Good Kit

The specific equipment subject to the review are the Night Eyes Aviator, Binocular NVD with Photonis ‘Gen 4 Intens’ image intensifiers and a black and white or ‘Onyx’ image at the eye piece lense. The devices have an internal single cell lithium battery source or can be augmented with a dual cell battery pack in keeping with an emphasis on systems redundancy.

The first apparent distinction when handling the Night Eyes is the robust aluminium casing that encapsulates the single cell power source. Although this simplicity is useful for the initial pre-flight inspection, the afore mentioned redundant power system requires an additional battery back mounted at the rear of the helmet, offering commonality with existing NVD’s. However, the key point of difference in the casing design is the binocular style movement of each monocular image tube, replacing the traditional interpupillary distance mechanism.

The helmet mounting device enables freedom of movement in all the traditional axes, vertical, fore – aft (eye relief), tilt or pivot and the ability to stow the devices for unaided flight. The adjustment mechanisms maintain some continuity with previous designs although are not entirely intuitive and relied heavily on pre-flight drills for the development of muscle memory. The range of movement in each axis seemed enhanced and coupled with the binocular style adjustment of interpupillary distance, afforded greater potential for the creation of the optimal overlapped eyepiece image.

With the system fitted and stowed, the weight in terms of balance was bias towards the forehead and required the use of additional weight at the rear of the helmet. Whilst this is not uncommon, the stowed position of the NVD created an additional imbalance that may accelerate the onset of fatigue during prolonged unaided operations.

The removal and stowing of the lense caps is not to be underestimated as they slide off the objective lense and stay securely fastened to each monocular housing. Seemingly a low priority in design terms, but to every operator, a welcome relief in the context of cockpit equipment management.

The 4G Intens image intensifier features the ‘Onyx’ or black and white image with auto-gating. Auto-gating is the process of oscillating the power supply to the photocathode and when combined with traditional Generation 3 ion barriers, optimises visual resolution under dynamic illumination conditions. The design intent being increased contrast and reduced blooming effects commensurate with bright light sources. For the benefit of the review the technical specifications for the 4G Intens advertise visual performance in terms of the Figure of Merit*, being 1800 to 2000 and beyond.

The black and white visual image at the eyepiece lens was the sole source for any of my personal reservations. This significant departure from the norm is intended (amongst other physiological advantages) to exploit the efficiency of the human visual system in processing black and white images. And they did not disappoint. Any apprehension was quickly forgotten on first adjustment, the device seamlessly integrating into normal operations.

The Night Eyes were used over a period of weeks under low illumination with nil cultural lighting, high lunar illumination, urban environments and in close proximity to live fire. Whilst improved performance in low contrast environments was expected, the most notable enhancement to the visual image was the reduced blooming effects associated with bright light sources. The conduct of the CASA approved night fire trials required the use of portable flood lighting at replenishment helicopter landing sites. An operator’s night vision scan is instinctively modified to exclude bright light sources however this was not necessary when viewed through the Night Eyes. The normal NVD scan was maintained and most importantly the visual image surrounding high intensity sources retained sufficient clarity to facilitate image interpretation.

In terms of fatigue, the trial flights never exceeded two hours in a single night, so fatigue related factors were not subject to review.

The operational use of the PTG Night Eyes was a thoroughly positive experience with enhanced visual performance evident across the entire night flying continuum. The transition to subtly different mechanics and the introduction of black and white imagery presented no adverse issues, the technology integrating effortlessly into the NVIS environment and engendering operator confidence. Perhaps the most telling example of my appraisal was a recent reversion to older technology and the associated feelings of discomfort with the reduced visual scene. Taking a step back amplified the generational leap forward in Night Eyes technology and the associated benefits for future night flight operations.

Note*

The Figure of Merit is a measure of visual performance, determined by the multiplication of the NVD’s visual resolution (measured in line pairs / mm and established post production) by the Signal to Noise Ratio detected at the eye piece lens (Light signal exiting the device versus the perceived background noise).

Richard Butterworth is the Head of Training and Senior Night Vision Pilot for Kestrel Aviation. His aviation career spans twenty-six years with a bachelor’s degree in aerospace engineering and occupying operational and instructional roles as a helicopter pilot within the Australian Defence Force and the civil sector.