Ears a poppin'
Thread Starter
Join Date: Nov 2008
Location: australia
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Ears a poppin'
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.
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.
PPRuNe Handmaiden
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.
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.
Ever heard of Google or Wikipedia?
Try this.
Cabin pressurization - Wikipedia, the free encyclopedia
Try this.
Cabin pressurization - Wikipedia, the free encyclopedia
Join Date: May 2000
Location: Seattle
Posts: 3,196
Likes: 0
Received 0 Likes
on
0 Posts
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.
Bane of my life, so I'm curious why I feel a pressure change so high up.
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...
Last edited by Intruder; 15th Jun 2012 at 19:17.
Join Date: Feb 2008
Location: Wingham NSW Australia
Age: 83
Posts: 1,343
Likes: 0
Received 0 Likes
on
0 Posts
Cabin Pressure Change
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.
Join Date: Feb 2009
Location: Seattle
Posts: 379
Likes: 0
Received 0 Likes
on
0 Posts
Cabin Pressure Observations
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.
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.
Join Date: May 2000
Location: Seattle
Posts: 3,196
Likes: 0
Received 0 Likes
on
0 Posts
For aluminum fuselages metal fatigue becomes a design issue leading most aluminum commercial airplanes to be designed for 8000ft cabin altitude at cruise.
