In many Middle Eastern countries, showing someone the bottom of your foot or shoe is considered very rude, so American military personnel stationed in the Middle East are instructed to keep their feet inside helicopters when flying low. Why is this instruction needed?

This instruction is needed inorder not to show disrespect to the cultures and traditions, towards the people living in Middle Eastern countries.

Explanation:

Many Mddle Eastern countries held on to strong cultural values and traditions over a long period of time. This is also greatly influenced by their religious inclination.

For example, it is considered rude and disgusting to eat with your left hand because it is the hand that was used in cleaning your self after visiting the toilet. Likewise, the foot of every individual. Due to the fact that it touches the ground (considered dirty by all standard), they believe that, it is a sign of disrespect to show for someone to show the soles of his feet.

That is why, it is advisible to take caution regarding to this. Respect towards culture is an integral part of the Middle Easternian people and if it means that, the only way to show respect by the American militaries should keep their feet inside the helicopter while flying, then so be it.