Geological Survey of India (GSI) Twin Otter equipped with a high sensitivity Cesium magnetometer and a multi-channel gamma ray spectrometer. Aircraft are conducting airborne surveys over the initial Obvious Geological Potential (OGP) areas of India comprising of 814,861 sq. km. These airborne surveys are part of the National Airborne Geophysical Mapping Programme to locate oil & gas, gold, minerals and diamonds.