skypimp:

I need to know if "airspeed" means Indicated, or True.

As long as we are not talking compressible theory (ie, light airplanes and low Mach numbers), then for a given IAS, the AOA will essentially stay constant.

For constant True Airspeed, as you climb, the Indicated would go down...and you would need more AOA for the same amount of lift.

Even for what I fly (T-38), at altitudes up to the low 30s, and speeds usually up to 0.85-0.90, there is no discernable difference in AOA if the Indicated speed stays the same, regardless of altitude.

The noticable effect is from aircraft weight. Heavy with fuel at the beginning of the flight, more AOA; at the end, less.