Tuesday, February 11, 2014

Effect of the atmospheric change to human ears.

Recently, there was a complaint made by one of the passenger travelling on Airasia flight somewhere from China to KLIA. He was complaining about the pain on the ears during the descent. He even mentioned about the speed the pilot was flying appeared to be faster than normal because the arrival was early by 30 minutes.
Early arrival is only possible if the pilot can shorten the flight time, mainly by track shortening ( with the approval by Air Traffic Controller ) flying at higher speed during the descent until 5000 feet ( with the approval or instructed by the controller , normal speed below 10000 feet is 250 knots) and tailwind condition during the cruise phase. During the descend, the rate can reach as much as 2500 feet per minute but the cabin, which is pressurised, only descend at the rate of 300 to350 feet per minute. This is possible with the function of the Cabin Pressurisation Controller with limit the rate, suitable for human body especially the ears.

I took these pictures during the descend recently on my flight from Perth, cleared for high speed below 10000 feet. There you go, 310 knots with the rate of descend at 2200 feet per min as indicated by the green needle on the right side. 
However , the cabin rate of descend is only at 300 feet per minute as indicated by the green arrow CAB V/S at the lower picture. With this rate, a normal healthy passenger will not feel any pain in the ear unless he is having a heavy flu, blocked nose or sinus problem.