Navigation vents
Incremental Velocity Indicator
Provides visual indications of incremental velocity for the
longitudinal(forward-aft), laterall(left-rlght), and vertical (up-down)
axes of the spacecraft. These indicated incremental velocities represent
the amount and direction of additional velocity or thrust necessary to
achieve correct orbit, and thus are added to the existing spacecraft
velocities by means of the maneuver thrusters.