User's Manual

Chapter 4 – Principles of Operation
SKY899 Pilot’s Guide
4-5
Preliminary
Audio Inhibit, SKY899
This audio inhibit feature prevents the aural part of TAs,
“traffic traffic,” from being announced during takeoff and
landing in order to minimize pilot distraction. The correspond-
ing
TA symbols are still displayed.
The
SKY899 uses this audio inhibit feature in the following
situations:
1. Your aircraft has a radio altimeter and you’re below
400
ft AGL. (See figure 4-1.)
2. Your aircraft has no radio altimeter but its retractable
landing gear is down. (See figure
4-2.) (Audio is not
inhibited if you have fixed landing gear and no radio
altimeter.)
Audio Inhibit, GPWS, EGPWS, or TAWS
If your aircraft has a Ground Proximity Warning System
(
GPWS), Enhanced GPWS (EGPWS), or Terrain Awareness and
Warning System (TAWS) interfaced with the SKY899 and an
alarm from one of those systems occurs, the
SKY899 senses the
alarm and delays the aural “traffic, traffic” component of any
TAs issued until the alarm clears.
Audio Inhibit
Figure 4-3. TA Zones If Your Aircraft Has No Radio Altimeter
and a Fixed Landing Gear
0.2 nmi
+600 ft
–600 ft
T
h
i
s
a
r
e
a
or 2
0
s
e
c
o
n
d
s
*
0.55 nmi
+800 ft
–800 ft
T
h
i
s
a
r
e
a
or 30
s
e
c
o
n
d
s
*
*
**15 seconds for non-altitude reporting intruder aircraft
*20 seconds for non-altitude reporting intruder aircraft
Not to scale
Intruder aircraft
GL
TA zone
when your ground
speed is unavailable,
or when your ground
speed is available,
but is greater than or
equal to 120 knots
(sensitivity level B)
TA zone
when your ground speed
is available and is
less than 120 knots
(sensitivity level A)