A320 radial equivalent
Guys,
A320 FCOM - Special Ops - RNP 10
"If manual entry of a required accuracy is desired, the flight crew must manually enter
For RNP-10, enter 10 nm or use the radial equivalent to 10 nm XTK accuracy that is 12.2 nm."
What does the last part mean? "radial equivalent to 10 nm XTK accuracy" is something I've never heard before..