BACK COURSE (BC) MODE
The BC mode allows the aircraft to capture and track the inbound back
course of the localizer for approach to a runway by providing the lateral
guidance in the roll axis.
After tuning, the course pointer on the PFD must be set to the runway
inbound course, with the heading bug set to the necessary intersection
heading. When the BC button is pressed on the GC, HDG mode is
automatically engaged and BC armed. The BC mode operates in the same
way as the LOC mode with the deviation and course signals that are
opposite to make a BC approach to the localizer.
GA — GO AROUND MODE
The Go-Around mode (GA) provides aircraft control for an automatic ascent
profile. The function is intended primarily for use during the approach phase
of flight to initiate a missed approach.
GA mode is engaged by pressing he GA pushbutton on either collective; any
other mode is then disengaged.
Upon engagement the GA mode commands collective for a 1,000 ft/min
climb, roll for wings-level and pitch for an airspeed of 80 KIAS or the current
airspeed, whichever is higher.
OS — OVER STATION MODE
When overflying a VOR station, with VOR or VAPP mode engaged, the VOR
equipment detects the aircraft being within the zone of ambiguity.
The VOR deviation signal is removed from the command until the VOR
signal has stabilized after passing over station, when the OS mode
disengages returning to VOR or VAPP mode automatically.
While over the station, course change may be made by selecting a new
course via the COURSE knob on the RIC: aircraft is steered heading
towards the selected course until OS mode is replaced by VOR or VAPP.
ALVL — AUTOLEVEL MODE
If the APP (LOC/GS or VGP) mode is continued, to below landing minimum,
this safety feature is automatically activated at 150 ft AGL and an asymptotic
flare to a radar height of 50 ft AGL will be initiated.
The green GS or VGP caption on the PFD will be replaced by ALVL.
CAUTION
IN VGP MODE THE ALVL WILL NOT ACTIVATE IF THE MISSED
APPROACH POINT (MAP) HEIGHT ALONG THE VGP IS HIGHER
THAN 150 FT AGL. FOR THIS CASE THE VGP MODE WILL
DISENGAGE AT THE MAP (PRECEDED BY A VERTICAL TRACK
ALERT (VTA) CAPTION DISPLAYED IN THE UPPER RH QUATER
OF THE ADI) AND A CHIME IS GENERATED.