HORIZONTAL SITUATION INDICATOR (HSI)
The Horizontal Situation Indicator (HSI) consists of elements that give
essential information to pilot using graphics, text and symbols.
The Horizontal Situation Indicator has three formats that can be selected by
the Display Controller (DC):
• FULL COMPASS FORMAT
It presents a 360° compass card overlaid with navigation data given by
the bearing pointers and course deviation indicator (CDI)
• ARC FORMAT
It shows an expanded quadrat of the compass that is 45° either side of
the current heading overlaid with navigation data given by bearing
pointers and the CDI. It is possible to also overlay the FMS flight plan
(MAP pushbutton on DC) and, if associated equipment is installed, also
the Weather Radar or the EGPWS images (WX/TERR pushbutton on
DC).
• HOVER FORMAT
It presents the aircraft longitudinal and lateral velocities with the FMS
map on a 360° display. The hover display format gives the pilot a
display of the aircraft longitudinal (along the heading) and lateral
(across the heading) velocities and a desired velocity reference bug for
the FD (see chapter 22-00).
The hover format permits overlay of the FMS map data to give
situational awareness during the hover.
The hover format can be selected by toggling the HSI button on the
DC; it is also automatically selected when either the Hover (HOV),
Transition Down (TD) or Mark On Target (MOT) FD modes are
selected.