aviation physiology). This chamber flight was also my first experience using an aviators style full face oxygen mask (I don't know its technical term, Im afraid). I wasn't expecting there to be such a noticeable increase in effort required for respiration, and initially, I was concerned that I had a problem with my equipment (in fact, at first, my unit wasn't allowing me to exhale). I came to grips with the reality of it and reasoned that it must be due to having to breath through a long tube and what ever other valve/mechanical systems gets in the way of my oxygen.

This got me to thinking though, presumably, fighter/mil pilots who are on O2 for the entirety of a flight: Q. doesn't the increased resistance to breathing normally become a nuisance when your heart rate is accelerated during stressful flights (i.e. combat/aerobatics/emergency etc)?

But at any rate, the experience was highly valuable, as I was able to experience first hand in a safe environment what my initial symptoms are to hypoxia. It was pretty amazing how quickly my motor and mental skills diminished at an altititude of 25,000'. Trying to mulitply 25 x 3 has never been so hard in my life!

Interestingly, I was the only guy on my particular chamber flight of about 12 guys that experienced a perceivable degradation of acuity in my vision. Otherwise, I had the usual tingling sensation in my fingers and a general sense of euphoria.

I imagine most if not all of you mil guys have had this opportunity, so you would all agree in just how valuable of an educational experience it is....and if anyone else gets the chance to go for a flight in the alt. chamber, do it!

AZ:

The Oxygen comes in the hose, but goes out (assuming a USAF-style mask) from a black valve on the right side of the mask.

The exhalation valve often sticks, and it is a pain. I found a simple solution: hot water.

During a typical rockin' and rollin' fighter type of sortie, you will sweat, work hard under "g," and transmit on the radio to your wingmen while straining against "g" (ie, you will be speaking loudly or almost shouting). As such, sweat and or spit/snot tends to go out the valve.

It dries there, but it isn't really visually noticable. Next time you fly, moisture in your breath makes the dried gunk sticky again.

Life-Support technicians wipe down the mask between flights with alchohol, but don't wipe out the valve (not really accessible).

So, I flush my mask with hot water about every two or three weeks. My valve never sticks, and I still get a good seal for the O-2 check. Not the book answer, but I've shown this to a lot of guys who said it finally fixed it for them.

There is a new device out there that has made the altitude chamber nearly obselete for hypoxia training. It is called the ROBD (Reduced Oxygen Breathing Device). You can sit comfortably in front of your computer flying MicroSoft FLight Sim if you want to and then the techs turn some valves on and you can be hypoxic in only a few seconds - simulating that you are at FL400 if they desire. It is great training and has none of the bad side symptoms of the chamber ride.
As for the breathing - the O2 (100% in some cases) is being positively fed to you so it basically forces it down your throat!
The mask can be uncomfortable to wear for long durations and it can get in the way sometimes during tactical maneuvering, but it is what it is!

USMCFLYR

Classic, you mean the guy that had the super stuffed burrito for dinner the night before right! Of course, then there is all that other stuff...

AZ,
You quickly get used to breathing through the mask / hose. By the time you get to a fighter it's a non-issue. Yes, they do stick, mic's fail, stuff breaks, all part and parcel of gear that gets a regular work out.
Fighters now have a setting that allows for air to be forced into your mask while pulling G's, called Positive Pressure Breathing. Fortunately it's cockpit controllable so those of us who have survived all these years with out it can turn it off. It does have a nice function that it inflates a bladder in the back of your helmet that forces the mask against your face (preventing spillage of air).
Biff

Thanks for the clarification, men.

And yes..bad side symptoms of the chamber ride.....I think we were all doing the chamber dance. At least I was...

Dude, I wouldn't recommend doing that - for more reasons than just doing potential damage. Make the life support techs do their job right, they have ways they can clean the valve better then you can with hot water (long swabs, etc). Once a week tell them your valve is sticking and they will do the thorough cleaning - it's their job.

Was your Regulator in the "Emergency" position? Then you would have been exhaling against positive pressure.

Required training. One guy washed out of my UPT class after discovering an inner ear problem on the Chamber Ride.

AZFlyer,

I remember thinking the exact same thing after my first chamber "ride." This, in no way, mirrors the actual act of breathing through your mask during flight. The dudes in chamber had it set on emergency, like blastoff said. Breathing through the mask during flight is no big deal.

That was likely the issue.


This is something I am slightly (at the moment) concerned about.

2 summers ago, I ruptured (not severely) my right ear drum. My hearing in both ears was only temporarily impaired, and a recent hearing test has confirmed both of my hears measure in the 'perfect' range. However, I experienced some discomfort in my right ear for the next couple of days after the chamber ride. When I would blow my nose, for example, I would experience a brief sharp pain and I could audibly hear what sounded like air escaping from my ear. A few days go by, and Im fine again. I didn't have any issue at all during the ride itself, though, which is odd.

I haven't been in the chamber since, but since I will finish college fairly soon and am planning on making a go at flying ANG, I would hope to have this issue put behind me.