Key findings from a 2009 OSD study of all DOD Rotary Wing, Class A/B mishaps concluded that 80% of Rotary Wing Losses and 70% of fatalities are not due to hostile fire, but four factors (Brownout, Controlled Flight into Terrain (CFIT), Object/Wire Strikes, and Engine Failures). An investigation conducted by the National Transportation Safety Board (NTSB) of Commercial Helicopter Air Ambulance accidents from 2003-2010 reported 99 accidents, resulting in 99 lives lost due to similar conditions.

Brownout and whiteout are conditions that occur during landing, hovering, and take-off where the thrust from the main rotor blades of the helicopter blows up so much dust (Brownout) or snow (Whiteout) that the aircrew is unable to see outside of the aircraft. As brownout or whiteout occurs, the aircrew loses situational awareness of the aircraft relative to the earth and other aircraft. The aircrew subsequently loses control of the aircraft resulting in a crash. A broader definition is Degraded Visual Environment, which included natural obscurants like fog, rain, snow, and man-made obscurants like smoke. All of these conditions cause the aircrew to lose their situational awareness.

The Army has recognized this hazard and approved the Degraded Visual Environment (DVE) Operational Needs Statement (ONS) program to develop and test a system to solve the Brownout Landing problem to enable aircrews to operate safely in DVE conditions.

Within the Army Aviation Community, MEDEVAC has the highest risk in combat and peace time operations due to the urgent nature of the mission. Unlike other helicopter communities who can select their landing area to minimize the risk of brownout or whiteout, in order to most rapidly provide medical support and evacuate injured soldiers and civilians, MEDEVAC must land close to patient.