Rotary wing brown-out symbology: the DVEST test

Military helicopter operations encounter degraded visual environments (DVE) on a regular basis. A DVE exists when conditions of low visibility, including those caused by rotor downwash in sand/dust ("brown-out"), snow ("whiteout"/ snowball) or water, obscure both horizon and terrain features. DVE conditions have contributed to the loss of numerous helicopter crews and vehicles in desert operations, including a CH-146 crash during take-off. In Canadian helicopter operations over the past 25 years, "snowball" related events (2 accidents and 54 incidents) outnumbered brown-out related events. A NATO Task Group suggested that specific landing symbology systems could provide an immediate short-term solution that will improve situation awareness and reduce the occurrence of mishaps. This paper describes two symbology systems that were developed and the planned evaluation of these under the Degraded Visual Environment Solution for TacHel (DVEST) Program.