Why Does The HSI Not Respond Like A VOR When OBS Mode Is Active?

Unlike a VOR, the CDI scale used on GPS equipment is based on the crosstrack distance to the desired course, not on the angular relationship to the active waypoint. Therefore, the CDI deflection on the GPS is constant regardless of the distance to the active waypoint and does not become less sensitive when further away from the active waypoint.

190-03123-01 Rev B
July 2026