AIRPLANE
OPERATIONS
MANUAL
NAVIGATION AND
COMMUNICATION
REVISION 38
2-18-45
Page
9
Code
01
AOM-145/1114
RAIN ECHO ATTENUATION COMPENSATION TECHNIQUE
FUNCTION (REACT or RCT)
The REACT is a sub mode of the weather detection mode and when
selected activates three separate but related functions:
−Attenuation Compensation - Storms with high rainfall rates can
attenuate the radar energy making it impossible to see a second cell
hidden behind the first cell.
In the REACT mode, the radar incorporates a function that
automatically adjusts receiver gain by an amount equal to the
amount of attenuation, i.e., the greater the amount of attenuation, the
higher the receiver gain and thus, the more sensitive the receiver.
−Cyan REACT Field - Since there is a maximum limit to receiver gain,
strong targets (high attenuation levels) cause the receiver to reach its
maximum gain value and weather targets can no longer be
calibrated. The point where red level weather target calibration is no
longer possible is highlighted by changing the background field from
black to cyan.
Cyan areas should be avoided. Any target detected inside a cyan
area should be considered very dangerous. All targets in the cyan
field are displayed as a magenta-colored 4
th
level precipitation.
−Shadowing - This is an operating technique similar to the Cyan
REACT Field. To use the shadowing technique, tilt the antenna down
until the ground is being painted just in front of the storm cell(s). An
area characterized by no ground returns behind the storm cell has
the appearance of a shadow. The cell that produces radar shadowing
is a very strong and dangerous cell and should be avoided by 20 NM.
FLIGHT PLAN MODE (FP)
When the Flight Plan Mode is selected a singular display of navigation
data and a FLTPLAN label are presented on the PFDs’ and MFDs’
radar mode field. The radar is put in standby and there is no radar
data displayed in this mode.
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