An airplane cockpit is a mildly bad example, because even at airliner cruising altitude breathing the air is better than holding your breath; it may take a minute or two to lose consciousness, and you'll get to enjoy the dizziness, disorientation, brain fog and headache for many seconds. There's also the lack of overall pressure; breathing at high altitude is a strange experience, you can feel the lower density. Especially since most people who arrive at 35,000 feet cabin altitude get there in a pressurized aircraft which accidentally loses pressure, which isn't a comfortable experience at all.

On the other hand, imagine this: you're a sailor on a big steel ship. There are void compartments in the hull that are sealed airtight. All the oxygen in the air in there is used up by the rusting steel walls, so now you've got a room that doesn't have any reason to lack oxygen, but it does. You're sent in there to do some maintenance or repair, you open up the hatch, climb inside, everything is fine, you get to the part of the compartment where you're supposed to work, it's dark so you don't notice your vision narrowing, you bend over to get a wrench out of your toolbox, you suddenly feel lightheaded, pass out, fall over and just fucking die. And so does the guy who comes in to try to help you. The air feels the same to breathe because it went from "almost all nitrogen" to "all nitrogen." The CO2 can freely leave your body and doesn't get re-breathed, so it doesn't hurt. In this "absolutely no oxygen in the air at all" environment, you actually exhale oxygen out of your bloodstream, so breathing will kill you faster than holding your breath.

Alabama basically put the guy's head in a bag with extra steps; because he could breathe his own exhaled O2 and CO2, It killed him slowly and it hurt the whole time. "Botched" is the word for it.