To improve mineral exploration success, there is an industrywide consensus on the need to increase the ‘discovery space’ by exploring under cover and to greater depths. Over the last decade, airborne electromagnetic (AEM) systems have evolved with ever higher moments, and sensor calibration and post acquisition processing technologies have improved data quality significantly. As an alternative to conventional AEM, the Z-axis Tipper Electromagnetic (ZTEM) and Airborne Magnetic Tensor (AirMt) systems were developed to measure the transfer functions of audio frequency natural electromagnetic sources from airborne platforms. The ZTEM system measures tipper transfer functions, and the AirMt system measures the rotational invariant of the transfer functions. Ancillary data measured by both systems include radar altimeter, receiver altitude, GPS elevation, and total magnetic intensity. For both ZTEM and AirMt, data are typically measured from 30 Hz to 720 Hz, giving detection depths to 1 km or more, depending on the terrain conductivity. This makes it a practical method for mapping large-scale geological structures. This paper discusses technical specifi cations of both the ZTEM and AirMt systems, including data processing and interpretation.