During World War I, the aircraft was put into actual combat. At that time, the plane was fully open, which means that there was no glass cover in the cockpit and people could only wear glasses. In combat, a person's head must be twisted in all directions to observe the movement of enemy and friendly aircraft. But when doing so, the cold air at high altitude will pour into the chest from the collar at the neck, making the chest catch cold. Under normal circumstances, you will catch a cold and even cause pneumonia.

In this case, wearing a scarf will solve the problem.

For details, please refer to Jean Reno's explanation in Heroes in Air Combat.

At that time, plane fighting was considered as a knight duel in the air, so everyone was talking about knight style. The plane was shot down, that is, the knight lost his weapon and could not continue fighting. The parachute is designed to be white to indicate this situation. By the way, it says surrender. When the pilot landed on the ground, he also needed something to identify him. The white scarf around the neck has become a good symbol.