Funny, this happens to be a briefing item for my next flightJust started low levels, I can almost see the end of the tunnel. . .
Hah, nice timing! Like was said above spyguy, TERF = terrain flight. 3 types of TERF: low-level, contour and nap-of-the-earth (NOE).
Low-level is mostly straight-tline, but below 500 AGL.
Contour is following the terrain from one point to another, but still fairly direct at approximately <=200ft taking advantage of the boundary layer, masking, orographic winds etc etc.
NOE is flying as LOW as you possibly can, following the terrain VERY closely and VERY slow. Think: above translational lift up a small hill and popping out from behind a fucking tree.
You get to do only LL in the HTs, TERF in the RAG and NOE will be sometime after that... if at all.
Now read up and go get 5s on that brief!