Suppose I stand at p = (latitude,longitude) on earth. I want to manually check for any airplane flying overhead in my neighborhood with naked eye and without any equipment.

I scan air-traffic radars for every plane in the vicinity of my location meaning probe_region: latitude ± δ , longitude ± δ (we assume a region of square geometry for simplicity)

1- How far away can a man hear the jet engine of airplanes? Meaning what should be the radius of probe (or in this square case ~δ)

2- How far away can a man see the body of an air plane in clear sky with naked eye?

I'm looking for answers in kilometers or miles. (converting from radius in kilometers to (lat/lon) interest_box is another problem, like 1 deg in latitude is ~110 km)

In the diagram below, the plane inside the blue bound can be heard from p but the plane just outside of it can't be heard (I assume we can hear engines sooner than we can observe the whole plane)