In October 1971, Hafele and Keating flew cesium beam atomic clocks around the world twice on regularly scheduled commercial airline flights, once to the East and once to the West . In this experiment, both gravitational time dilation and kinematic time dilation are significant - and are in fact of comparable magnitude. Their predicted and measured time dilation effects were as follows:

Predicted: Time difference in ns between the ground base clock and the average time registered by the 4 clocks going east and then west.

                      Eastward           Westward

Gravitational  144 +/- 14            179 +/- 18

Kinematic     -184 +/- 18            96 +/- 10

Predicted global   -40 +/- 23            275 +/- 21

Observed:           -59 +/- 10             273 +/- 21

 the gravitational time dilation might be different due to lower flight trajectory in the eastward flight...but somebody should clarify..

Why should the kinematic time dilation be so different in the two directions? In both cases the airplane flew at about the same speed relative to the Earth Surface where the reference atomic clock was located...

1) no idea how these contributions G and K were isolated

2) no idea how the clock on the plane which has larger speed than the clock on Earth can possibly be not dilated but have faster pace in the westward journey and is instead dilated in the eastward.

Thanks to KARE OLAUSSEN to have provided the simple explanation with the SCHW solution.

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