Umm. There are some excellent posts after your post S&T where you asked me to further explain myself. Perhaps you have already had a satisfactory answer?
In my post, I was not specifically referring to the JAR 300fpm guide. It would keep just about everyone not only safe but also comfortable. A good thing to aim for in "normal" descents.
So if you are in a lo-co descent which takes only twenty minutes, you will go from a cabin altitude of about 8000' to sea level at a rate of about 400fpm. As I and Pax Vobiscum have explained perhaps not very well, this would be fine at altitude but a little uncomfortable for some when the aircraft gets down near sea level.
So where did my 500fpm figure come from? Experience in unpressurised aircraft. Sorry, but usually we
have to descend at that rate to fly standard airways and instrument approach profiles. If a passenger is showing discomfort, I'll do my best to shallow the descent or even level off for a while.
Where did my 2000fpm (corresponding with about 5500fpm at airline cruising level) come from? Plucked it out of thin air as what is just bearable (I didn't say comfortable) for a healthy person in my experience. If you have a cold, there will be serious pain and perhaps barotrauma - but this is a very rare and potentially very hazardous situation. As others have said better than I can, it's deemed "acceptable" as an emergency procedure where normal health & safety rules go out the window. With all the air, if you'll excuse the pun...
I did not mean to imply either that airliners do actually descend at this rate - it depends on the emergency - or that it would be in any way acceptable in "normal" ops.
Obviously explosive decompression up high more or less instantly sends cabin altitude to actual altitude?
Yes. But this is extremely rare, and is often associated with structural failure. The golfer's situation was unusual because a bizjet contains very little volume of air in comparison to an airliner, so a leak will result in less time for pressurised air to leak out.
So at say 38000, with 12 minutes of O2, if decompression was explosive, pilot must get down to around 14000 where most pax can breath unaided before pilot can level off? So that is indeed 2000fpm. Very painful to me I am sure, especially on a slight cold day.
No. Even if pax comfort was relevant in this emergency (which it isn't), 2000fpm at altitude is the pressure equivalent of about 650fpm at sea level, increasing to about 1500fpm equivalent as the aircraft approaches 14000'. So saying 2000fpm, while technically true, makes it sound worse than it actually is. I don't minimise the discomfort for most pax, and even perhaps injury-causing pain to a proportion of passengers.
Quite apart from the ear discomfort of a rapid descent, what about suffering the bends?
Not such a problem as you might think. The pressure change from aviation depressurisation is no more than the pressure change from surfacing quickly through 5m of water. I suppose there's a chance of the bends, but it's not likely.
My sincere apologies for the size of this huge post, and I hope it was slightly interesting without being too far off thread.
Cheers, O8