As KaleunMarco says above, plus the hand-drawn oval is your current selection, as you've probably surmised. The inner half-cirlce is active sonar, the Pacman 3/4 circle is the passive hydrophone, the inner larger circle is probably visual, and the outer circle is probably radar. The IJN used huge binoculars that pulled in quite a bit more light than the USN thought practically possible, plus the IJN trained in night maneuvers, the USN did not, hence the discrepancies in battle prep and results off Guadalcanal (and Rabaul).
The USN generally used binox like the Japanese officer has in his hands there... Imagine them being able to "see" your sub rather easily from 10nm at night... lol
One of the things about airplanes in the Stock game, is that they have varying skill levels set, from Poor to Veteran, and the lower in skill they are, the worse they fly, but even if a person sets the airplanes to fly at the Elite setting, they are still dumber than a box of rocks when it comes to terrain. The game "defaults" to flying planes at a 500m altitude, and you might notice that the game has a LOT of land masses that exceed that height. The airplanes do not know to increase their altitude, nor avoid by steerage, and thus either "stall" when attempting to slow down, or just outright crash into land masses, especially if attacking ships nearby. Airplanes in the game also do NOT dogfight...
A little thing about "Survivors" also, in that you see a blue "box" for Allied aircrew, and a red box for Axis. You cannot pickup the Axis crews. You might also notice that if you zoom-in too close on the Allied or Axis boxes, that they will disappear at a certain zoom level, unless you are within visual range of them, which is generally roughly 900m or less, depending upon sea state and other visibility factors. As KM says, you have to get within roughly 400-500m to be able to pick them up IF you are going slow enough. It is usually easiest to be going Ahead 1/3, or set the knot meter to 2 knots, then call for All Stop as you get to them. If you come at them bow-on, you will have less wave induced motion to your boat, than a side aspect pickup. You also need a crew member to say "Ship spotted", which indicates they have visual on the survivor. You could then use the NavMap and "see" the survivor icon when you zoom in closer now. Lastly, the survivors will eventually drift off and / or "sink" and disappear, especially shotdown pilots. The game doesn't want to be bothered "tracking" them forever... "Survivors" set as an objective, on the other hand, generally have a longer "life"...