make sure to feed the fuel from the higher wing…
10,000 feet to 9,000 -3.7% change
3000 feet to 2000 -3.6% change
(using tables on www.engineeringtoolbox.com/air-altitude-pressure-d_462.html))))
But then the absolute pressure change remains bigger so e.g. if your eustachian tube is completely blocked, the same maneuver lower down is going to create a bigger pressure differential and hurt a whole lot more.
KWIF, you are wrong on several counts…..1. The absolute pressure change from 10-9k’ (about 700-733 hPa) is about the same as the absolute pressure change from 3-2k’ (about 900-933 hPa)….as you can see from the link you posted in the range we are talking about pressure decreases more or less linearly wih altitude (around 30’ per hPa or 33 hPa per 1000’)….2. as a percentage 33/700 = 4.7% and 33/900 = 3.7%….3. Boyle’s law (which says in effect, that the percentage change in absolute pressure is inversely proportional to the percentage change in volume) explains why the 1000’ descent at the higher initial altitude creates a greater change in volume of air which needs to flow in to your middle ear via your Eustachian tubes to equalize pressure. If your E tubes are blocked and you can’t equalize the your ear drum and middle ear tissue will attempt to fill the void thus causing pain….__slightly more __pain at the higher altitude…
Where are you getting your numbers from? And I would hardly call that graph linear.
The link I posted has a table as well as a chart -
10,000 feet – 523 (534)
9,000 feet – 543 (554)
3,000 feet – 681 (685)
2,000 feet – 707 (709)
10,000 → 9000 = pressure drop of 20 hPa. 20/523*100 = 3.8%
3000 → 2000 = pressure drop of 26 hPa. 26/681*100 = 3.8%
Slight numerical differences depending on units/source caused by rounding errors.
Alternate values from http://www.altitude.org/air_pressure.php
The pain caused by an unequalised ear is due to stretching of the tissues surrounding the ear – particularly the tympanic membrane – which will be proportional to pressure differential rather than the volume required to equalise – as per Laplace.
Ok, I started with the assumption that in the range of 0 to 10000’ (0 to 3000m)the pressure varied linearly…you are correct this is not strictly the case…close, but not exact…
Using your reference the percentage differences are 3.9% (not 4.6%) and 3.7% (not 3.6%)….so agreed more or less the same percentage changes from 10-9k’ as 3-2k’….so there should be no discernible difference in discomfort when descending by 1000’ from 10000’ vs 3000’…..which was actually my original point!
So, notwithstanding that you meant mmHg instead of hPa, you are completely right after all! 
Nvertheless, subjectively, I agree with Peter. I notice more ear pressure in rapid descent below 8000’ than from FL140 to FL100. Because of that I try to slow ROD below say FL90.
.so agreed more or less the same percentage changes from 10-9k’ as 3-2k’….so there should be no discernible difference in discomfort when descending by 1000’ from 10000’ vs 3000’…..
Touche regarding mmHg.
But when it comes to the effect of pressure changes, the absolute pressure differences will be different – 20 mmHg going from 10k to 9k and 26 going from 3 to 2.
Think of the middle ear cavity – it’s a bony space 0.5-1mls with another 4-20 mls of air within the mastoid bone. There’s a relatively compliant membrane (the eardrum) but this is small and will only allow for a small amount of volume change in the middle ear. If you were to block the Eustachian tube completely the amount of pain (tension in the membrane) would be entirely dependent on the pressure differential. It wouldn’t matter how small or great the volume of air needed to equalise the pressure is because that process wouldn’t be happening to a great extent.
I don’t see why the percentages matter? Surely, the absolute pressure differential it the important thing!
As much as I hate to re-enter this fray….if you take a scuba diving example, the absolute pressure change from say 95m to 100m depth (10.5 bara to 11.0 bara) is the same as the absolute pressure change from 5m to 10m (1.5 bara to 2.0 bara)…..however as any diver knows in terms of equalization of the ears the latter is far more significant….because if you are unable to clear your ears the required volume change of any air in the middle ear (in order to equalize pressure) is 5% vs 25%…..in the former case some swelling of the tissue and deflection of the ear-drum (tympanic membrane) will likely be enough to equalize the pressure….however in the latter case this will likely lead to a ruptured eardrum…but also as discussed above, this is not particularly relevant to aviation in terms of the difference in effect at different altitudes
Isn’t the big difference between water and air is that water is not compressible, so the pressure change between 100m and 95m is the same as between 10m and 5m.
I only re-entered for the edification of Airborne Again!….ie it is not just the pressure difference but the ratio of absolute pressure difference (which I expressed as a percentage)….and yes, as very well established by KWIF, for the atmosphere the fact that air is compressible means the effect of changing altitude is relatively unaffected by the initial altitude
