How do you determine the correct bank angle for a rate one turn?

To determine the correct bank angle for a rate one turn, the guideline is to use a formula based on the true airspeed (TAS) or calibrated airspeed (KAS). The appropriate bank angle for a standard rate turn—defined as a turn that completes 360 degrees in two minutes, which translates to a turn rate of 3 degrees per second—is typically found to be approximately 15% of the aircraft's KAS.

This relationship arises from the physics of turning flight, where the required bank angle increases with speed in order to maintain a desired turn radius. At lower speeds, less bank is required, while higher speeds necessitate a steeper bank to generate the necessary centripetal force for a turn without increasing load factors excessively. Thus, using 15% of the KAS ensures that the aircraft can turn efficiently and safely while maintaining controlled flight parameters.

Other options suggest different percentages, which would not align with the conventional standards used in aviation to determine this specific bank angle for a rate one turn.