Section 8 Terrain Awareness Warning System
1
st
Ed Nov 2018
IDU-450 EFIS Software Version 8.0H (Rotorcraft)
8-1
Section 8 Terrain Awareness Warning
System
Enhanced HTAWS and HTAWS
8.1.
Enhanced HTAWS and HTAWS (Terrain Awareness Warning
System) Functions
The IDU provides TSO-C194 HTAWS functionality. Depending on aircraft
configuration and external sensors/switches, the system is configurable as
an Enhanced HTAWS or HTAWS. Functions provided by HTAWS are:
1)
Terrain Display
: Terrain and obstacles on PFD and ND.
2)
Forward Looking Terrain Awareness
(
FLTA
): Alerts to hazardous
terrain or obstructions in front of the aircraft.
3)
Excessive Rate of Descent
(
GPWS Mode 1
): Alerts when
hazardously high rate of descent above terrain (i.e., descending into
terrain).
4)
Excessive Closure Rate to Terrain
(
GPWS Mode 2
): Alerts when
hazardously high rate of change above terrain (i.e., flying level over
rising terrain).
5)
Sink Rate after Takeoff or Missed Approach
(
GPWS Mode 3
): Alerts
when loss of altitude is detected immediately after takeoff or initiation
of a missed approach.
6)
Flight into Terrain when not in Landing Configuration
(
GPWS
Mode 4
): Alerts when descending into terrain without properly
configuring the aircraft for landing.
7)
Excessive Downward Deviation from an ILS Glideslope
(
GPWS
Mode 5
): Alerts when deviating below glideslope on the final approach
segment of an ILS approach.
Table 8-1: TAWS Functions Provided by the EFIS
Aircraft Type
TAWS
Class
Terrain
Display
FLTA
GPWS Mode
1 2 3 4 5
Rotorcraft RG
Enhanced
Rotorcraft FG
Enhanced
Rotorcraft Normal
Notes: RG = Retractable Gear; FG = Fixed Gear
