Note – I put in positive values for Latitude in this calculator – I should have used negative values however this has zero effect on the results. The answers were the same. Just pointing it out for correctness.
Thank you to Walter for his excellent calculator which you can find here.
This video demonstrates the Eötvös effect which results in variations in weight depending on your direction of travel – going East the weight is lighter than when traveling West.
This is due to the Centrifugal force generated by adding Earth’s rotation to the motion of the aircraft. Going East the speeds are added. Going West the aircraft speed is subtracted from the Earth’s rotation.
When flying East this weight averaged 495 grams on the scales.
Flying West the average is about 499 grams.
As explained in the video the effect of air pressure / density is negated by the fact that both experiments were done in pressurized aircraft with similar cabin pressure.
Most of the effect of altitude is similarly negated as flight altitudes were both above 30,000 ft.
The major factor affecting the difference in weight seen on the scales is the direction of the aircraft. Lighter weight going East, and about 4 grams heavier going West.