Patent ID: 8011447

Claim:
A method of surveying drill holes comprising the steps of: drilling a borehole with a drill string formed by a plurality of drill rods having a drill bit located at a cutting end of the drill string and being driven at least by percussive forces, wherein an inertial survey package is disposed within the drill string at the cutting end and advances with the drill string into the borehole while the drill string is operational to drill the borehole as part of a hole drilling operation, and wherein the survey tool is maintained in a sleeping mode while drilling is undertaken; activating the survey tool once drilling is completed; withdrawing the drill string from the borehole; determining when the drill string is halted during the withdrawing of the drill string from the borehole; and taking position readings from the survey package as withdrawal of the drill string is temporarily halted to remove each drill rod from the drill string in response to determining that the drill string is halted during the withdrawal of the drill string from the borehole.