There is also, however, a vast difference between seven and forty kilometers. If the poster was suggesting we bump spotting out to fifteen I'd say it's a reasonable but unlikely to be implemented request. Suggesting 40k is realistic is almost laughable for anyone who flies in real life. Spotting a the equivalent of a minivan at 24 miles (for us Yanks) in even a slightly occluded sky is nearly impossible and in a clear crisp winters sky is unlikely for anyone other than the most gifted. The game handles spotting, with technical considerations, within reason and simulates the average pilot's abilities within those parameters.
I believe the guy that he can see a big balloon in an Arizona Sky at about 40 km distance. I on purpose didn't suggest a "suitable" detection range myself, as IMHO those detection ranges vary tremendously betwen equally eyesighted people. Having a good eyesight, I consider 20 km are a *very* good range to spot planes of the size of a Spitfire. The casual eye (light GA plane passengers) won't see planes farther than 1 km and usually only see them shoudl you have to make an evasive maneuver. I don't really think that the given 10 km is an unreasonable range. Look up at an airliner at cruising altitude. With good vision, you can see the plane very well ahead of the contrails. Imagine the plane being 1/4 of the size. I'm certain that poor window/canopy quality will not let you see the aircraft. Any sort of weather will do so too (unless, as said you are in a climate like Arizona etc.). Detection range should vary depending on athmosphere, as it does IRL. Up at 10 km altitude, you can se very far. 1000 meters above London, sometimes you're happy to see your co-pilot. It's not just clouds, but also humidity.
What I think is more lacking is that added part of contrast that make a plane way easier to track IRL than on the screen. The flat colors in DCS world i find rather appaling in terms of seeing other planes. I find BoS is doing a bit better in that. Still, planes should appear at a given distance in correlation to the athmosphere (also depending on altitude) and when they appear, they should appear *on all screens*, not just on 4k monitors first.
What we have here, that the "pros" see other aircraft as soon as they enter the player bubble is not something that was common back then (and still isn't! Planes still just keep on ramming themselves in mid-air because the pilots didn't see the other!).
J E Johnson mentiones an episode, where he was on a mission with his wing, and he saw some Dorniers flying along at some distance. He decided to wait for the first of his mates to call them out and then hand that guy the first shot. After what he thought were like two minutes, he reported the bogeys and thought it was only right that he would get them. The others would react with an icy silence after he mentioned that they were flying formation with the Dorniers for these like 2 minutes. It clearly shows that looking out is something you have to learn. And second is that those Dorniers were certainly not at the edge of where he could see them, they were much closer already. They were close enough for him to directly initiate an attack.
So, IMHO 777 can have their 10 km player bubble if they show then the appearing planes to everybody.
Felix qui potuit rerum cognocscere causas.