GTN 750 and STEC 60-2

[markoebert]

We recently upgraded our Bonanza F33A with the Garmin GTN 750 and upgraded our STEC 60-2 with electric trim and added GPSS. I have done some initial test flights after working on the simulators and studying the manuals but am still unclear about some of the settings for specific approaches. Unfortunately, there is no manual for the combination. My biggest question is regarding settings for GPS approaches that provide vertical guidance (LPV). Once on an inbound course of a GPS approach that provides glide path data, what are the settings on the 750, the GPSS/HDG switch and the STEC to allow the AP to lock on to the glide path like it does for the glideslope of an ILS?

 

[ZeroPapaGolf]

We recently upgraded our Bonanza F33A with the Garmin GTN 750 and upgraded our STEC 60-2 with electric trim and added GPSS. I have done some initial test flights after working on the simulators and studying the manuals but am still unclear about some of the settings for specific approaches. Unfortunately, there is no manual for the combination. My biggest question is regarding settings for GPS approaches that provide vertical guidance (LPV). Once on an inbound course of a GPS approach that provides glide path data, what are the settings on the 750, the GPSS/HDG switch and the STEC to allow the AP to lock on to the glide path like it does for the glideslope of an ILS?

You want to select NAV mode, and it will automatically switch to APR mode. GPSS switch will have no function in this mode.

Sent via teletype

 

[gismo]

You want to select NAV mode, and it will automatically switch to APR mode. GPSS switch will have no function in this mode.

Sent via teletype

AFaIK, unless the STec is in approach mode (entered automatically or manually) it will NOT capture a glideslope. This is true whether the guidance source is an ILS or a RNAV LPV.

The typical sequence for a LPV approach (without vectors) would start with GPSS and switch to Nav or Approach mode at least a minute before intercepting the glideslope, then switching back to GPSS if you miss. That last step is easy to forget.

 

[ZeroPapaGolf]

AFaIK, unless the STec is in approach mode (entered automatically or manually) it will NOT capture a glideslope. This is true whether the guidance source is an ILS or a RNAV LPV.

The typical sequence for a LPV approach (without vectors) would start with GPSS and switch to Nav or Approach mode at least a minute before intercepting the glideslope, then switching back to GPSS if you miss. That last step is easy to forget.

Exactly. The only minor point to that I would have is that you can't select APR mode yourself...it automatically sequences to APR from NAV.

Sent via teletype

 

[gismo]

Exactly. The only minor point to that I would have is that you can't select APR mode yourself...it automatically sequences to APR from NAV.

Sent via teletype

IIRC the 60-2 switches goes into APR mode if you select a LOC frequency on the nav receiver or load a GPS approach with vertical guidance.

 

[poadeleted20]

What the autopilot can't do is capture the GS in the GPSS mode. You have to be in a mode in which the autopilot is getting its information from the CDI needles, not the GPS directly.

 

[taters]

GPS APPCH
Be nav-sourced to the GPS, APPCH mode is what allows GS mode to activate so long as you intercept the GS, appropriate lateral guidance is given also in APPCH mode.

ILS APPCH
Be nav-sourced to the loc freq. HDG and ALT mode is what you want during Vectors... arm APPCH mode once cleared and on a intercept HDG. MAKE SURE ALT mode shuts off and GS mode activates at GS intercept.