Airborne electromagnetic methods are characterized in detail. A classification of airborne electromagnetic systems is presented. Modern active frequency-domain, time-domain and combined electromagnetic systems, and electromagnetic passive systems are discussed. The paper demonstrates specific aspects to be considered in the development and operation of airborne electromagnetic systems. The paper discusses aspects of processing of signals measured onboard, and techniques to improve system susceptibility, mobility and reliability. Survey results are presented. The paper shows what kind of problems can be effectively resolved today using airborne electromagnetic surveys.