58
The ‘Don’t Sink’ pop-up terrain alert accompanies the
aural message for the NCR alert. The aural message
“Don’t Sink” or “TOO LOW, TERRAIN” is issued
also.
Section 3
TAWS Alerts
Negative Climb Rate After Takeoff Alert (NCR)
The purpose of the Negative Climb Rate 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 conditions 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 3-5 shows the NCR alerting parameters as defined by TSO-C151b.
Altitude Loss (feet)
Height Above Terrain (Feet)
0
0
20
40 60
80
100 120
140
200
400
600
800
1000
"DON'T SINK"
Figure 3-5: Negative Climb Rate (NCR) Graph
