An aeroplane's cabin pressure when flying at a high altitude is-

The pressure inside a plane's cabin when it's flying at a higher altitude is higher than the outside pressure.

Despite the fact that airline cabins are pressurized, cabin air pressure is lower at cruising altitude than it is at sea level. In the normal cruising altitude range 11,000 -12200 m (36 000-40 000 feet).

At this altitude, the cabin air pressure equals the outside air pressure 1800-2400 m  (6000-8000 feet) higher than sea level

As a result, the blood absorbs less oxygen (hypoxia), and the body's gases increase. Healthy passengers may be able to tolerate the effects of lower cabin air pressure.

During the climb the cabin pressure is slowly decreased. While a typical passenger jet may climb at speeds in excess of 2000 feet per minute, the cabin pressure will decrease at an equivalent rate of climb rarely exceeding 500 feet per minute