Duck - not to worry too much about the "what", most programs don't work much of the time. Many of the alleged navigation programs are overrated. This from today's news >
> and that's after 2 other NATO submarines crashed into each other in the middle of the Atlantic, another US sub demolished a Japanese fishing boat while coming to the surface in the middle of the Pacific, yet another crashed into some underwater mountaintop, also in the Pacific, and on, and on.
You'd think with all the satellites, onboard radars, other onboard and onshore equipment, listening devices, just plain eyesight, something would work, but nah!