10. Emergency Blanket
Whether you survive a plane crash or end up using your emergency blanket later on, this is definitely one item that you want to keep in your carry-on.
Although the blanket folds out large enough to provide you with shelter and reduce heat loss, it is extremely lightweight and folds up into a square that is smaller than the palm of your hand. As an added bonus, the Space brand emergency blanket has a reflective side, and this can be instrumental in attracting attention if the plane crashes or you get lost in the woods.