Originally Posted by
EyeWideShut
.... regarding cabin altitude rate of climb reaching 2,000-2,500 ft/min without noticeable discomfort, human physiology (say, of the eardrums) is not known to differentiate between ascent and descent – only between rates of change of atmospheric pressure. Therefore your comment about descent effectively supports the logical assumption that the discomfort (especially with 25 children on board) would indeed be very noticeable at a much earlier stage of the takeoff than FL120 when the Horn started beeping.
This question about the general symptoms in rapid cabin pressure ascent and descent has been mentioned before, hasn't it?
You would not expect a difference, but there is one. JAA maximum permitted rate of cabin pressure descent during normal operation is only -300 feet/min i.e. a whopping minimum nearly 27 mins for a normal descent if the cabin altitude reaches 8000 feet in the cruise.
The JAA maximum permitted rate of ascent is I believe +500 feet per min. I don't know the theory behind these JAA differences, although my old physics with biophysics degree head is actually quite capable of accepting that there probably IS a physiological difference between pumping out your inner ear through the Eustachians on the way up and pumping it up the same way on the way down. A bit like a football bladder in reverse perhaps?
My daughter is something of a mineshaft canary for monitoring what happens. She suffers from inflammed Eustachian Tubes more than the average person as she has childhood asthma and is allergic to housedust/seatdust etc. She NEVER has a problem going up although she notices it. She almost ALWAYS has a problem coming down which reduces her to tears if she is unprepared with earplugs and maybe Calpol if we know she starts the flight under par. This is especially the case when the JAA limit is 'somewhat tested' on the way down.
Edit: Got there before me BOAC!