And that tells you EXACTLY what the "Eye" represents, you didn't have to make strange connections. Go to the top of the mountain, see the UFO, obviously they EYE symbols are UFO's.
They left a clue, you followed it and foun out what it was, you didnt have to "Interperet" or do any guess work, they showed you what it means, very deliberately.
ALSO, they EYE looks like a UFO, they didn't draw a Walrus on top of the mountain to represent a UFO, they drew a UFO on top of the mountain, some see an EYE, i immediately saw a UFO before thinking it was an EYE.
I disagree that it's that obvious. Even if somehow you assume that the jetpack was supposed to represent flying above the military base;
You wouldn't because you had that prior knowledge. It is natural when disavowing prior knowledge to assume that the opposite stance would be taken, but that isn't the case.
Without knowledge of what a jetpack is, you cannot understand this sign. However, recognising the shape entails recognising the object, an experimental form of flight, where footage of such tests take place in airfields such as at the Fort. Also, recent media have shown personal flight devices as having militaristic trials, eg Spider-Man.
I'd be happy to be disproven on this but it ties in too well to not be the obvious and therefore accepted truth.
Why not draw a stickman with a gun? It'd be vague enough in a game about shooting, but would be enough to make sense when linked to the base.
Why pick something that represents one of the coolest and most interesting unlockable items from the previous iteration of San Andreas state?
Assuming prior knowledge it disappoints. Without prior knowledge it requires a logical leap.
When people think of jetpacks, they don't think of recent events or experiments in the army. They think of James Bond and Spy movies.
They think of things like the Jetsons with futuristic travel, etc etc.
Tons of things would come to my mind as the symbols purpose (especially thanks to Grand Theft Auto: San Andreas) before linking it directly to the military and assuming "Well! That's the puzzle done.".
It just doesn't add up to me.
They added fantastical things that weren't inGTA SA to GTA V because they were rumoured to be in it. Why not then NOT include a fantastical thing that was in SA? For a laugh! Its a pretty funny dick move. Plus it further shows self referencialism to SA