At least nine fatal military flights were caused by the pilot having to pee during the flight. Military pilots used to have to unzip their flight suits and pee into a bag called a "piddle pad." This was especially difficult for women, who often would refrain from drinking water before a flight, even though dehydration can dramatically affect vision and reaction time. As a result, the US Air Force is developing a new technology that involves a pad for women, and a cup for men attached to a tube through a special pair of underwear, which will pull their pee through the tube to a collection bag.