If you’ve ever scanned the globe on flight-tracking app Flightradar24, you’ve probably noticed a few things: airplane “highways” across the Atlantic, high-altitude balloons from Project Loon, and a big gap in air traffic over Tibet. Well, maybe not that last one. But if you pan over to Tibet, you’ll see that the gap is there — and there’s a perfectly logical reason why.
The Tibetan Plateau comprises an area of approximately 965,000 square miles, or just shy of four times the size of Texas, according to NASA and the U.S. Geological Survey. Peeking at Flightradar24, you can typically see planes flying in neat and orderly paths to the north and south of this massive region, but not right through it. That’s because this is one of the highest areas on Earth, with an average elevation of about 14,800 feet. In fact, it includes numerous major mountain ranges, including the Himalayas, home to the world’s tallest mountain, Mount Everest. This exceptionally tall section of Earth has certainly earned its nickname of “the roof of the world.”
Now, you’re probably thinking that planes fly well above 14,800 feet at cruising altitude. And that’s true — cruising altitude is usually between 30,000 and 42,000 feet. So why does the Tibetan Plateau’s elevation affect flights? It all comes down to oxygen levels. If a plane were to experience decompression at cruising altitude, the oxygen masks would deploy, and the captain would descend rapidly to an altitude with more oxygen — ideally below 10,000 feet. (For a point of reference, plane cabins are typically pressurized to about 8,000 feet for comfort.) Given the average elevation of the Tibetan Plateau, descending that low isn’t usually an option, which could spell trouble for any plane experiencing difficulties. So for safety reasons, many airlines choose to avoid flying in this region.
A secondary reason is that mountains create turbulence. You’ve probably experienced a few bumps in the air as you’re flying over the Rocky Mountains on a transcontinental flight — now imagine that going on, and on, and on as you fly across the entirety of the Tibetan Plateau. It simply wouldn’t be comfortable for everyone onboard.
Now, there are five major airports in Tibet, so not all airlines avoid the region entirely. But unless Tibet is your final destination, your flight is most likely going to skirt around the Tibetan Plateau. But hey, that means you’ll get great mountain views as you fly by!