This paper will focus on the practical incorporation of "tunnel-in-the-sky" and synthetic vision concepts from a flight simulation software perspective. Piloted, rotorcraft flight simulation analysis of these concepts has been an ongoing activity in the Boeing Flight Simulation Laboratory in Philadelphia. The theoretical basis and advantages in augmenting pilot situational awareness was well presented by Robert R. Wilkins. 1 In this paper, the technical issues involving design architecture, visual perception and verification of these concepts will be addressed. Some of these issues include architecture optimization for future enhancements, tunnel correlation and conformality with out-the-window terrain, validation of pilot visual cues and integration of tunnel and synthetic vision concepts. Future work and directions will also be discussed, for both tunnel symbology-based guidance and synthetic vision situational awareness, in the context of practical realization in a rotorcraft flight simulation environment.acceleration of gravity T H = tunnel height -ft H B = barometric altitude -ft T HDG = tunnel heading -deg H P = pressure altitude -ft T T = tunnel turn radius -deg F F = function factor -normalized T W = tunnel width -ft F pv Δθ = flight path vector delta pitch -deg T Y = tunnel yaw -deg F pv Δψ = flight path vector delta yaw -deg V A = true airspeed -kn K PHI = gain on bank angle V C = calibrated airspeed -kn K TAE = gain on track angle V G = groundspeed -kn K XTD = gain on cross track deviation V R = reference speed -kn N G = north cig coordinate -ft V RC = vertical velocity -ft/s N Xwp = next waypoint index -unitless X L = aircraft longitude -€ ˙ P O = push-over rate -deg (deg/min/s) S L = tunnel segment length -feet XTD = aircraft cross track S S = tunnel segment spacing -feet deviation -perpindicular TAE = aircraft track angle error -difference distance from aircraft between tunnel course and aircraft center of gravity to tunnel ground track angle -deg ground track -ft T A = tunnel altitude -ft Y L = aircraft latitude -(deg/min/s) € ˙ φ = aircraft roll rate -deg/s Z B = tunnel flight profile height -ft θ = pitch angle -deg BRYCHCY ET AL. 240 ΔP Y = power cue vertical offset -in. (display) ϑ (5) = fifth order polynomial ΔT = simulation execution time -s quantity -unitless ΔT C = command-frame time -s ψ = aircraft heading -deg ΔT F = lead-frame time -s € ˙ ψ = aircraft yaw rate deg/s ΔT L = look-ahead time -s ψ M = aircraft magnetic heading -Δθ Y = pitch cue vertical offset -in. (display) deg φ = aircraft bank angle -deg ψ T = aircraft true heading -deg