Bearing to Bogey will not be used.
Range R, Altitude A (relative to the P-61), Course C (away from P-61, side, toward P-61), Speed S.
P-61 must decide Altitude and speed. When GCI vectors P-61 to Bogey, RCAS and P-61 S will give you modifiers.
You are flying in the dark. You cannot see anything which is not within visual range. GCI will guide you toward the Bogey, set you on an intercept course.
When you are close enogh your radar operator can hopefully get the Bogey on his screens and take over from GCI. The goal is to visually identify the Bogey and if it is an enemy, shoot it down.