Document Type


Publication Date





Twenty-three helicopter pilots flew a simulated Bell 206 in Helicopter Emergency Medical Service (HEMS) scenarios with obstructions present. In Study 1, the head-mounted display (HMD) showed highway-in-the-sky guidance but not obstructions. Study 2 added obstructions (broadcast towers, power lines) in the HMD. Pilots detected and avoided HMD-depicted obstructions earlier than those only shown out the window. Wire strikes were frequent without HMD depictions of obstructions but were greatly reduced when these objects were shown in the HMD. They were completely eliminated when a red warning fence was overlaid on the power-line graphic at the point it transected the flight path. Pilots indicated that the power-line representation was slightly ambiguous in its meaning, but the red warning fence intent was clear. Pilots preferred power lines without the ground-plane representation and realistic complex green imagery for guy wires, and red/white striped towers with beacons and digital tower elevations.