It can be very difficult to determine the thickness of the ice from the air. The sure thing, which I do when in doubt, is to put on an dry immersion suit, and walk the ice first. I take a battery drill, with a 12" long auger, and drill the ice, in a number of places where I propose to land. With totally clear ice, what you see is what you get. Other types of ice can be treacherous, even when "thick".
The ice pictured here is 10" thick, and that's the bottom of the lake 12 feet down you can see under the wheel!
