A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David C
Date: 2016 Jul 21, 20:48 -0700
I believe that it is possible to separate aircraft accelerations from gravity:
(LINZ = Land Information New Zealand aka Lands And Survey)
"LINZ says that understanding the height of our land is important for understanding how water will flow during a flood or storm. People commonly talk about metres above sea level as a way of describing heights, but sea level can vary at different points around the country. To give scientists and researchers consistency, LINZ has developed a new vertical datum, a reference system based on gravity.
This has been four years in the making and has involved flying the length and breadth of the country with a specially equipped plane for gathering gravity measurements, as gravity can vary from place to place."
For the audo on which this quote is based go to
I have no idea what technology is used and what it cost.