Aircraft Targeting Issue

[Greyfox]

One of us has always interpreted this as meaning that only enemy units that are spotted by a friendly leader may be attacked by aircraft, along the lines of the existing spotting rules for OBA bombardments. The other player, interprets this rules as meaning that it is the attacking aircraft that is doing the spotting, not a friendly leader on the map board. Hence a unit in CLEAR terrain may be attacked by aircraft without needing to be spotted by a friendly leader.

 
Neither of you are correct.  8.0 has your answer: "Spotting is seeing the enemy so you can shoot him, and is only performed by combat units (1.2), and sometimes leaders. 

Aircraft don't spot.  Leaders need to spot for bombardment fire and aircraft do not use bombardment fire.   The aircraft can only target spotted units thus the target must be spotted before the aircraft is placed, and "spotted" in this case is any unit with a spotted marker on it on ne within spotting range of a friendly unit not in limited terrain.   No leader is required.  You both are reading something in the rule that is not there.

The stricture in the rule is:
"However, they are prohibited from attacking unspotted enemy pieces located in limiting terrain "

So Only units unspotted, in limiting terrain, would be immune to aircraft....

If you're not in limiting terrain, you can be targeted.  
It's doesn't say they can only target spotted units---it says that in limiting terrain, it can only target spotted units....

So the lone tanks behind that forest in open ground, happily traversing the open ground, trying to sneak around that flank
where there are no enemy units to spot them--or on that road none of the enemy can see in the open---gets bombed....

Enemy units in CLEAR terrain CAN be bombed by aircraft--spotting is non-sequitur in this case....
(be in a field...it'd be different...)

       As an old OPFOR Leader at Hohenfels, Germany, and with years of experience moving or maneuvering mechanized or motorized columns on dirt roads or tank trails in both training and while deployed - I can attest that where ever you go dust is consistent.  Unless there is snow, or the ground is damp from rain, vehicles kick up dust.  Lots of vehicles kick up lots of dust high into the air - creating dust columns that you can see from a distance, even over hill tops and in the next valley.   Moving on dry dirt roads or tank trails is necessary, even in close proximity to the enemy, because it is the fastest way to move move troops.
     When you  close with the enemy, you deploy your force from column to line to attack or defend.  When that happens you typically deploy and attack across open fields (grass) - eliminating any dust columns.   That would also support your argument that pilots can see search for an find vehicles or concentrations of vehicles without being told to do so.

Mike