LNAV to ILS

veezeveeze
in Operational questions

I think I'm doing everything I am supposed to: LNAV on FMS flightplan, runway and ILS approach selected, autotuned, armed. I level off at the initial altitude prior to reaching the IAF and activate the approach. The EFIS changes to LNAV APCH, and the vertical deviation bar appears. The aircraft then stays in level flight. What am I not doing right?

Comments

  • rondon9898rondon9898

    To capture the ILS you need the ILS tuned in the ARCDU, preferrably on both NAV boxes and your HSI - both sides preferrably - in nav/cyan (rather than FMS/magenta), and press the APPR button on the FGCP.

  • veezeveeze

    I figured it out on about the 7th try...

    I flew to the IAF level at the initial altitude, and at the IAF the approach auto-activated. I waited for the VERTICAL ALERT and then set the altitude selector to field elevation and hit VNAV. It worked just fine.

    Thanks for your comment rondon, but it can all be done in FMS/magenta. Reading some of the other threads on RNAV approaches was helpful.

    I'll keep trying in some more complex situations and report back.

  • rondon9898rondon9898

    Yes, but you are flying an RNAV approach or an RNAV overlay approach there, not an ILS. To fly a bona fide ILS approach you need to be using the raw data from the ILS in GS and LOC mode.

  • veezeveeze

    I don't think so...

    From paragraph 16.9.7. of Majestic's tutorial:

    "Approach types:

    The FMS will fly the following approach types as RNAV overlay approaches:  RNAV approach  NDB approach  NDB-DME approach  VOR approach  VOR-DME approach

    The FMS will use the navaid data directly for the following approaches  LOC approach: all types  ILS approach: all types."

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