I guess I should have quoted his entire sentence, "When you pull up."

I know a graveyard spiral doesn't have a constant bank. My point is, back pressure, applied between 1 and 89 degrees of bank, will never increase horizontal at the expense of vertical or vice versa. It will increase both.

Vertical component = sin [bank angle] * total lift
Horizontal component = cos [bank angle] * total lift

So 3 things: speed, AOA, and bank angle change the components of lift. One doesn't change at the expense of another. (Can one of you aero engineers confirm those formulas? I don't have a book in front of me to check them.)



My suspicion with the PHAK sentence quoted, but without further review I am unsure, is that the resultant decrease is from a decrease in speed due to increased induced drag. Meaning, the initial experience will be a small decrease in descent, from the increase in lift.

However, when speed falls low enough total lift will decrease below the point where the back pressure was introduced. At that point, the turn will still be tighter but a descent would result.

IMO this coupled with the continued increase in bank angle would account for the continued decrease in vertical lift component. Absolutely nothing to do with the increase in horizontal at the expense of vertical.