Why did pilots wear silk scarves during World War 1?

Answer 1

Three reasons:

1. To keep warm - the wind whipping around the head and shoulders worked its way under the leather flying jacket.

2. To prevent the leather flying jacket from chafing the neck.

3. To wipe engine grease from the goggles.

Answer 2

You really had to know fighter pilots to understand this, but fighter pilots of that period tended to see themselves as 'Knights of the air', flamboyant warriors like medieval knights. -The silk scarf was their 'pennant'

Answer 3

I'm guessing to protect them from strong winds while they flew around