Ring-laser INS still have a drift of a few kilometres per hour. To keep their respective INS in-check, Tomahawk looks down and performs terrain-comparison wher

Ring-laser INS still have a drift of a few kilometres per hour. To keep their respective INS in-check, Tomahawk looks down and performs terrain-comparison whereas Trident looks up and does stellar nav... The Kearfott Mk 6 that is used by Trident is the successor a line of stellar nav units they produced for the Navajo, SR-71, Hound Dog and FB-111. And probably a bunch of others I've forgotten. The early models used a sheath of acetate star-chart sheets in a mechanical loader to perform the matching operation!