Permanent Echo Radar signals reflected from fixed objects on the earth’s surface; e.g., buildings, towers, terrain. Permanent echoes are distinguished from “ground clutter” by being definable locations rather than large areas. Under certain conditions they may be used to check radar alignment.

Aero Linx: The Airline Pilot's Historical Society The Airline Pilot's Historical Society is a non-profit, charitable foundation whose purpose is to educate through the preservation of aircraft parts and components. What money we raise goes either to educational projects, or to children's hospitals and organizations that specialize in the needs of children. We are all volunteers...we have no paid employees. Founded in 1997.

"For those reasons, a key measure of success is not, 'Did we provide the most flights possible?' but 'Did we provide the most comfortable flights possible?'—for instance, by avoiding stressful layovers and preventing long drives to and from the airport. Our mission is to provide hope to these families, and how we deliver that hope matters." Source: Miracle Flights CEO Mark E. Brown, noting that the nation's leading medical flight provider, Miracle Flights, concluded March with 640 free flights provided to families of children battling rare and life-threatening illnesses, according to the Las Vegas–based charity. Established in 1985, Miracle Flights arranges commercial airline flights at no cost to help children with complex med