Flight Training - July 2012 - 48

CAREER PILOT»

TECH TALK

The system that keeps you comfortable
» By Jared Dirkmaat

UNDER PRESSURE
jet engine, compressed air is drawn into the cabin and the pressure is maintained by controlling the outflow valve. The outflow valve usually is installed on the aft pressure bulkhead of the fuselage. It controls the amount of pressurized air allowed to escape the pressure vessel, thus controlling the cabin altitude. In most modern aircraft, the outflow valve is automatically modulated to maintain a desired cabin altitude. Previous designs required constant monitoring and adjustment of the outflow valve to prevent the cabin altitude from climbing too high or the aircraft from landing at sea level while the cabin was still at 6,000 feet. Advances in technology allow the pilot to simply set the landing elevation and let the automatic controller do the work. When that system fails, problems can occur quickly. Rapid or even explosive decompression at 35,000 feet can render you unconscious in as little as 60 seconds. That time drops to a mere 15 seconds at 43,000 feet. For these reasons each pilot station is equipped with an oxygen mask, and it almost always is a quick-donning style that can be opened and put on with one hand in five seconds. Just as you practice and train for crosswind landings, airline pilots are routinely trained and checked on rapid decompression and emergency descents.

FLYING HIGHER IS almost always better than flying lower. Getting above the weather is always more comfortable than going through it, and taking advantage of jet-stream tailwinds and increased engine performance can save hours of flight time. A pressurized aircraft makes all of this possible. Basic pressurization concepts are included in the Commercial Pilot Practical Test Standards. The pilot must exhibit knowledge of the elements related to pressurization and the physiological hazards associated with high altitude flight and decompression. When discussing pressurization, think of the aircraft as consisting of two sections: pressurized vessel and nonpressurized vessel. The pressurized vessel will generally encompass the passenger cabin and cockpit, as well as the baggage compartment (we don’t want Fido getting hypoxia). This section will be able to hold air under pressure in order to simulate a suitable altitude for comfort, temperature, and oxygen saturation. Most pressurized aircraft operate between 6,000 and 8,000 feet of cabin altitude. This pressure is maintained by using bleed air from some form of a compressor on the aircraft engine (“How It Works: Pressurization,” March 2012 Flight Training). Whether that is a piston-powered, turbocharged engine or a turbine-powered

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Flight Training - July 2012

Table of Contents for the Digital Edition of Flight Training - July 2012

Flight Training - July 2012
President’s Perspective
Right Seat
Letters
Best of Both Worlds
How It Works
Knowledge Test News
After the Checkride
News
Since You Asked
News
Final Exam
Products
ASI News
AOPA Action
Flying Carpet
ENJOY THE VIEW
V IS FOR VELOCITY
TECHNIQUE
Weather
Checkride
Flight Lesson
Year One
Career Advisor
Tech Talk
Is Flying Hard?
Delaying Solo
Are You Positive?
Advertiser Index
Debrief
Flight Training - July 2012 - Flight Training - July 2012
Flight Training - July 2012 - Cover2
Flight Training - July 2012 - 1
Flight Training - July 2012 - 2
Flight Training - July 2012 - 3
Flight Training - July 2012 - President’s Perspective
Flight Training - July 2012 - 5
Flight Training - July 2012 - Right Seat
Flight Training - July 2012 - Letters
Flight Training - July 2012 - 8
Flight Training - July 2012 - 9
Flight Training - July 2012 - Best of Both Worlds
Flight Training - July 2012 - 11
Flight Training - July 2012 - How It Works
Flight Training - July 2012 - Knowledge Test News
Flight Training - July 2012 - After the Checkride
Flight Training - July 2012 - News
Flight Training - July 2012 - Since You Asked
Flight Training - July 2012 - 17
Flight Training - July 2012 - News
Flight Training - July 2012 - 19
Flight Training - July 2012 - Final Exam
Flight Training - July 2012 - Products
Flight Training - July 2012 - ASI News
Flight Training - July 2012 - AOPA Action
Flight Training - July 2012 - 24
Flight Training - July 2012 - 25
Flight Training - July 2012 - Flying Carpet
Flight Training - July 2012 - 27
Flight Training - July 2012 - ENJOY THE VIEW
Flight Training - July 2012 - 29
Flight Training - July 2012 - 30
Flight Training - July 2012 - 31
Flight Training - July 2012 - 32
Flight Training - July 2012 - 33
Flight Training - July 2012 - V IS FOR VELOCITY
Flight Training - July 2012 - 35
Flight Training - July 2012 - 36
Flight Training - July 2012 - 37
Flight Training - July 2012 - TECHNIQUE
Flight Training - July 2012 - 39
Flight Training - July 2012 - Weather
Flight Training - July 2012 - 41
Flight Training - July 2012 - 42
Flight Training - July 2012 - Checkride
Flight Training - July 2012 - Flight Lesson
Flight Training - July 2012 - Year One
Flight Training - July 2012 - Career Advisor
Flight Training - July 2012 - 47
Flight Training - July 2012 - Tech Talk
Flight Training - July 2012 - Is Flying Hard?
Flight Training - July 2012 - Delaying Solo
Flight Training - July 2012 - Are You Positive?
Flight Training - July 2012 - Advertiser Index
Flight Training - July 2012 - 53
Flight Training - July 2012 - 54
Flight Training - July 2012 - 55
Flight Training - July 2012 - Debrief
Flight Training - July 2012 - Cover3
Flight Training - July 2012 - Cover4
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