Garmin G1000 King Air C90GT - Manual (Page 344)

Garmin G1000 Pilot’s Guide for the Hawker Beechcraft C90A/GT 190-00663-01 Rev. A 330
HAZARD AVOIDANCE
SY
STEM
O
VER
VIEW
FLIGHT
INSTRUMENTS
EIS
AUDIO P
ANEL
& CNS
FLIGHT
MANA
GEMENT
HAZARD
AV
OID
ANCE
AFCS
ADDITIONAL FEA
TURES
APPENDICES
INDEX
h
ail
Hail results from updrafts carrying water high enough to freeze. Therefore, the higher the top of a
thunderstorm, the greater the probability that it contains hail. Vertically scanning the target return can
give the radar top of a thunderstorm that contains hail. Radar top is the top of a storm cell as detected by
radar. It is not the actual top, or true top of the storm. The actual top of a storm cell is seen with the eyes
in clear air and may be much higher than the radar top. The actual top does not indicate the top of the
hazardous area.
Hail can fall below the minimum reflectivity threshold for radar detection. It can have a film of water on
its surface, making its reflective characteristics similar to a very large water droplet. Because of this film of
water, and because hail stones usually are larger than water droplets, thunderstorms with large amounts
of wet hail return stronger signals than those with rain. Some hail shafts are extremely narrow (100 yards
or less) and make poor radar targets. In the upper regions of a cell where ice particles are dry (no liquid
coating), target returns are less intense.
Hail shafts are associated with the same radar target return characteristics as tornados. U-shaped cloud
edges three to seven miles across can also indicate hail. These target returns appear quite suddenly along
any edge of the cell outline. They also change in intensity and shape in a matter of seconds, making vigilant
monitoring essential.
OPERATION IN WEATHER MODE
WARNING: Begin transmitting only when it is safe to do so. When transmitting while the aircraft is on the
ground, no personnel or objects should be within 11 feet of the antenna.
CAUTION: In Standby mode, the antenna is parked at the center line. It is always a good idea to put the
radar in Standby mode before taxiing the aircraft to prevent the antenna from bouncing on the bottom stop
and possibly causing damage to the radar assembly.
When the weather radar system is in the Weather or Ground Map mode, the system automatically switches
to Standby mode on landing.
In Reversionary mode, the weather radar system automatically switches to Standby mode. The system
remains in Standby mode until both displays are restored. In Reversionary mode, the weather radar system
cannot be controlled.