Cabin Air Pressure During Flight?

Question

I flew from Guangzhou (China) to Sydney last week and I was still suffering the light residual effects of a cold. The trip was a 9 hour nightmare as I had strong sinus pain and right eye pain from the time we reached our flying altitude until landing in Sydney when the pain promptly disappeared. I put this down to cabin pressure but I always thought cabin pressure in high altitude flying was set the same as that at ground level but obviously not. Does anyone know the prescribed PSI cabin pressure in flight and how does this compare to ground level pressure?

Answer 1

8000feet  or less.

Answer 2

This happens if youre sinsus cavities are blocked!...and you dont always have to have a cold to get blocked sinsuses!...slight changes in pressure are almost certain to happen as the plane ascends and descends on route...and the trapped air in youre sinsus will expand and contract creating pain!...usually the cabin crew have a "sniffer wotsit" that they will give you if they notice you are having trouble...I always carry a decongestant nasal wotsit on board and use as required...I often suffer from this 'exploding head feeling'...especially on descending before landing!...even though i dont have a cold...so be prepared next time!...

Answer 3

Here...

Since the plane is pressurized, when you go up in the sky, you do not experience pressure differences.  The outside pressure is getting lighter, but inside it is still the same.  Why are my ears popping?  While the pilots pump or extract air from the cabin to set the airplane at Colorado's elevation.  If you took off from Colorado... you would not experience pressure differences, or ears popping.

Answer 4

Approx. 8,000 feet.

Answer 5

It is not recommended to fly when suffering from a cold or sinus problems as effects such as you described can occur. They happen when the cabin is being pressurized for the comfort and safety of the passengers and crew. The cabin pressure is approximately 8psi at altitude.

Answer 6

well i work for an air line  ok so i can tell you that the cabin presure only changes when the doors are fuley closed and the plane motors are running other wise the is no difference till then... i i helped..

Answer 7

The cabin pressure on an airliner above 10,000 feet is like standing on a mountain at a lower altitude.  By the time you reach 25,000 feet, the cabin altitude, as it is called, will be like standing outdoors on a mountain at about 8,000 feet.  That is definitely enough to affect your sinuses.

Cabin altitude is not allowed to be higher than 8,000 feet under normal operating conditions.

Answer 8

That's where most people are wrong air pressure is usually set between 6,000 and 8,000 ft PSI this increases as you climb and decreses as you descend

Answer 9

Current FAA regulations require that cabin air pressure must be no lower than the air pressure that naturally occurs at 8,000 feet.

Regulations specify a cabin pressure not lower than 750 hPa but it is not known whether this standard is met. This knowledge is important in determining the hazards of commercial flight for patients and the validity of current flight simulation tests.

Methods:  Using a wrist-watch recording altimeter, cabin pressure was recorded at 60 s intervals on 45 flights in Boeing 747–400 aircraft with three airlines. A log was kept of aircraft altitude using the in-flight display. Change in cabin pressure during flight, relationship between aircraft altitude and cabin pressure and proportion of flight time with cabin pressure approaching the minimum specified by regulation were determined.

Results:  Flight duration averaged 10 h. Average cabin pressure during flight was 846 hPa. There was a linear fall in cabin pressure as the aircraft cruising altitude increased. At 10 300 m (34 000 ft) cabin pressure was 843 hPa and changed 8 hPa for every 300 m (1000 ft) change in aircraft altitude (r2 = 0.993; P < 0.001). Lowest cabin pressure was 792 hPa at 12 200 m (40 000 ft) but during only 2% of flight time was cabin pressure less than 800 hPa.

Conclusions  Cabin pressure is determined only by the engineering of the aircraft and its altitude and in the present study was always higher than required by regulation. Current fitness-to-fly evaluations simulate cabin conditions that passengers will not experience on these aircraft. There may be increased risks to patients should new or older aircraft operate nearer to the present minimum standard.

Answer 10

Aircraft that routinely fly above 3000 m (10,000 ft) are generally equipped with an oxygen system fed through masks or canulas (typically for smaller aircraft), or are pressurized by an Environmental Control System (ECS) using air provided by compressors or bleed air. Bleed air extracted from the engines is compressively heated and extracted at approximately 200 °C (392 °F) and then cooled by passing it through a heat exchanger and air cycle machine (commonly referred to by aircrews and mechanics as 'the packs system').

Most modern commercial aircraft today have a dual channel electronic controller for maintaining pressurization along with a manual back-up system. These systems maintain air pressure equivalent to 2,500 m (8,000 ft) or fewer, even during flight at altitudes above 13,000 m (43,000 ft). Aircraft have a positive pressure relief valve in the event of excessive pressure in the cabin. This is to protect the aircraft structure from excessive loading. Normally the maximum pressure differential between the cabin and the outside ambient air is between 7.5 and 8 psi (51.7 and 55.2). If the cabin were maintained at sea level pressurization and then flown to 35,000 feet (10.7 km) or more, the pressurization differential would be greater than 9 psi and the structural life of the airplane would be limited.

The traditional method of bleed air extraction from the engine comes at the expense of powerplant efficiency. Some aircraft such as the Boeing 787 are using electric compressors to provide pressurization. This allows greater propulsive efficiency.

As the airplane pressurizes and decompresses, some passengers will experience discomfort as trapped gasses within their bodies expand or contract in response to the changing cabin pressure. The most common problems occur with gas trapped in the gastrointestinal tract, the middle ear and the paranasal sinuses. Note that in a pressurized aircraft, these effects are not due directly to climb and descent, but to changes in the pressure maintained inside the aircraft.

It is always an emergency if a pressurized aircraft suffers a pressurization failure above 3000 m (10,000 ft). If this occurs, the pilot must immediately place the plane in an emergency descent and activate oxygen masks for everyone aboard.

In most passenger jet aircraft (such as the Boeing 737) passenger oxygen masks are automatically deployed if the cabin pressure drops below an equivalent altitude of 14,000 feet

Answer 11

http://en.wikipedia.org/wiki/Cabin_press...