When we fly on an airplane, there are countless mechanical processes and safety systems working diligently behind the scenes to ensure a smooth and pleasant journey. From the complex aerodynamic forces that allow massive jets to take wing, to the cutting-edge avionics maintaining precise navigation, modern airliners truly represent feats of modern engineering!
Among the most critical yet perhaps lesser understood functions is cabin pressurization. While relaxing on a Jetbed and cruising at high altitudes, be it in a Bombardier, Cessna, Dassault, Embraer, Gulfstream, Hawker, or Pilatus, thick aircraft skins and pressurized cabins labor to replicate breathable conditions found much closer to sea level.
Today, we want to explore this process further and explain how pressurization impacts air travel. Delving into why aircraft pressurize their interiors, how the system works, and what occurs if it fails offers insight into an integral component that affects every flier’s comfort and well-being.
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Why is an Airplane Pressurized?
One of the primary reasons aircraft cabins are pressurized relates directly to human physiology. As planes climb towards their operational cruise altitudes, often between 30,000-45,000 feet, outside atmospheric pressures and oxygen levels rapidly decrease. However, this doesn’t match what the human body requires to function safely and comfortably. At typical cruising heights, cabin pressures would replicate breathing air found at 16,000-24,000 feet above sea level and these are conditions that can quickly lead to hypoxic effects if uncorrected.
To prevent these issues, standard pressurization maintains a cabin altitude closer to 8,000 feet even when physically much higher according to altimeter readings. At this simulated station, oxygen pressure and partial pressures match levels that comfortably sustain the pilot and passengers without adverse symptoms.
For private jet cabins, which may fly VIP clients or crews for extended periods, recommendations are a slightly lower 6,000 feet maximum pressure differential between interior and exterior. This additional margin helps reduce fatigue over longer sectors and maintains circulation/bodily functions at a healthier baseline. Correct pressurization is thus essential for safe and enjoyable flying at high altitudes.
How Does Cabin Pressure Work?
In order to safely maintain the ideal cabin pressure environment, advanced pressurization mechanisms carefully monitor and control aircraft interior conditions. On large transport aircraft, bleed air is extracted from high-pressure engines stages before combustion, cooled, and pumped into the fuselage through an intricate network of ducts. Within the cabin, an outflow valve precisely regulates the pressure by allowing a calibrated release of air whenever exterior atmospheric pressure decreases during climb.
A computerized auto-control system automatically pilots the valve position to achieve the optimal target cabin differential from sea level. Typically reaching stabilization 8 minutes after takeoff, it then oversees minute adjustments throughout flight. Private jets often utilize virtually identical self-contained pressurization packs independent of engines.
As altitude changes, the system compensates in real-time to ensure flyers experience just 6,000 feet above true cruising height. This sophisticated engineering preserves the cockpit and passenger well-being while permitting flight much closer to the stratosphere. Proper cabin pressurization hence relies on technology to replace what is absent in nature at high flight levels.
As described in the post on “What is ISA in Aviation“, the International Standard Atmosphere (ISA) model established by ICAO helps harmonize our understanding of how factors like temperature and pressure vary with altitude. On commercial aircraft, carefully engineered cabin pressurization systems work diligently to counteract these changes and maintain livable conditions inside the pressurized cabins. However, minor cabin pressure fluctuations still occur that passengers may notice. Being prepared to manage small differences can reinforce safety and comfort.
What Happens When a Plane Loses Cabin Pressure?
While modern aircraft design makes depressurization events exceedingly rare, crews rigorously train in emergency procedures to prepare for this unlikely scenario. If a pressurization failure causes the cabin altitude to rise above safe thresholds, pilot alarms and lights will automatically cue drop-down oxygen masks throughout the plane. These masks are crucial, as without supplemental oxygen, oxygen levels in the bloodstream could fall to dangerous hypoxic levels in mere seconds at typical airline cruising altitudes.
When the warning sounds, all occupants must promptly grab and place their mask over their nose and mouth to activate the emergency oxygen supply. This buys time for the crew to isolate any issues and commence a rapid controlled descent if needed. On large jets, backup oxygen tanks have sufficient capacity for all passengers to temporarily breathe until a safe altitude is regained.
Possible depressurization causes include equipment malfunctions, metal fatigue cracking the fuselage without detection, or structural damage entering the pressure vessel. Having oxygen masks ready for immediate use is therefore absolutely vital, with donning procedures thoroughly practiced throughout the aviation industry.
How To Deal With Cabin Pressure as a Passenger?
Step 1: Use gum or candies to pop your ears.
As described in the post on “What is Density Altitude“, altitude changes during ascent and descent can cause ear discomfort through pressure variations. Chewing gum opens the Eustachian tubes to equalize pressure between the middle ear and ambient air. This alleviates ear pain that may arise from rapid cabin altitude shifts. Sucking hard candies produces a similar effect.
Step 2: Stay hydrated.
The recirculated cabin air in commercial aircraft becomes dry owing to the heat exchanger that cools bleed air entering from engine compressors. This dried environment can further dehydrate tissues during lengthy flights. Drinking sufficient water helps counteract the thinness of high-altitude air by keeping bodily moisture intact. Adequate hydration also benefits equalizing pressures felt in sinus and ear cavities.
Step 3: Stretch or change positions.
As outlined in the post on “what is isa in aviation”, reduced oxygen partial pressure at elevated flight levels lowers oxygen tension within pressurized cabins compared to oxygen levels at sea level pressure. Remaining sedentary for long periods in this thinner air environment can induce minor cramping or stiffness. Walking the cabin and mild stretching reinforces circulation to deliver more oxygenated blood to muscles and prevent tissue tightening.
Step 4: Use nasal saline spray.
Changes in cabin altitude due to normal pressurization cycles can cause ear and sinus pressure discomfort during ascent and descent. Applying a few sprays of saline solution into each nostril helps the body equalize pressure differentials between high and low pressure areas. The saline keeps nasal membranes moist and permeable to aid this transitional process.
Step 5: Use the oxygen masks.
In rare cases of abnormal cabin pressure loss requiring emergency oxygen, masks will automatically drop from the ceiling or side walls. Placing the mask over nose and mouth and breathing normally supplies pressurized oxygen to fulfill our breathing needs should the cabin altitude unexpectedly rise above certified flight levels. Proper donning of masks protects occupants until a safe air pressure is regained.
Step 6: Supplement with breathing exercises.
Controlled inhales and exhales introduce extra pressure shifts within ear canals to break up potential blockages. Yawns and swallows generate these equalizing impulses, as does briefly humming or singing. Supplemental oxygen through masks may also be available if cabin altitude unexpectedly rises beyond certified levels. Proper breathing keeps tissues flexible amidst pressure changes.
Airplanes are pressurized to maintain atmospheric pressures and oxygen levels that are safe for passengers!
Proper preparation and quick remedies help the body acclimate to pressure fluctuations inherent in flying. Commercial aircraft cabin pressurization systems maintain livable atmospheres, but understanding potential impacts of changing ambient air pressure with altitude empowers passengers dealing with any slight pressure differences encountered.
For more information on all things around aviation technology from answers to questions like What is AQP in Aviation to updates on Safety Management Systems in Aviation, check out our blog. And, if you’re looking for an easy and convenient tool that will help you and your crew avoid flight fatigue, explore our fleet of JetBeds to find the one that best suits your aircraft and lifestyle.