I had a 8-10,000 fpm cabin climb in the Lear 35 one evening while at FL30-something. The Altitude claxon isn't all that different from the gear or overspeed (been 2 years since I've flown it, so I've forgotten a little).

The Capt started messing with the cabin pressurization switches while I yelled "Get your mask on!!" The stock masks in the Lear are crap...VERY uncomfortable, very flimsy, and difficult to don correctly/quickly. I should point out he was a civilian background, and had never been in an altitude chamber.

I got my mask on and put the controller in Manual and managed to catch it before it went above 25,000 cabin altitude.

The cabin outflow valve in the Lear family is a piece of plastic, and can fail quickly to leave a 3-inch hole in the cabin and outside air. You could lose all pressurization in as little as 3 seconds, by my estimate, at FL410.

And my point about the Capt above was many civilians have no idea how quickly you can become incapacitated in the rarified air above FL250, particularly in the 30s and higher, because they've never been exposed to it in the altitude chamber. Time of useful conciousness at FL410 is about 10 seconds without the mask.

I've said this before on a different post: wear your mask as required by the regs, and if you can get a chance to use the FAA's free program to ride in a military chamber, do it. Call the FAA at Oklahoma City and ask about the program, and they will set you up with the closest military installation.