Women can serve in all roles in the US Air Force (including combat female pilots). Today, many women are training to become pilots, both in the military and civilian sectors. Some physical requirements for women differ from those of their male counterparts and vary depending on the role. Flying airplanes is just one of many jobs in the Air Force; of the total Air Force 689,000 personnel, only a tiny fraction, around 4%, are pilots. As it happens, the US Air Force has the highest percentage of women of any service branch (19% in 2016, according to the Air Force).