Garmin G1000 NXi Pilot’s Guide for the Cessna NAV III
190-02177-02 Rev. A
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
272
HAZARD AVOIDANCE
The pilot enables/disables the NEXRAD animation feature for navigation maps from the ‘Map - Navigation
Map’ Page.
Displaying Time-Lapse NEXRAD Animation on navigation maps:
1)
Select the ‘Map - Navigation Map’ Page.
2)
Press the
MENU
Key.
3)
With ‘Map Settings’ highlighted, press the
ENT
Key.
4)
Turn the
FMS
Knob to select the ‘Weather’ Group and press the
ENT
Key.
5)
Turn the large
FMS
Knob to highlight the NEXRAD Animation On/Off field.
6)
Turn the small
FMS
Knob to highlight ‘On’ or ‘Off’ and press the
ENT
Key.
7)
To remove the menu, push the
FMS
Knob or the
CLR
Key.
r
eFlectivity
Reflectivity is the amount of transmitted power returned to the radar receiver. Colors on the NEXRAD
display are directly correlative to the level of detected reflectivity. Reflectivity as it relates to hazardous
weather can be very complex.
The role of radar is essentially to detect moisture in the atmosphere. Simply put, certain types of weather
reflect radar better than others. The intensity of a radar reflection is not necessarily an indication of the
weather hazard level. For instance, wet hail returns a strong radar reflection, while dry hail does not. Both
wet and dry hail can be extremely hazardous.
The different NEXRAD echo intensities are measured in decibels (dB) relative to reflectivity (Z). NEXRAD
measures the radar reflectivity ratio, or the energy reflected
back to
the radar receiver (designated by the
letter Z). The value of Z increases as the returned signal strength increases.
No Radar Coverage
Figure 6-11 NEXRAD Weather Product Legend
neXraD l
iMitations
NEXRAD radar images may have certain limitations:
Undetermined precipitation types may be displayed as mixed.
An individual NEXRAD site cannot depict high altitude storms at close ranges. It has no information
about storms directly over the site.
Precipitation may be occurring below the lowest antenna tilt angle (0.5
º
), and therefore the radar beam
overshoots the precipitation. For example, at a distance of 124 miles from the radar site, the radar beam
is approximately 18,000 feet above the radar site. The radar cannot detect any precipitation occurring
below the beam at this distance and altitude.