Some PBF organizations specialize in disaster and emergency preparedness. Their pilots fly surveillance missions, send data back to emergency operations centers, transport emergency workers and supplies, and fly search and rescue missions. Examples include the largest such PBF group, the Civil Air Patrol, and the Emergency Volunteer Air Corps (EVAC). EVAC works to promote the idea that many thousands of general aviation pilots and aircraft can provide lifesaving services following a disaster, and encourages all volunteer pilot groups to organize their pilots to that end. The Air Care Alliance has provided seminars on emergency preparedness conducted by EVAC representatives and others, and now most member PBF organizations have an auxiliary mission of providing relief missions when the need arises. See the ACA site for information about such relief efforts after the 911 attacks, hurricanes such as Katrina, and earthquakes such as Loma Prieta and Haiti.