1. Bind more than one easily accessable keybind to Collective Raise (Beware of key conflicts on some keyboards)
2. Spawn any helicopter, and enter it, enable Auto Hover
3. Locate the vertical speed indicator (Or just listen to the engine/rotor load)
4. Push ONLY ONE of the keybinds, for example, Q. Observe your climb rate.
5. Push the second, additional, keybind, simultaneously. For example W, so, you're now pressing W + Q.
6. Observe that climb rate increases with the addition of another button press - You can let go, and press, the second key repeatedly to see, and hear, the effect.