1. S-TEC 55X with Altitude Selector/Alerter (ASA)
Two axis, rate-based autopilot (from TC).
Pitch modes: ALT, VS, GS
Roll modes: HDG, NAV, GPSS, APR, REV APR

2. Roll Modes HDG: press HDG, aircraft flies hdg bug.
NAV: press/hold HDG, then press NAV, HDG and NAV are lit. Aircraft will fly hdg bug until intercept, HDG extinguishes and a/c flies CDI. (ensure CDI: VLOC)
GPS steering: press/hold HDG, then press NAV twice, HDG, NAV, GPSS illuminate. Aircraft will fly hdg bug until intercept. HDG extinguishes, a/c flies GPS flight plan. (ensure CDI: GPS)
Alternately, the pilot can allow autopilot intercept by pushing NAV without HDG. Full scale CDI will establish 45° intercept, progressively shallowing as intercept.
APR: for increased sensitivity during approach. Also increases sensitivity for enroute VOR, GPS tracking.

3. Pitch Modes
ALT: a roll mode must first be selected. Press ALT. ALT illuminates and aircraft holds current altitude. Altitude corrections can be made by rotating VS knob (20’/click, max.360’).
VS: Press VS, vs and current vs are displayed. Aircraft holds current vert. speed. Selectable in 100’/min increments (±1600 fpm max.).
GS: GS will arm when: NAV/APR/ALT selected; nav rcvr tuned to ILS freq.; glideslope not flagged; aircraft below glideslope ≥60% and w/in 50% LOC deflection. When GS is intercepted, alt will extinguish. GS mode can be forced by pressing ALT on 55X (e.g. if not below by 60% or above glideslope).
Press APR to disarm or rearm GS. Ensure CDI: VLOC.

4. ASA altitude selector/alerter
Provides altitude preselect, vertical speed select, altitude and DH audio alert, and baro-corrected altitude display.
Pilot can deselect ASA and revert to normal 55X
operation by pressing MAN.

5. ASA altitude selector/alerter
ASA has two modes:
Data entry – used to enter altimeter, desired altitude, and DH. Press DTA - ENT illuminates. ASA cannot communicate with 55X while in data entry mode. On pwr. up, ASA is in DTA mode waiting for altimeter setting. Use knob to enter altimeter, then press DTA to exit.
Operate – ENT will be extinguished. ASA provides vertical command info to 55X.
Press DTA to enter data entry mode – enter data (baro, alt, DH) – press DTA again to accept data and exit data entry mode.
VS can be set directly in the operate mode by pushing VS and turning knob (±1600 fpm).

6. ASA and 55X operation
ALT and VS modes are coupled to the ASA. ALT and VS outputs to 55X by pressing and holding VS then press ALT (on the 55X).
Before takeoff: enter cruise alt. and desired climb rate. After takeoff, above 400’ and in cruise climb: press and hold VS then press ALT (on 55X) to engage VS mode and arm altitude to capture and hold selected altitude.
To change altitude: press DTA – enter new altitude – press DTA – enter desired VS – press/hold VS then ALT (on 55X). Aircraft will climb or descend at selected rate and capture new altitude.

7. Gary Kauffman CFI, MEI, ATP
ASA Altitude Alerter
ALR: selected will provide alarms at 1000’ and 300’ from selected altitude.
DH: press DTA then DH to enter decision height/MDA, then DTA again to accept entry. As aircraft approaches w/in 50’ of selected altitude an alert will sound and DH will flash. DH will alert again when below by 50’. Pressing DH will disable DH function.
Gary Kauffman CFI, MEI, ATP