Is it true that jets are pressurised to 8000ft? I'm curious because if that's the case why can I feel top of descent in my ears from 30+ thousand feet?
Wouldn't we have to go through 8000ft before my ears started to feel the increase?
Unfortunately my ears are very sensitive to pressure - I can feel the difference between the top of Bondi Road and Bondi Beach (for those who don't know that's maybe a few hundred feet).
Bane of my life, so I'm curious why I feel a pressure change so high up.

We start the cabin descending at around the same time as we start the descent.
The cabin usually descends at around 300-500fpm (feet per minute) while the aircraft could be doing any thing up to 3,000fpm.
Believe me, you don't your ears or any other cavity doing that rate.

redsnail has nailed it. :ok:

All I'll add is by the time the aircraft has descended to 8000', the cabin is around 2000' or less.

Ever heard of Google or Wikipedia?

Try this.

Cabin pressurization - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Cabin_pressurization)

Wageslave, this is the 'questions' area on an aviation forum, seems like a reasonable sort of place to ask that....

Unfortunately my ears are very sensitive to pressure - I can feel the difference between the top of Bondi Road and Bondi Beach (for those who don't know that's maybe a few hundred feet).
Bane of my life, so I'm curious why I feel a pressure change so high up.
Besides the cabin controller starting the pressurization change at Top of Descent, bringing the throttles to idle will often have a temporary effect while all the valves catch up with the change in airflow through the system.

Actual cabin pressure depends on the airplane and cruise altitude. It may be as high as 8,000' or as low as sea level (for a short, lower-altitude flight). The cabin controller tries to maintain a specific pressure differential (typically in the 8-10 PSI range) from the atmosphere at higher altitudes.

My ears are also sensitive to changes, but I often consider it an advantage. I occasionally catch an anomaly before others do...

Thanks for the replies...I could have googled but I think it's best to consult those who use the system....

Ideally the Cabin Altitude Rate of Change on descent should be no more than 300 feet per minute, anything greater can cause discomfort to some.

Sea level pressure is 14.7psi. Atmospheric pressure at 35,000ft is 3.2psi, at 43,000ft it is 2.3psi. Allowing the cabin interior pressure to drop to the level equivalent to 8000 ft (10.4psi) reduces the pressure differential at cruise by 4.3psi vs. what it would be if the cabin pressure remained at sea level. If the cabin altitude is kept at 6000ft (11.3psi) the reduction in pressure differential at cruise is 3.4psi.

Much of the fuselage structure of an airplane is life time limited by the number of times that it is pressurized and the maximum pressure differential that it sees. As a consequence, operators must carefully track the number of flight cycles an airplane makes as well as the total number of flight hours.

For aluminum fuselages metal fatigue becomes a design issue leading most aluminum commercial airplanes to be designed for 8000ft cabin altitude at cruise. An advantage of composite fuselages is that they aren't as limited by fatigue and thus can be designed to carry higher pressure differentials. The 787 for example, is designed for a maximum cabin altitude of 6000ft.

I too have sensitive ears and have often noticed cabin pressure changes during taxi out to the runway prior to takeoff. On a recent flight I had my barometric altimeter (a mountain climbing tool gift from my father years ago) with me. I noticed that the cabin altitude dropped about 300 feet (i.e., pressure increase) below the true altitude of the departure airport prior to takeoff.

For aluminum fuselages metal fatigue becomes a design issue leading most aluminum commercial airplanes to be designed for 8000ft cabin altitude at cruise.
Not quite. Most are designed for a specific pressure differential at cruise, e.g., 8.9 psi for the 744. That MIGHT equate to 8,000' at MAXIMUM cruise altitude, but it does NOT equate to 8,000' at typical cruise altitudes.

http://desmond.imageshack.us/Himg464/scaled.php?server=464&filename=a320pressurizationflightprofil.jpg&res=landing