If the only concern was that your GPS receiver could fail, then you could rely on your backup system. Either a second receiver, or some other system. (TACAN, INS, etc.)<p>Their concern seems to be, &quot;What if none of the electronic systems can be trusted?&quot; That wasn&#x27;t as much a concern when the sextant courses were dropped, but they are now, which is why it seems they&#x27;re reinstating them.<p>Curiously, INS (inertial navigation system), which uses gyroscopes, is often turned to as a backup for when GPS can&#x27;t be used, or is otherwise unavailable. (Many guided systems now can use INS as a backup if the GPS signal is jammed.) Most ships have this as well. Presumably this would be an adequate fallback.<p>That being said, if my ship were dead in the water with no electrical power, this seems like a no-brainer.