Night vision goggles have been in use for many years and limitations in their use have been well studied through
training research and flight experience. However, advances in technology have led to improvements in NVG display
capabilities and in some cases helmet mounted display (HMD) technology has begun replacing NVG systems. These
advances have led to an increase in the complexity of imaged scene content, thus requiring a greater level of cognitive
effort for interpretation, especially when compared to the images provided by current NVG systems. In some cases the
complexity of visual imagery has resulted in systems not being classified as operationally suitable. This presentation
will focus on a few of the problems noted while testing some of these advanced systems. Topics will include: added
complexity of imagery in wide-field-of-view (WFOV) NVG systems, effects due to imagery created by sensors
displaced from the normal eye position (increased interocular separation), effects due to imagery projected onto seethrough
visor designs, and effects resulting from cockpit design/geometry (e.g., location and design of large-format
head-down displays, and the position of structures such as window frames). Training concerns and potential mitigation
strategies for HMD design concepts will also be covered. The issues discussed are important for manufacturers to
understand during the early design phase, and for testers to understand during developmental or operational testing.
Since vision is by far the most important sensory input for spatial orientation, it is important to obtain the best visual performance possible from any device. To determine whether current devices were being properly adjusted, visual performance data were obtained from USAF NVG aircrew members after they (1) adjusted the goggle using their usual method of adjustment, (2) used the NVG resolution chart to augment their usual method, and (3) used goggle-adjustment procedures learned in the training class. Results show that without a standard target or procedures, aircrew members were not able to obtain optimal goggle performance - the average visual performance was 20/53 for the 218 aviators in this study. For the 158 aviators who also used the standard target with their usual procedure, there was a significant improvement (average of 20/47). Finally, significantly better goggle performance (average of 20/37) was obtained when 48 aviators adjusted their goggles using procedures learned in the adjustment training class. While these data support the importance of preflight adjustment of NVGs, they represent visual performance under optimal, controlled conditions. It is important to remember that visual performance under actual flight conditions can be significantly impaired with reduced illumination, low contrast levels, improper cockpit lighting, and poor transmissivity of infrared energy through the transparencies.
KEYWORDS: Weapons, Heads up displays, Night vision, Control systems, Forward looking infrared, Head-mounted displays, Light sources and illumination, Head, Visualization, Navigation systems
The addition of night vision devices (NVDs) to military fixed wing aircraft has resulted in the most significant increase in operational capability since the advent of computer controlled weapon systems and flight controls. This paper will briefly discuss the operational enhancements and limitations afforded by the application of NVDs to fixed wing aircraft, and then more thoroughly discuss a few of the lessons learned from testing and employment as seen from the eyes of operators. For the purpose of this paper, the term NVD will refer to both night vision goggles (NVGs) and forward-looking infrared (FLIR) systems. Other aircraft systems contributing to the night mission will be briefly discussed later in the paper.
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