Geodetic Data Collection Techniques - Geodesy: Introduction to Geodetic Datum and Geodetic Systems - page 62

Fig. 2.21 Airborne gravity
measurement
An airborne gravity measurement test was first conducted in 1958. The precision
of navigation was rather low and the 10 mGal accuracy in the vertical disturbing
accelerations of the aircraft was difficult to maintain, so until the late 1970s the
technology of airborne gravimetry had virtually been in a state of stagnation. The
advent of GPS, particularly implementation of the centimeter-level kinematic
differential GPS, enabled the separation of gravitational effects with a precision
of a few milligals. There are two main categories in airborne gravimetry; namely,
scalar gravimetry and vector gravimetry. Scalar gravimetry can only determine the
acceleration due to gravity, whereas vector gravimetry can measure both gravity
anomalies and deflection of the vertical. Currently, the technology of airborne
vector gravimetry is still undergoing research and development and is being used
in some routine operations.
Fundamentals of Airborne Gravimetry
The basic principle of airborne gravimetry is to use the airborne gravimeter on the
aircraft to determine the gravitational variations of the flight profile relative to the
surface reference gravity point and compute the non-gravitational accelerations and
corrections to disturbance. Through filtering and data processing, the results can be
obtained and then, in the downward continuation approach, the gravity value at a