Recently, Qantas, the Australian Airline announced that from late 2025, it will fly passengers on non-stop flights from Australia's east coast to London that would see you in the air for more than 19 hours in one stretch.
In the year 2021, Air India made aviation history by flying nonstop for more than 17 hours over the North Pole to complete the longest air route in the world, connecting Bengaluru and San Francisco. This flight covered a distance of roughly 16,000 kilometres.
In a few years, the long haul will become even longer. So, if you're taking a regular long-haul flight, the advice is relatively simple. Make sure to follow the advice the airlines give you, and see your general physician before your journey if necessary.
Here’s what happens to your body on a long-haul flight:
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You can become dehydrated
Dehydration is common on long-haul flights. The longer the flight, the greater the risk of dehydration.
That’s because there are low levels of humidity in the cabin compared with what you’d expect on the ground. This is mostly because a lot of the air circulating through the cabin is drawn from the outside, and there’s not a lot of moisture in the air at high altitudes.
You also risk dehydration by not drinking enough water or by drinking too much alcohol (alcohol results in an increase in fluid loss).
So drink water before you jump on the plane. During the flight, you’ll also need to drink more water than you usually would.
You could develop blood clots
Blood clots, associated with being immobile for long periods, are usually a big concern for passengers. These include clots that form in the leg (deep vein thrombosis or DVT) that can travel to the lung (where it's known as a pulmonary embolism).
If you don't move around on the plane, and the more of the following risk factors you have, the greater the chance of blood clots developing:
Older age
Obesity
Previous history or a family history of clots
Certain types of clotting disorders
Cancer
Recent immobilisation or surgery
Pregnancy or recently given birth
Hormone replacement therapy or oral contraceptive pill.
The cabin can play havoc with your ears, sinuses and gut
As the cabin pressure changes, the gas in our bodies reacts accordingly. It expands as the aircraft climbs and the pressure decreases, and the opposite occurs as we descend. This can result in common issues such as earaches, headaches, and gut problems, among many others.
You might get earaches when the air pressure on either side of your eardrum is different, placing pressure on the eardrum. While headaches can be caused by expanding air trapped in your sinuses
Your sense of taste is diminished
A study by Lufthansa, found that cabin pressurization and bone-dry, in-flight air evaporate nasal mucus, causing our sinus membranes to swell. Combined, this makes it more difficult to discern the subtle scents that are critical to our sense of taste. In particular, our sense of salty and sweet dulls by up to 30 percent at altitude. It’s also the reason why big, bold spices are often used to punch-up the flavor profiles of airline food.
You are sleepy due to oxygen deprivation
Modern airplane cabins are designed to simulate an elevation of 6,000-8,000 feet. This can result in dizziness, sleepiness (or sleeplessness in some individuals), and an overall dulling of mental acuity.
The lack of movement, especially on long-haul flights, only exacerbates the effect by slowing the flow of blood (and therefore oxygen) throughout your body. This is all the more reason why it’s critical to get up and walk around every hour or so while airborne.
Dry skin
That same recirculated air that dries out your nasal cavity is brutal on your skin too. Thankfully, body lotions and balms can combat this. It’s also why airline employees who fly frequently double down on their water consumption while on the job.
Jet lag
Then there's jet lag, which is a stranger to few of us. This is a disconnect between the time your body thinks it is and the time by the clock, as you cross time zones. Longer flights mean you are more likely (but not always) to cross more time zones. Jet lag will usually become more problematic when you cross three or more, especially if you're travelling east.
