I would assume the spotter in the plane (not the pilot) might have binoculars, and be able to spot infantry from a hundred meters or more.
Weather or not they could reliably tell friend from foe on the other hand depends on how good those binocs are.
Which presents two problems.
If the spotter has binoculars, flying at an altitude between 100-200m directly above your target area makes it pretty much impossible to see anything due to the movement of the aircraft. Remember, it's still flying with roughly 100mph (roughly 50m/s) and the pilot would have to constantly adjust the plane to keep it somewhat in the area.
The only way to have a steady enough flight to spot something with binoculars is when flying a couple of hundred meters away and spotting towards the horizon. Let's say 300m above ground level and spotting 500m towards the horizon. This would give you a rather stable point of view and would enable you to accurately use your binoculars. Would you be able to ID individual solders? Probably not. This would also get the aircraft out of any effective fire from infantry weapons (remember that's roughly 700m distance to the aircraft which is still moving at a speed of 100mph).
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