Garmin GNS 530 Pilot's Manual And Reference page 193

following to occur when using the vertical navigation
feature:
angle also locks to prevent changes in speed from
altering the profile.
Figure 11-5 VNAV Profile Message
the desired vertical speed to maintain the proper
190-00181-00 Rev. G
GNS 530(A) Pilot's Guide and Reference
VERTICAL NAVIGATION
blanked out, at this point.
Figure 11-6 Target Altitude Message
SECTION 11
11-3