Garmin GNS 530 - Manual (Page 213)

GNS 530(A) Pilot’s Guide and Reference 190-00181-00 Rev. H 13-9
SECTION 13
TAWS
Negative Climb Rate After Takeoff Alert (NCR)
The purpose of the Negative Climb Rate (NCR) After Takeoff alert (also referred to as “Altitude Loss After Takeoff”) is
to provide suitable alerts to the pilot when the system determines that the aircraft is losing altitude (closing upon terrain)
after takeoff. The aural message “Don’t Sink” is given for NCR alerts, accompanied by an annunciation and a pop-up
terrain alert on the display. NCR alerting is only active when departing from an airport and when the following condi-
tions are met:
• The height above the terrain is less than 700 feet.
• The distance from the departure airport is 2 nm or less.
• The heading change from the heading at the time of departure is less than 110 degrees.
Figure 13-9 shows two figures which illustrate the NCR alerting parameters as defined by TSO-C151b. The NCR alert
is issued when the altitude loss and height are within the range in the first figure, or when the sink rate (negative vertical
speed) and height are within the range in the second figure.
1000
800
600
400
200
Height Above Terrain (Feet
)
Altitude Loss (Feet)
0 20 40 60 80 100 120 140
“DON’T SINK” “DON’T SINK”
1000
900
800
700
600
500
400
300
200
100
Height Above Terrain (Feet
)
Sink Rate (Feet Per Minute)
0
“DON’T SINK” “DON’T SINK”
500 1000 1500 2500 3500 2000 3000 4000
Figure 13-9 Negative Climb Rate (NCR) Alert Criteria