Suppose crowded airports can be considered a sign Australians are eager to return to the skies. If you frequently engage in long-haul flights, there might even be more extended flight options a few years from now.

Qantas, the Australian airline, has announced that it will commence direct flights from the east coast of Australia to London, UK, by the end of 2025, with a flight time exceeding 19 hours.

In comparison, current flights take 24 hours but involve layovers and shorter segments. So, what changes might occur in the body during longer flight durations? Will it differ from current long-haul flights?

1. Before boarding, don't forget to hydrate. Dehydration is common during long flights, leading to dry throat, nose, and skin on the plane. The longer the flight, the higher the risk of dehydration, primarily due to lower humidity in the cabin than the ground.

This is because most of the air circulating in the cabin comes from outside, with less moisture at high altitudes. Dehydration can also result from not drinking enough water or consuming excessive alcohol (as alcohol is a diuretic, leading to increased fluid loss). Therefore, drinking water before boarding and continuing to hydrate during the flight is essential.

2. Long-duration travel may increase the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE) due to prolonged immobility in the confined aircraft cabin. A stagnant sitting position interferes with venous return in the legs, leading to venous stasis.

Part of a blood clot may break off and migrate to the lungs, causing a pulmonary embolism, which can be life-threatening. Common signs of DVT in the lower limbs include pain or tenderness, swelling, increased skin temperature, redness, or discoloration. Acute symptoms of PE include unexplained shortness of breath, chest pain, coughing, or coughing up blood.

3. Even calm adults can become emotional on a plane, not to mention the presence of crying children. The stress during travel has a more significant impact on mental well-being than one may realize. Flying can also cause physical discomfort, as passengers have minimal personal space in the narrow cabin, creating a sense of confinement. This is why passengers quickly become frustrated with delays or unexpected events during the flight.

4. Of course, jet lag also affects almost everyone except a few individuals. Jet lag occurs when the body's internal time and the local time at the destination are out of sync. The longer the flight, the more likely (but not always) to cross more time zones, especially when traveling eastward.

5. If you frequently engage in long-haul flights, there's a reason to assume that the longer the time spent in the air, the greater the exposure to cosmic radiation. As the name suggests, this is radiation from space, which may increase the risk of cancer and reproductive issues.

We don't know the safe level of radiation exposure. Still, unless you're a frequent flyer, this is generally less likely to be a concern. If you are pregnant or have other problems, it's advisable to consult with a doctor before flying.

6. And let's not forget about COVID-19. Standard preventive measures are still necessary, such as frequent handwashing, wearing masks, and avoiding travel when feeling unwell.

In summary, research on how the human body may react to longer direct flights between Australia and Europe is in the early stages, with Australian teams currently studying this. Until the results are available, advice for long-haul flights remains relatively straightforward: follow the airline's guidelines and, if necessary, consult with a doctor before travel.