Airborne Technology

Unravelling Geological Complexities

XDS VLF-EM Technology

The cornerstone of the Structural Multi-View Airborne Geophysical Surveying System is Terraquest’s advanced and proprietary XDS VLF-EM structural Mapping tool. This technology has been developed to map structure and help Geologists to solve structural problems. XDS Compliments other EM systems which are designed to identify and delineate specific targets. The XDS VLF-EM technology maps fine grain, low conductivity and more disseminated structures, providing a more comprehensive database for Geologists trying to sort out geological complexities. Consequently the technology is suited to mapping structure related to any exploration commodity.

Data is gathered with three different coils on the x, y and z axes. Presenting the data on three separate maps produces much cleaner structural profiles compared to a single amalgamated data. XDS VLF-EM acquires data in broadband mode (typically 22-26 KHz) thus it is not sensitive to geological strike and the availability of a particular transmitter.



The measurement of the earth’s horizontal magnetic gradient is particularly useful for detecting near surface magnetic sources. Exceptionally good gradiometer data can be gathered by flying slowly at low altitudes. This is an ideal tool for kimberlite exploration. Terraquest was one of the first survey contractors to operate a commercial horizontal gradient system as early as 1989.


Primary advantage is in improving the gridding and contouring of data for enhanced resolution. Measuring Horizontal Gradient data is useful in identifying:

  • The precise location of small anomalies between flight lines.
  • The precise location of contacts, dykes and faults.
  • “Magnetic axis” within many of the magnetic units.
  • The indication of the dip of some magnetic units
  • The discrimination between cultural and small geological sources such as Kimberlite.
Horizontal Gradient Vectors show the real location as opposed to the single sensor TMI along flight path.

Helicopter Magnetometer/Digital Radiometric Survey System

Terraquest has developed a portable light weight, high resolution heli-mag system that can be easily installed on B206L-iii/iv or AStar helicopters.

Features include:

  • 24′ Kevlar boom mounted on the airframe with the mag sensor positioned 8 ft beyond the perimeter of the main rotor blades.
  • Precise GPS navigation and pilot guidance system
  • Cesium sensor, radar altimeter, digital colour video
  • Light weight: < 100lbs
  • Data Acquisition System, can be buckled in with seat belts
  • Digital radiometrics


  • Provides excellent anomaly resolution using high definition magnetics
  • Cost effective operation because of lower transportation and installation costs
  • In-field data processing available for fast turn around

Ancillary Support Equipment

Ancillary support equipment includes a tri-axial fluxgate magnetometer, digital video camera, CD recorder, radar altimeter, barometric altimeter, GPS receiver, GPS receiver with a real-time correction service and a navigation system. The navigation system is comprised of a left/right indicator for the pilot and a screen showing the survey area, planned flight lines, and the real time flight path. All data is collected and stored by the data acquisition system for processing in the field.

100 Meter Drape Airborne Survey

Pre-Planned Drape Flying

Pre-planned drape flight operations significantly enhance the quality of the data set being gathered. It is most suitable for higher altitudes and/or rough terrain. It ensures good line to line correlation including accurate intersections of the traverse and tie lines. Knowing the aircraft’s precise position and altitude contributes significantly to the quality of the data set when levelled and lends to higher resolution for future modeling.