If you’re after a quick answer, it’s yes—they do!
Modern airliners fly at about 650 mph, roughly 11 km above the Earth’s surface, where outside temperatures can drop to -70°C. Thanks to reliable engineering, we can still watch films, eat, drink, and even sleep in relative comfort. Two key factors that greatly influence fatigue and hydration on a flight are the cabin air supply and the cabin altitude.
Cabin Air and Humidity
Because the air pressure at high altitude is very low, there isn’t enough oxygen in the outside air for us to breathe. Aircraft can’t simply scoop in air from outside; instead, they draw high-pressure air from the engines (known as “bleed air”), cool it, and then supply it to the cabin. Although this solves the pressure issue, it results in very low humidity—often around 2–3%—whereas humans generally prefer 40–60%.
The only commercial airliner that does things differently is the Boeing 787 Dreamliner. Rather than relying on engine bleed air, it processes outside air through an electric compressor system, boosting cabin humidity to about 15%—noticeably more comfortable.
Cabin Altitude
Once we have a pressurised air source, the next step is to ensure the cabin environment remains comfortable for passengers. Without a proper pressurisation system, humans would have only about 15 seconds of useful consciousness at 38,000 feet—not ideal for reaching your destination! Pressurising an aircraft is much like inflating a balloon: as you add air, the pressure rises, and you certainly don’t want it to pop. To prevent this, engineers designed an adjustable valve at the rear of the fuselage that allows the aircraft to regulate its internal (cabin) pressure as it climbs and descends.
Once airborne, the cabin is typically pressurised to the equivalent of around 8,000 feet. This is similar to being on a mountain, where your body must work harder due to slightly lower oxygen levels. However, with the advent of composite materials in aircraft such as the Boeing 787 and Airbus A350, it’s possible to reduce cabin altitude to around 6,000 feet, often leaving passengers feeling less exhausted and dehydrated.
Which Aircraft Come Out on Top?
Overall, the Boeing 787 is considered the top choice for in-flight comfort because you benefit from both improved humidity and a lower cabin altitude. In second place is the Airbus A350, which offers a lower cabin altitude but not the same improvement in humidity. Of course, you might not always get to choose which aircraft you fly on, but it’s useful to know that dehydration and stress levels can vary significantly between different types. At the very least, you can prepare accordingly for your journey.