Terrain flying both day and night is now an Army Aviation tactical requirement. The present investigation compared terrain flight for Low Level (LL) and Nap-of-the-Earth (NOE) profiles for 1) day flight with the unaided eye, 2) night flight with the unaided eye, and 3) night flight using Night Vision Goggles. Data was acquired through use of the Helicopter In-flight Monitoring System (HIMS). The total set of in-flight measures for LL and NOE were analyzed separately with further analysis on the subsets of pilot control variables, and aircraft status variables. Multiple discriminant analysis techniques were used to determine which measures best discriminated between visual conditions.