My friend from college was a navigator on a 4 man crew aircraft called the A-6 I believe. Literally his only function in life was to be able to navigate the plane back in case the GPS failed (using maps and a compass and what ever else). So to combat boredom he would take his laptop up on every flight and watch movies and bullshit with the rest of the crew.
The P-3 Orion has a periscopic sextant for celestial navigation, in case the GPS and inertial nav both fail. Granted, the former wasn't around when the plane was designed, but the Navy keeps them on the aircraft and keeps the navigators trained in their usage.
Your friend's bird, particularly if he was in recently, was an EA-6B Prowler, the electronic warfare variant of the A-6.
