Why is the round-trip time of the flight different?

By Guangyao Q

First, the difference of the round-trip time of the flight does not under the influence of the Earth's revolution, which is one of the most common concerns.

The wind is a main influence of the flight time. For instance, the flight, which is from Beijing to London, is a good example because most of the flight is in the westerlies. People can see the truths, which was mentioned in the last sentence, from the two maps below.

Flight from Beijing to London

The map of global atmospheric circulation

Is wind so matter?

Yes, it is matter. Take the same example. The flight, which is from Beijing to London, has the direct distance 8163 kilometer. Check the wind speed of the westerlies. The wind speed is around 130 km/hr at the altitude of 10,000 meters.

From Beijing to London:
8163 ÷ (800+130) ≈ 8.8 hr

From London to Beijing
8163 ÷ (850-130) ≈ 11.3 hr

There is 2.5 hours difference for the round-trip. This is only a approximation, the real situation is more complex. It is not good enough to be see as an reference but is till good enough to show the strong influence of the wind.

Obviously, compare to wind, the speed of the cruising and the Earth's circulation influent the difference of the round-trip time of the flight so little, which can be ignored.

Thanks for reading.

References:  AVIATION WEATHER CENTER. (n.d.). Retrieved March 28, 2016, from https://www.aviationweather.gov/products/nws/winds/ 

 Atmospheric circulation. (n.d.). Retrieved March 28, 2016, from https://en.wikipedia.org/wiki/Atmospheric_circulation

 

 Distance from London Heathrow Airport (LHR) to Beijing Capital International Airport (PEK). (n.d.). Retrieved March 28, 2016, from http://www.airmilescalculator.com/distance/lhr-to-pek/