I know the difference between the two approaches, and I saw the annunciator illuminate to say "LNAV." Yet I still was executing the approach as if it had a glidepath and no step-down fix
, even though the glideslope needle was flagged.
Without the step-down fix
, you can't descend any lower than the step-down fix
altitude on the approach.
In response, the CANPA procedures were developed, encouraging operators to establish a stabilized, constant-rate descent after crossing the FAF or a step-down fix
, with the idea of arriving at or near the MDA and sighting the runway environment at roughly the same time.
We spoke with our contact at Bendix/King to get to the bottom of the missing step-down fix
and to learn about other limitations the KLN-series of navigators might have.
There may be one or more step-down fixes
between the FAF and the missed approach point (MAP).
I would not teach or approve disregarding a step-down fix
altitude on an instrument approach in "good VFR" at night, period.
Holston states, "An increasing number of LNAV approaches have an advisory glideslope available." Pilots must only use "advisory" vertical guidance to help meet the step-down fix
and MDA altitudes, but--foot stomper important because this will be on the test later--pilots must use the altimeter to comply with any altitude restrictions.
Using distances past a known fix would work, but that's too much mental math for our aging brains when it comes to something as important as a step-down fix
. Using the MAP for the opposite runway would not be a good idea, as the localizer antenna could be well past the end of the runway and the MAP isn't always at the runway threshold.
By the way, JEBIX, the last step-down fix
for the localizer-only version of this approach, is not contained in the GX-60 database.
Coming from the north, you'll have the extra step of using R-320 for a step-down fix
, but that's still better than twisting every 10 degrees.
Shown (previous page) is Orlando (KMCO) RNAV (GPS) RWY 17L with several at-or-above step-down fixes
The essential information I needed to know on the final approach course inbound--the altitudes and step-down fixes
, as well as minimum descent altitude; the distances between the fixes and what determines the missed approach point (MAP); and the heading, altitude and hold entry should I need to fly the missed approach--were already sketched out on a Post-It[R] during my preflight planning and stuck to the paper chart.