Recently, we flew a first-time client who, unbeknownst to us, had just been released from the Mayo Clinic after having a successful lung operation. When we met the client at the aircraft, he appeared to be in good health and made no mention of his recent medical experience.
However, as we climbed up to our planned cruise altitude of 43,000 feet, we soon learned of the client’s operation as he shared with us that his breathing was labored. Since the air at 8,000 feet is thinner and less dense than air at lower altitudes, we immediately lowered our cabin altitude from 8,000 feet to 3,000 feet by descending to 30,000 feet. We also prepared for a possible emergency diversion to a medical facility, but fortunately the client was able to breathe more freely the lower we descended.
Jet aircraft have the benefit of sophisticated pressurization systems which allow us to fly comfortably as high as 51,000 feet. Generally, most jets can maintain the equivalent of sea level elevation and pressure as the aircraft climbs up through 20,000 feet. Depending upon the system’s capabilities, the cabin pressure then starts to climb slowly at a ratio, or differential, of the outside altitude compared against the cabin’s pressurized altitude. The flight crew is able to manipulate the altitude of the cabin, to a certain extent, by calculating the differential at a particular altitude. Should you find the need to fly at a lower cabin altitude, be sure to discuss this with your flight crew well in advance, as flying at lower altitudes burns significantly more fuel, which could affect your flight plan, requiring refueling along the way.