I was flying with another pilot in a Lear 35a. Nice little bizjet.
Anyway, I have two young boys and their grandpa in the back. Picked 'em up at Teterboro NJ, and we flew them down to Tampa.
About fifteen minutes out, we get cleared down to 11,000. Low enough to think about the landing we will make, and still high enough that we can still go very fast, because below 10,000 we (aircraft) have a 250 knot speed limit.
So, one thing about the Lear is that cabin pressure enters at the rear of the cabin, and the pressure is controlled by outflow valves in front of our instrument panel, so all of the air that is in the back of the plane leaves by going by US first, in the front of the plane.
Well, at one point, Grandpa lets loose with about 50 years of methane and various other aspects of decaying alimentary particles.
I was raised on a farm, and even I started to gag. Almost by instinct, we BOTH reached for our O2 masks, and had them on in a moment. I cranked my regulator FULL OPEN.
Well, it WAS an emergency.....