From the Errata
Pg 221
Airborne Units: Against other airborne units, use the Visible Range Table as usual. However, against ground units, an airborne unit is only able to visually detect units along its flight path and must be at or below Altitude 8.
What scale does this correspond to? Low Altitude map scale where every hex traveled over is an entire ground map? Aerospace unit on the ground map scale?
I would guess Low altitude map scale is the intent. Allowing an aerospace unit to only see a 1 hex wide strip of a map would kinda negate the usefulness of a Boomerang spotter plane. Especially since it would have no Idea who is shooting at it as every ground unit on the map can see it.
Secondary question.
Still on Page 221
"If at Altitude 1 (NOE), the unit is considered grounded."
Would this mean a fighter at Altitude 1, would be able to see other ground units just as well as a mech in clear conditions?