Night vision imaging system (NVIS) technology has been around for several years, but until recently it has been limited mostly to military applications. NVIS is now developing a significant critical mass in several specialised domains of aviation, including helicopter emergency medical services (HEMS) and airborne law enforcement. “Although law enforcement and EMS are the biggest civil users of NVIS in the US, they are definitely not the only users,” said Jeff Stubbs, Senior Vice President of Operations and Systems Technology at REB Technologies. “Recently, firefighting has become more involved as well as crop sprayers – it is more economical to spray when the wind is at a minimum – airborne reporters and university flying programmes. The added safety of NVIS benefits a wide range of users.”
Yet NVIS technology alone is not enough to ensure safe NVIS operations. Civilian operators wanting to experience the benefits enabled by the adoption of NVIS have a wealth of requirements to which they need to conform, and it is important that they be familiar with such requirements in order for NVIS technology implementation to be a smooth and fruitful experience.
The NVIS crew
The first thing to be noted is that although NVIS operations are often single pilot, there is also a requirement for the minimum crew to be composed of one pilot and one NVIS technical crew member. This is always the case under European Aviation Safety Agency (EASA) when conducting operations to/from a HEMS operating site, while it is optional in certain circumstances under the Federal Aviation Administration (FAA), because in the US there is no need for an NVIS crew member when departing from or landing to an ‘improved area’.
in the US there is no need for an NVIS crew member when departing from or landing to an ‘improved area’.
“Many operators are approved to fly single pilot NVIS. However, they will typically be restricted to take-off and landing at improved airports or helipads,” said Adam Aldous of Night Flight Concepts. “The restrictions will be listed in the flight manual supplement for the night vision goggles (NVG) lighting supplemental type certificate (STC) as approved by the FAA. Typically, for unimproved landing sites, there is a requirement to have two trained persons wearing NVGs to assist in obstacle avoidance and increase situational awareness. This is the distinctive case of single pilot EMS operators where one of the medic crews is also wearing NVGs and has been properly trained.”
In the US, for the most part, EMS and law enforcement aircraft are single pilot. “In the EMS world, in a Bell 206/407 for instance, the aircraft will be equipped with a single pilot, a nurse and a paramedic all wearing NVGs. Generally, the nurse or paramedic simply assists the pilot, as needed, when landing in an unimproved area,” explained Stubbs: “In the law enforcement community, in many operations it will be a single pilot only, while urban area airborne law enforcement may employ a pilot and tactical officer that is working with moving maps, addresses, and communication with ground officers. EMS typically flies under Part 135, while law enforcement may fly under Part 91, Part 135 or public service depending on the mission. The authority is derived under their particular operations specifications.”
Improving visibility at night
NVIS are being used for improving safety margins at night but without allowing for lowering the night visual flight rules (VFR) minima. “The use of NVGs is a significant safety feature, but should never be used to lower the minima. We find that most pilots/crews can become uncomfortable returning to unaided night flight after use of NVGs,” noted Stubbs.
NVIS operations are permitted only for night VFR. Operators must comply with the ceiling and visibility requirements of the applicable regulations and their operational approval/operations specifications and cannot change the type of weather (night VFR to IFR (instrument flight rules), as an example) they are permitted to fly in. “Under FAA regulations, Part 135 operators must comply with Part 91 but also have VFR ceiling and visibility requirements published in their operations specifications. NVGs dramatically improve situational awareness by enabling the crew to see the terrain and obstacles as well as changing weather patterns. They also reduce stress and workload due to the increased situational awareness,” pointed out Kim Harris of ASU – Aviation Specialties Unlimited.
There is a specific protocol that NVIS operators need to develop before being granted an approval as the aircraft lighting must be modified for NVIS compatibility. “In new aircraft, much of the NVIS modifications can be done by the aircraft Original Equipment Manufacturer (OEM). Equipment that is added by a completion centre or the operator require modification which is done by installing an NVIS Supplementary Type Certificate (STC),” said Harris. “The NVGs to be used must be listed as approved in the NVIS STC flight manual supplement (FMS). In the past, NVGs were listed by part number and that still applies. However, new NVGs are produced under TSO C164a and so the FMS may authorise any TSO NVG to be used. This depends on the STC holder.”
NVIS implementation requires, first of all, top management buy-in
NVIS implementation requires, first of all, top management buy-in, and once this is in place it is important to start discussions with the local civil aviation authority (CAA), who will provide guidance on their requirements. “From that point on, while an operator is working on finding a NVIS modifier for the aircraft – as well as training and goggles – the operator can be working with the CAA in the background so the entire package comes to fruition at the same time,” said Stubbs. “Once discussions with the CAA have started, an operator should begin the due diligence on working with the aircraft modifiers. This requires providing detailed pictures of the instrument panel, avionics stack, overhead (anything that lights up, get a picture) and asking the modifier how it would propose to modify the aircraft.”
“Some modifiers simply add flood lights and post lights and need to rewire portions of the aircraft. Consideration should be given to how this would affect the organisation’s ability to sell the aircraft in the future,” Stubbs added. “Other modifiers internally modify all of the equipment and in this case the operator must have spares to support flight operations when the units are out for repair. We often notice that a company selects the modifier solely based on price and the solution does not match their organisational needs or expectations.”
There are specific considerations to make with regard to the lighting arrangement of NVIS aircraft depending on whether LED, traditional incandescent or infra-red (IR) lights are being contemplated. “LED aircraft lights present their own challenges and advantages,” said Harris. “LED lights emit energy in a narrow band, typically just on the edge of the spectrum that the NVGs are sensitive to. LED lights used in a searchlight are nearly useless for their intended function of illuminating terrain and obstacles at a distance that provides the flight crew time and space to see and respond to hazards. LED landing lights, skid lights, load lights all are a great asset when using NVGs because they provide great-unaided visibility when looking under and around the NVGs, but LED lights have minimal negative impact to NVG performance.” In contrast, old-fashioned incandescent searchlights very dramatically enhance the capabilities of the NVGs. “An incandescent searchlight emits a great deal of IR energy that enhances the effectiveness of NVGs. The light energy diffuses outward from the main beam of light which provides a great deal of visibility to the crew, increasing situational awareness,” he said.
According to Harris, IR searchlights should not be installed or used on civil aircraft, the exception being for law enforcement aircraft that have a requirement for covert operations. “IR searchlights are not as effective in illuminating obstacles or providing situational awareness, they do not provide visible light the crew can use when manoeuvring close to the ground and other aircraft not equipped with NVGs cannot see IR lights. Moreover, they can damage the retinas of personnel on the ground. Conversely, they require little or no training to use because they are so weak,” he says.
Once a modifier has been selected, a benefit may be derived from the fact that typically, a modifier is able to help the operator with goggle and helmet recommendations. It should be noted that after the initial implementation, the NVGs must also be recurrently inspected in accordance with the requirements in the operations specification or, under EASA rules, the approved operations manual.
As a modifier might also work with an NVG school, it will probably be able to help in the training search process as specific regulatory requirements apply also with regard to flight crew training, qualification and recent experience. “Under the FAA, CFR Part 61.31(k) outlines the required ground and flight training requirements in order to act as pilot in command of an aircraft while using NVGs. In addition, CFR Part 61.195 also identifies the requirements for an individual to be issued an NVG instructor endorsement,” explained Aldous.
It is also vital that training be focused on NVG use in a civil airspace environment and a civil flight profile
“Pilots have several NVIS flight training schools available, and simulators have now added NVIS capability. It is important that individual operators decide on what fits best with their organisations in terms of whether conducting training abroad, training on the operators’ own aircraft at their own facilities or even conducting training with the OEM,” added Stubbs.
It is also vital that training be focused on NVG use in a civil airspace environment and a civil flight profile, according to ASU’s Harris. “Instruction provided by a pilot with extensive military experience but without civil NVG flight experience is incomplete,” he told AirMed&Rescue. “Military training is focused on tactical operations, preparing to operate in hostile environments where any light emitted from the aircraft makes you a target to hostile forces. In a civil, non-hostile environment, white light is a pilot’s best friend on NVGs. The use of white light while operating NVGs is not intuitive and must be taught by an instructor who understands how to optimise NVG performance using aircraft searchlights and other lighting.”
Night vision technology certainly holds great promise for the future of emergency service provision, but it is no doubt vital that those operating the flights are current with the latest training and regulatory requirements.