(er’ ō mag net, ik) Involving magnetic measurements made from an aircraft. Data are typically sampled at 6–10 m intervals. A fixed-wing survey uses sensors mounted on the aircraft and sometimes a magnetometer is towed in a bird 50–100 m below and behind the aircraft. Sensors are also mounted in helicopters. Surveys are usually flown at constant elevation above sea level, but sometimes in drape surveys (q.v.) they are flown at a constant elevation above the somewhat-smoothed surface.