Why Do Most Planes Fly at Night?
Most planes don't exclusively fly at night; many flights operate around the clock. However, a significant portion of flights, particularly cargo and some long-haul passenger flights, do operate at night for several key reasons.
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Reduced Air Traffic: As noted in a Quora discussion (https://www.quora.com/Why-do-planes-typically-not-take-off-at-night-Would-it-be-more-beneficial-for-them-to-take-off-during-times-of-less-wind-and-air-traffic), nighttime flights experience less air traffic congestion, leading to smoother and more efficient journeys. This is beneficial for both passenger and cargo flights.
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Cooler Temperatures: Cooler nighttime temperatures, as highlighted on Aviation Stack Exchange (https://aviation.stackexchange.com/questions/42724/why-do-some-companies-perform-their-freight-flights-only-during-the-night), improve aircraft fuel efficiency. Less dense air requires less energy for the aircraft to maintain altitude. This is a significant advantage for cargo flights.
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Smoother Flights: Less turbulence is often encountered at night due to the absence of the sun's heat causing air currents irregularities ([Less Turbulence](Less Turbulence)). This results in a more comfortable flight for passengers.
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Optimized Scheduling: Many long-distance flights are scheduled overnight to better accommodate time zones and crew scheduling, as discussed on Physics Forums (https://www.physicsforums.com/threads/why-are-most-long-distance-flights-scheduled-overnight.1059727/). This allows passengers to arrive at their destination during the daytime while optimizing flight crew duty hours.
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Cargo Operations: A significant portion of freight flights utilize nighttime hours as airports are less busy, and the above advantages related to temperature and air traffic impact efficiency and profitability. As noted in several sources, planes continue to operate throughout the night to meet shipping demands. (https://calaero.edu/learn-to-fly/night-flying/what-do-pilots-see-when-flying-at-night/)
Conclusion
Night flying isn't the norm for all planes, but it's a common practice for several reasons that primarily benefit efficiency, cost-effectiveness, and passenger comfort, particularly for long-haul flights and freight operations.
