Rudimentary versions of night vision devices were first created for the military, with an infrared sensitive camera developed by Hungarian physicist Kálmán Tihanyi back in 1929.

Following significant technological advancements and breakthroughs, it was in early 1999 that night vision imaging systems (NVIS) first entered the world of aviation when a civilian helicopter operator providing emergency medical services (EMS) was permitted by the Federal Aviation Administration to wear night vision goggles (NVGs). Since that time, NVIS has become more prevalent in civil operations, with recognition of the ability of these systems to enhance the safe operation of nighttime missions. 

Owen McTeggart, UK-based Yorkshire Air Ambulance’s Chief Pilot, explained that although night flying isn’t a recent phenomenon, NVGs have significantly improved safety for pilots and the patients they fly.

“Night flying for air ambulances is not really a new thing – as long as the pilot was night instrument or night rated, they could still fly at night. NVGs for these transits to the hospital and back to base made things safer as we could now see the difference between those showers and dark hills at night.” Innovations, knowledge and training in this area continue to grow, with a consistently keen eye on safety and a desire to maximize the life-saving potential of NVIS. 

Training and procedures have always been crucial elements for safe flight, as McTeggart articulated, but without NVIS, operational availability was far less than it is today: “We mitigated safety risks when we first started flying at night by implementing training and procedures. The main thing we couldn’t do was land on scene at night, which cut our operational availability by 50 per cent in the winter months.”

He highlighted to AirMed&Rescue the perpetual importance of training and the need for this to be regularly re-evaluated: “Training is completed before signing off a member of the crew for NVIS operations and this is checked annually, with a requirement to remain in current practice.”

Risk mitigation with regulations
In addition to ongoing training, strict NVIS procedures must be followed and along with advancements in night flying techniques, stricter regulations have been necessarily implemented, as Jochen Güntner, Chief Flight Instructor and Head of NVIS Standardization, ADAC Luftrettung, reflected: “We have seen many improvements in night flying techniques over the last 37 years. The early years back in the eighties were characterized by finding quick-fix solutions that are neither feasible nor desirable in today’s highly regulated and technical environment.” 

Today the aviation community has access to the highest performing NVGs ever and most of the significant developments are related to form and function

McTeggart highlighted to AirMed&Rescue examples of procedures that are followed by Yorkshire Air Ambulance: “To land at the scene at night with NVG, we have put in place a strict survey procedure to ensure risks are not increasing from day to night. The landing site needs to be twice as big as the minimum for the day. We also look for potential landing sites on the PC/iPad before we even take off, and then do a full aerial survey with NVG and a searchlight to make sure we see the potential hazards before we commit to a landing,” he said. 

Comdt Oisin McGrath, Officer Commanding 301 SQN (Tactical & Airlift) and an NVG Examiner within No 3 Operations Wing (the Rotary Wing within the Irish Air Corps) also described to AirMed&Rescue how training and experience have increased significantly, while safety has been maintained: “Constant procedural updates, regulations changes and continual training, including two visits per year from an external training provider, ensure we operate in a safe environment.” 

Güntner confirmed the importance of frequent evaluations, which also extend to the assessment of new technologies: “We continuously evaluate the latest cutting-edge technology and are at the pulse of the development of new equipment,” he told AirMed&Rescue. “Our modern equipment enables us to fly comfortably in light conditions under which, in the past, it would not have been possible to land on scene at night. This has continuously increased our flight safety on night flights.”

Technological advancements 
There is no doubt that innovations in NVIS have enhanced operations and improved safety. McGrath shared with AirMed&Rescue details of important developments: “Newer NVIS have changed from green phosphor to white phosphor with much improved technology in the tubes which has resulted in increased FOM (figure of merit = effectiveness of the NVG).

Whether it be green or white phosphor, the increased FOM means that a much higher resolution image is being seen through the tubes. Better image intensifiers means increased acuity, and much less scintillation is experienced during times of reduced ambient lighting. Newer technology has resulted in reduced the HALO effect with increased levels of particles in the air (moisture or sand). Generally, over city operations etc. can benefit greatly from reduced HALO effect in various weather phenomenon.”

McGrath also explained how gain control is improved on the newer NVIS and why this is important: “When transitioning from dark areas, increased levels of bright lights cause a reduction in image clarity due to gain control (dimming) of the goggles. Newer technology has resulted in an improved gain control, which results in less dimming due to bright ambient lights.”

McTeggart has had experience with most generations of NVGs and confirmed to AirMed&Rescue that they are much improved today: “Our NVGs work particularly well, especially with the searchlight (Trakka), which has an NVG light mode (infra-red), so we can see the light with the NVGs, but it doesn’t blind motorists on the road next to the potential landing site. They are really good at low light levels when older NVGs would have a useless grainy picture.”

Smooth operator 
The pilots AirMed&Rescue spoke with shared how they personally find using the latest generation of NVGs. “Compared to older-generation NVGs, the latest generation goggles are easier to operate and much more helpful during VFR (visual flight rules) night flights in challenging conditions like moonless nights,” said Güntner.

“As a HEMS operator we benefit from their increased tolerance to cultural lighting that we inevitably face during HEMS flights in urban and built-up areas. At the same time, we enjoy their good image intensification in rural areas that are also part of our mission spectrum.”

McGrath said that new NVIS have added a new level to the Irish Air Corps’s flying: “Increased visual acuity and the increased gain control has helped us when flying from dark mountainous areas to city operations. Our Police Air Support crews and Marine Counter Terrorism crews continually move from extremely dark to extremely bright areas. New technology in NVIS has aided this transition,” he told AirMed&Rescue.

“Using white phosphor goggles for hoist operations and maritime operations has also helped, especially in areas with very low ambient light. There is a level of image clarity with the new white phosphor goggles that was not there with the green phosphor. These have been a great addition to our nighttime operations.”

Manufacturers’ musings
Alongside pilots, AirMed&Rescue also spoke with NVIS manufacturers, including Jeff Stubbs, Senior Vice-President of Operations and Systems Technology, REBTECH, who shared how innovations are improving operational capabilities for airborne special missions providers: “Cockpit modifications are always changing and in REBTECH’s case we are continually developing new filters to keep up with the ever-changing goggle capabilities, reducing AOG (aircraft on ground) time, and streamlining maintenance procedures.” 

K Kirkendall, Director of Training, Aviation Specialties Unlimited (ASU), also spoke of how training is changing in light of identification of risks: “As we have studied the root causes of many aviation accidents there has been a tremendous amount caused by spatial disorientation while operating in reduced visual environments. AT Systems has created a training device that has targeted some of our most vulnerable flying environments during the day and at night.”

Kirkendall continued: “Today, the aviation community has access to the highest performing NVGs ever and most of the significant developments are related to form and function – improving the operators’ experience. Lighter and easier-to-use goggles and accessories let operators focus on safely and effectively performing their mission and avoid chronic neck and back issues. The US Department of Defense announced recently that ASU is part of a pilot program to accelerate the procurement and fielding of widened field of view goggles with increased resolution and reduced weight.” 

In terms of how these innovations are improving safety and comfort for pilots, Stubbs said that now that safer in transit operations have been established, REBTECH is focusing on the critical phases of flight – takeoff and landing.

“As our military programs have matured, we are moving some of our key products into the civil sector,” he told AirMed&Rescue. “These products will provide superior illumination on the landing zones, aircraft zone lighting while also providing easier recognition from other aircraft in the air. These modifications will provide the flight crew with more security in and out of unimproved landing zones as well as in transit flight.” 

Kirkendall said that safety is always the priority: “Since I transitioned to ASU from the military one thing that stood out to me was the company’s drive to continue to find night vision solutions to save lives.” The focus of what we work towards at ASU is to find ways to increase the safety of the aviation community.”

He explained more about ASU’s work in this area: “We spend a lot of time demonstrating and training the strengths of why we wear NVGs. A search and rescue pilot conducting hoist operations in a dark area that may be adjacent to rising terrain requires precision hovering capabilities. We want those abilities enhanced by providing the best night vision scanning solution out there like the 2376 FOM white phosphor NVGs. Illuminating the dark horizon scan with white phosphor, while providing the peripheral capability to read radar altitude and observe cockpit cues, is really second to none right now.”

Future improvements and innovations
Alongside newer NVIS having progressed from green to white phosphor, AirMed&Rescue asked Stubbs and Kirkendall what the industry can look forward to next in terms of future innovations. “The talk for years has been overlaying thermal images over the NVIS goggle image. But after 34 years in the NVIS world, it’s time to start focusing on complementary systems to team up with NVG and focus on decreasing the flight crew workload,” said Stubbs.

“REBTECH is in the process of designing a new concept that we’re not yet ready to discuss, but stay tuned!”
“In my opinion, the next innovations for aviation night vision will incorporate higher-performing image tubes, into lighter-weight systems with increased field of view,” stated Kirkendall.

“In the future, our focus will be on reducing even more weight on NVGs to make the pilot’s scanning abilities even more efficient and less fatiguing. Future users of NVGs will be able to choose from standard binoculars at a reduced weight or wider field of view (four tubes) at nearly the current binocular weight.”

Future users of NVGs will be able to choose from standard binoculars at a reduced weight or wider field of view (four tubes) at nearly the current binocular weight

Certification challenges
AirMed&Rescue spoke with Tim Lysons, Engineering Manager, Oxley Developments, who has 21 years’ experience in NVIS design, about the main challenges faced when certifying new NVGs and NVIS for cockpits.

He said: “In my experience the main challenge with designing and then certifying an NVIS is the difference between the specifications and what is actually required by the particular configuration of the aircraft cockpit. It is possible to design a system which entirely meets the requirements, only to find that for a particular arrangement, it becomes unusable by the pilots. Reasons for this could be the relative position of certain instruments, eg, warning indicators grouped together or in the eyeline, or an imbalance in the overall system level, which can be compounded if more than one supplier is involved in providing equipment.”

He continued: “The technology available for NVIS such as LEDs and IR emitters, filters and coatings has come a long way in the last 20 years, but the standards governing the design of the systems, such as MIL-STD-3009, have not been updated alongside. Organizations such as the SAE provide guidelines and specifications to aid in the design of external lighting such as dual mode position lights, but even then it is difficult to cover every possible eventuality and application where NVGs are used, and therefore it is the responsibility of the supplier and the end user to work together to create a system which is successful for a particular application which, although based on requirements and guidelines, should be fine tuned by trial and verification testing.”

Safety and strict procedures continue to boost NVG capabilities
Regular training and evaluations of technology and innovations are key and as NVIS has become more advanced and widespread, stricter procedures have been implemented and regulations and training have doubled. Pilots have been able to take flying to the next level with the use of NVIS, including enhancements in FOMs, clarity and gain control.

Ultimately, improvements in this area have enhanced the safety of the aviation industry. Manufacturers are striving to make NVGs and accessories lighter and easier to use. It all comes back to safety, with innovations making NVIS more efficient and less fatiguing for operators while widening vision and increasing resolution, providing sharper, intensified images and providing clarity in areas with low ambient light.

The current generation of NVG users are preferring white instead of green phosphor and future innovations will look to further reduce weight while widening the field of vision and continually improving safety. Manufacturers and pilots are regularly evaluating new and existing technologies to remain at the cutting edge and with access to the best ever performing NVGs and innovations pending, not only is the aviation industry increasingly efficient and sophisticated, so too is safety enhanced; which is the bottom line.