Mean sea level:This is determind by observing accurately and precisely the SAE LEVEL at a point over a period of time less than a year,this defines the vertical datum of survey in any locality.Any FRI…
Added by YASIN MALIK at 4:53am on January 17, 2012
I am lead to believe Topcon GPS users may only calibrate for elevation on three, or is it four, control points to establish a localised level datum and that the result is an inclined plane of best fit…
Added by Doug Tarrant at 2:09am on February 10, 2017
Surveying Runway during brief shutdown for new construction of runway lights, Port Authority control was a mess and nothing checked so we had to also re establish site datum being used, Via GPS