The NAS-14V2 also worked on the ground - it had multiple modes (astroinertial [default], inertial, airstart and dead reckon). See 10A-17 and Figure 10A-4 in the

The NAS-14V2 also worked on the ground - it had multiple modes (astroinertial [default], inertial, airstart and dead reckon). See 10A-17 and Figure 10A-4 in the manual. If you read the following sections it describes procedures for calibrating the system in the event of a rapid takeoff (where a fix wasn't available), for example the runway heading can be entered as a quick heading fix. It wasn't particularly quick, mind - up to 96 minutes for the full ground procedure. They also talk about calibration in hangars, which is important because you don't want your secret spyplane sat on the apron for satellites to see for over an hour! There are some interesting tidbits in there. The tracker automatically compensates for shockwave and thermal gradients over the sighting window, for example.