One way to estimate height is by a white-pine tree along the shore, below the object.
A mature white pine will be about 100' tall.
When I last saw A-10 "Warthogs" over Long Island, they may have been flying into a strong headwind. They appeared to hover in the air, but making sideways corrections of 20 or 30 feet in a split second.
Very impressive.
Also seen over
Center Harbor in 2008.
This is what they look like as one could see it from below:
