Piper ARCHER III Pilot Operating Handbook page 221

PA-28-181, ARCHER III
NORMAL PROCEDURES
5. GPS approach (GPS APR ARM/ACTV) switch/annunciator -
(KLN 89B only) used to (a) manually select or deselect approach
ARM (or deselect approach ACTV) and (b) annunciate the stage
of approach operation either armed (ARM) or activated (ACTV).
Sequential button pushes if in ACTV would first result in
approach ARM and then approach arm canceled. Subsequent
button pushes will cycle between the armed state (if an approach
is in the flight plan) and approach arm canceled. Approach
ACTV cannot be selected manually. GPS APR and ARM are
white. ACTV is green.
6. RMI NAV presentation switch - May be used to select data for
presentation on the RMI; either NAV 1 data from the number one
navigation receiver, NAV 2 data from the number two navigation
receiver or GPS data from the KLN 89 (B) GPS.
C. PILOTS DISPLAY
Left/right steering information is presented on the pilot's HSI as a
function of the NAV/GPS switch position.
D. AUTOPILOT COUPLED OPERATION
The KLN 89 (B) may be coupled to the autopilot by first selecting
GPS on the NAV/GPS switch. Manual selection of the desired track on
the pilot's HSI course pointer is required to provide course datum to
the autopilot. (Frequent manual course pointer changes may be
necessary, such as in the case of flying a DME arc.) The autopilot
approach mode (APR) should be used when conducting a coupled
GPS approach.
Select HDG mode for DME arc intercepts. NAV
or APR coupled DME arc intercepts can result in
excessive overshoots (aggravated by high ground
speeds and/or intercepts from inside the arc).
ISSUED: JULY 12, 1995
REVISED: APRIL 3, 1997
NOTE
SECTION 9
SUPPLEMENT 4
REPORT: VB-1611
9-21