08/28/2026
The U.S. Navy’s Orca XLUUV recently completed a transit of more than 1,000 nautical miles across the eastern Pacific.
The distance is significant, but from a navigation standpoint, what happened beneath the surface is considerably more interesting.
Once submerged, GPS is no longer available. Orca must maintain an accurate navigation solution while operating for extended periods without a navigation team onboard.
Inertial navigation provides continuity, but INS error accumulates with time. Velocity aiding, depth information, acoustic references, onboard sensors and periodic absolute position updates can all contribute to controlling that error. The difficult part is determining the integrity of those inputs and knowing when the navigation solution requires correction.
On a submarine, people are part of that process. The navigation team evaluates the solution, compares independent sources, recognizes inconsistencies and determines when something no longer makes sense.
Orca has to accomplish much of that through automation.
The Navy has not publicly disclosed the vehicle’s complete navigation architecture or exactly how its position uncertainty was managed during this transit, and that may be the most interesting part of the story.
A 1,000 NM autonomous transit demonstrates more than endurance. It demonstrates the ability to maintain a useful navigation solution across operationally significant distance without a crew continuously evaluating it.
For generations, submariners have worked the problem of maintaining an accurate submerged position without GPS.
Orca adds another variable:
Doing it without the navigator.
