Degraded Visual Environment (DVE) is a term coined for environmental conditions that impair the visual orientation of a helicopter pilot during flight or landing.  These conditions include brown-out, but also white-out, night, glare, fog & mist (and any combination of these).  DVE can lead to reduced situational awareness (SA), increased pilot workload, and the partial or total loss of aircraft control.

During the Afghanistan campaign, a significant number of UK support helicopters suffered damage during landing when the visual cues used by the pilots were obscured by dust clouds caused by rotor downwash.  In response to an urgent requirement, Ferranti Technologies developed a unique system combining aircraft sensors and an intuitive 3D Conformal Symbology (3D CS) that enables the pilots to safely handle the aircraft in close proximity to the ground in extreme DVE conditions.  3D CS is delivered using the standard, in-service DNVG-24T Head Mounted Display (HMD) and has been proven both in flight and through simulation.

Work to implement 3D CS has progressed on both side of the Atlantic, with the US Army Aviation now taking the lead through their Crew Station Working Group (CSWG) progress. Through this process, the US Army Aviation have been looking at an affordable solution to improving pilot cueing and symbology as part of a holistic DVE solution.  This has involved taking, and developing further, the UK 3D CS solution, combining this with improved 2D symbology, and then integrating this into a high-fidelity simulation environment.  The US Army Aviation, using operation pilots, have flown realistic missions under DVE to evaluate usability, workload and efficacy.  It has been reported in the US Army Aviation Magazine (January 15, Pages 44 and 45) that improved 2D and 3D CS symbology, tested using the CH47F CSWG, led to an impressive 32% reduction in pilot workload and a 45% increase in SA. The Magazine also reported that the improved symbology will enter formal flight testing on the UH60 and CH47F during 2015, with a release for operational use achieved before the end of 2015.

In the UK, a decision on whether to implement 3D CS is being actively considered within the package of safety measures being implement to improve helicopter safety.