Terrain Banding

The MH60-T community often harnesses terrain banding in low visibility conditions, as it provides some excellent situational awareness and is a critical safety tool. However, because terrain banding is not a precision navigation tool, there are four things to consider: 

• Terrain banding is based on MSL. It is only as accurate as your altimeter setting.  To demonstrate this, fly at a consistent altitude while adjusting the helicopter’s altimeter setting and watch the terrain banding change (e.g., select the altimeter setting field in the CDU and twist the large ring on the multifunction knob to change the altimeter 0.1 each click to see the altimeter’s impact on terrain banding).

• Terrain banding is based on “rocks and dirt,” not obstacles (e.g., trees and towers) and there are some documented errors in the database the tool references (DTED).  

• The terrain banding display will not update when the moving map is in PAN. To demonstrate this, start at a high altitude over hilly or mountainous terrain, put the map in PAN, then descend. When the pilot takes the map out of PAN, terrain banding will “bloom” and he or she will see how a crew who is unaware of this “gotcha” could unknowingly get themselves in a dangerous situation provided the right circumstances. 

• Moving maps lack precision. To demonstrate this, pick several fixed objects throughout a flight on the moving map sectional (e.g., the shoreline of a lake), zoom in on the map, and fly directly over them. Note that the depiction of the helicopter on the moving map will be displaced varying amounts from the objects.

Using GMAP2 with a 3 degree up tilt is a technique to correlate terrain banding with a RADAR image.  The image not only pairs well with terrain banding, but can be used as another source of situational awareness with respect to upcoming terrain in forward flight.