NVG (ANVIS, AN/AVS) for HEMS, which is best USA vs. Europe vs. Israel?

[Iefan]

Hi All

Please could I request assistance from the members of this forum.

We are in the process of starting a NVG (ANVIS, AN/AVS) program on our aeromedical helicopters to improve the safety, efficiency and effectiveness of our operations.

At the moment we operate unaided to urban well lit helipads as well as to rural hospitals that have some form of lighting, not necessarily located on the helipad though (i.e. flood lighting from surrounding building/street lighting etc).

In general the hospitals are located in or near small towns so there is some ground lighting, and our en route phase covers countryside with some scattered ground lighting from towns, industrial areas, villages, homesteads, farms, roads, etc

Considering the above environmental lighting conditions I have approached a number of suppliers from the USA, Europe and Israel for NVG (ANVIS, AN/AVS) solutions that will best meet our requirements.

Below is a list of the NVG (ANVIS, AN/AVS) solutions which I have available at the moment and which are permitted for export to South Africa.

USA

1.
ITT EXELIS AN/AVS-9 (F4949)
Generation 3 image intensifier tubes MX 10160 F9800K
Figure Of Merit (FOM) of 1400
In the unlikely event that the State Department approves a FOM of 1600 then the Pinnacle F9800YG Photocathode Sensitivity of uA/lm of 1800.
Field of View 40 degrees
ITT Exelis - Image Intensifier Tubes (http://www.exelisinc.com/solutions/Image-Intensifier-Tubes/Pages/default.aspx)
ITT Exelis - AN/AVS-9 Aviator's Night Vision Systems (http://www.exelisinc.com/solutions/AN_AVS_9-Aviators-Night-Vision-System/Pages/default.aspx)

2.
L-3 Model AN/AVS-9 FOM 1400, Class B M949
Generation 3 image intensifier tubes
FOM of 1400
Photocathode Sensitivity of uA/lm of 1350-1550.
Field of View 40 degrees
10160/M890 (http://www.insighttechnology.com/l3-products/m890av-cs)

Europe

3.
Helimun
Image intensifier tube from Photonis XR5
FOM 1600-2000
Photocathode Sensitivity of uA/lm 800
Field of View 40 Degrees or 60 Degrees
XR5 Image intensifier (http://www.photonis.com/en/nightvision/75-xr5.html)
OIP Sensor Systems NV (http://www.oip.be/helimun.asp)

4.
Fenn NG 2000A
Image intensifier tube from Photonis XR5
FOM 1600-2000
Photocathode Sensitivity of uA/lm 800
Field of View 47.5 degrees
XR5 Image intensifier (http://www.photonis.com/en/nightvision/75-xr5.html)
Product » Fenn Night Vision (http://www.fenn-night-vision.co.uk/product/nvg/ng2000a)

Israel

5.
New Noga Light (SDS) NL-93A
Image intensifier tube from Photonis XR5
FOM 1600-2000
Photocathode Sensitivity of uA/lm 800
Field of View 40 degrees
XR5 Image intensifier (http://www.photonis.com/en/nightvision/75-xr5.html)
NL-93A (http://newnogalight.com/index.php?option=com_content&view=article&id=22:nl-93&catid=1:observation-systems&Itemid=17)

My questions:

1.
For helicopter air ambulance (HEMS) operations in the environmental conditions described above, which image intensifier listed above would suit our operation best?

2.
Approximately how many electrons ( as a percentage ) that are transmitted from the Photocathode towards the MCP are lost to the ion barrier film.

If we take the MX 10160 F9800K, it states a PR of uA/lm of 1800, but how much of that enters the MCP?

Is this why images produced by the XR5 are comparable with Gen III images, due to electrons lost to the Ion Barrier Film?

3.
I guess fundamentally I would also like to know if an American Gen III tube limited to a FOM of 1400 (if we get lucky 1600) without the auto gated power supply but with a uA/lm of 1350-1550 would outperform an XR5 with auto gated power supply and a FOM of 1600 in very dark conditions?

And if so, would an XR5 with a FOM of 2000 do any better against the Gen 111 with a FOM of 1600?

4.
Can anyone rate the optics and housings of the goggles above, and indicate which would be the preferred option?

5.
Are there any negatives to the larger Fields of View? I.e. 60 Degree Field of View offered by Helimun? Why would one want a 40 degree Field of View if you could have 60 Degrees?

6.
Any recommendations on which helmet to pair with the above goggles?

7.
Anything else I should be considering?

My objective is to provide the very best NVG (ANVIS AN/AVS) equipment to the aircrews so any answers/comments/suggestions to achieve this would be very much appreciated.

Finally if you were in my shoes which would you choose, with which helmet and why?

Looking forward to your replies, all inputs welcomed.

Iefan Blake

[[email protected]]

Iefan - it will be interesting to see what replies you get as you ask some very technical questions that probably only the manufacturers have the answer to.

Probably any of the products on your list will be suitable and the only way of deciding which one is best would be to try them all and see for yourself.

It is important that you get your aircraft lighting (internal and external) set up properly - military would go for black light steerable spotlight and floods but a white light/NVG mix is very workable in non-tactical scenarios.

You might also want to consider the weight and the distribution of that weight when selecting your NVGs and helmet combination, as a well fitting helmet with good weight distribution will help prevent fatigue and sore necks amongst your pilots.

Ultimately your choice will be limited by the ITARs and what the DoD let you have but gen 3 are still very good goggles.

Not entirely convinced about the 60 deg FOV - probably special ops are the only people to get that sort of technology and it might just be a manufacturer's fudge by putting a different (wide angle and therefore distorting) objective lens on the front. Again, try before you buy.

[hueyracer]

Take into consideration the maintenance side of the product...

If one company offers overhauling and service in 48 hours-and the other needs 48 days, i would know which way to go...

[ARRAKIS]

Iefan,
a few points.

Are there any negatives to the larger Fields of View? I.e. 60 Degree Field of View offered by Helimun? Why would one want a 40 degree Field of View if you could have 60 Degrees?
The FOV is increased by the optics, so 1.5x wider FOV means also an image resolution (in lp/mm) decreased 1.5 times. A point usually omitted.

Most of the questions you are asking are very technical. Even getting the answers will not help you a lot, as the parameters you are asking for are measured at a given lighting level. When that changes (brighter or darker), the parameters are also changing. The question is how.
As crabb pointed out, IITs are just a part of the problem. There is also weight, mount, etc...
One more point. You should be able to get XR-5 with gated power supply, whereas AFAIK US made gated gen III IITs are ITAR restricted.
Gen III IITs will perform better in low light condition than XR-5.

Last point to consider is of course cockpit NVG compatibility. The IIT choice may have an impact here.

Arrakis

[heloguy412]

My biggest concern with regards to NVG operations isn't any of the concerns brought out by the other posters. All systems are good and will do the job that is required. My biggest concern is the amount of money that will be expended training to an acceptable standard and then more importantly maintaining competency. Notice that I said competency and not currency. NVG use is a highly perishable skill and you can't just strap them on and go flying. Is your company going to outlay the required money for this project fully or are they going to half ass the training and leave the pilots to their own devices? That is the question I would be asking. As for the conditions of the areas you are describing, they sound suitable for unaided operations as long as they have been recce'd during the day. Might want to concentrate on that aspect of the operation vice NVG's.

Former NVG Instructor Pilot.

[vaqueroaero]

I have flown with goggles that have 60 degree FOV and to be honest found no noticeable difference when compared to the standard 40 degrees, so I wouldn't make that a major purchase decision.

The most important thing is to make sure that the goggles and cockpit lighting are compatible. We found out the hard way that when they are not life can get very 'interesting'.

As far as helmets go that is pretty much personal preference. I use an Alpha Eagle, which I find very comfortable.

[HueyLoach]

Iefan,

One important question is what minimum performance level for the NVG system the aviation authority is going to authorize for these operations.

Are there any required published standards? Or is like in the US, the FAA for many years being well behind the industry in NVDs matters.

I am only familiar with ANVIS-6 and F4949 so I cannot make any comparissons in terms of preference or performance. Like somebody wrote above, you have to consider also training and support.

[[email protected]]

A very good point made by heloguy412 regarding training - it is vital to train and maintain those skills.

Are you going to operate single pilot on NVD or do you have another crew member who will also assist. Single pilot NVG takes the risk level up another notch, especially into unprepared sites and you need some robust procedures to deal with tube failure, deteriorating weather and IIMC.

The most disorientated I have ever been was intermittent IMC on NVG.

As vaqueroaero says - your lighting (as mentioned earlier) in the cockpit has to be properly set up. Stick-on flood lights are nowhere near as good as proper NVD compatible instrument lighting and that has to include ALL the cockpit (radios, IFF, nav kit etc) not just the flight instruments.

[Iefan]

Thank you all for your prompt replies and valuable inputs.

[email protected]
Probably any of the products on your list will be suitable and the only way of deciding which one is best would be to try them all and see for yourself.
This is very reassuring and I was hoping that this would be the case...guess a visit to the manufactures is the answer. Any thoughts on how to standardize the testing of the goggles as the ambient lighting conditions and environment will not doubt be different at each of the facilities?

ARRAKIS

Last point to consider is of course cockpit NVG compatibility. The IIT choice may have an impact here.Thank for this ARRAKIS. We intend to carry out an approved NVG cockpit modification. Out of interest I noticed the following: Minus Blue filters for cockpit lighting compatibilityOIP Sensor Systems NV (http://www.oip.be/helimun.asp)
Would you by chance know what this means? Does it imply that less or no cockpit modification is required?

hueyracer-
If one company offers overhauling and service in 48 hours-and the other needs 48 days, i would know which way to go... good point, thank you will keep it in mind.

heloguy412-
Notice that I said competency and not currency.
Thank you for the valid points heloguy412. Once our aircrews have completed their training, how regularly ( just a ball park figure ) would they need to fly on the NVG to maintain competency? Would mandating a NVG training sortie once a month irrespective of NVG missions flown during that month address this issue?

vaqueroaero-
I have flown with goggles that have 60 degree FOV and to be honest found no noticeable difference when compared to the standard 40 degrees, so I wouldn't make that a major purchase decision.thank you, just the kind of feedback I was hoping for.

HueyLoach-
One important question is what minimum performance level for the NVG system the aviation authority is going to authorize for these operations.Thank you for the relevant points. Its a new area for our CAA, so I believe they will take guidance from the FAA and approve operators on a case by case basis.

[email protected]

Are you going to operate single pilot on NVD or do you have another crew member who will also assist. Single pilot NVG takes the risk level up another notch, especially into unprepared sites and you need some robust procedures to deal with tube failure, deteriorating weather and IIMC.Good points again Crab. We are going to follow the American model and equip the medical crew with NVG.

What would be typical procedures used to mitigate the risk of tube failure, deteriorating weather and IIMC?

Thank you again for all the advise and inputs
Best regards
Iefan Blake

[ARRAKIS]

Minus Blue filters for cockpit lighting compatibility
Iefan,
look for MIL-STD-3009. It should be available on the net. It will give you some idea what is it all about. Long story short, you are adapting the goggles AND the cockpit making them compatible together, by filtering the NVD and the cockpit lighting. The filter on the goggles is your "minus blue" filter.
GaAs Gen III tubes are better here, as anyway the are not very sensitive below 600 nm, and by filtering them you are loosing less light than in the Gen II case.
Look for information about Class A and B differences.
Sometimes the cockpit will not be enough (some nasty reflections from outside elements of the helicopter). Another question - just the cockpit or also the external lights?


Arrakis

[[email protected]]

Here

http://www.gd-itronix.com/upload/pdf/DOD-STD-3009.pdf

Go to appendix C to start with.

[GS Pilot]

I'll offer my opinion as a relative newcomer to NVG flying.
4 years/ 300 hrs of NVG time with ANVIS 9 Pinnacles, can't compare them to other models.

No matter how well lit the LZ's are, NVG's will substantially decrease risk during the enroute portion of your operation, especially in weather.

Helmet comfort is subjective, but I've worn 3 brands and 2 work for me.
Gentex: They suck. Tried about 4 or 5 with different liners. They all felt horrible after an hour or so.
Alpha 200: can wear it all day. Love the leather lining. Held up well for 12 years.
MSA Gallet LH250: also very comfortable with a lighter feel and less bulky NVG visor compared to the Alpha. Chin strap is crap, already coming apart after 2 years. Get the Oregon Aero ZetaLiner. It's very nice.
I like the Gallet best because the clear visor is close enough to my face that I can use it with NVGs. Something I never really thought about until a co-worker took a large bird in the face during a day flight. His visor was down but impact nearly knocked him out and after he recovered from inverted flight he only had a few lacerations to his face and sore muscles. Imagine a vulture impacting your goggles at 130 kts with only your eyelids to protect you.....goodbye eyeballs.
I always wear earplugs so noise attenuation is about equal.

Training/Currency:
I respectfully disagree with Heloguy412 and others in this matter. NVG flying is not complicated, it requires a minimal amount of hours to become proficient, and it is not nearly as perishable a skill as IFR or VR LongLine. Study the materials, understand the limitations, fly a few hours with an experienced instructor who can demonstrate those limitations. Good to go. Like anything else, walk before run. I'm sure that will seem flippant to some, but it has been my experience.

Good luck with the process.

[[email protected]]

GS pilot - if all you are doing is using your NVG for transit flying at a safe height then NVG may seem straightforward. If you are doing low level, poor weather, unlit and unrecced sites then constant training is required.

Your stats (4 years, 300 hrs NVG) indicate you are flying an average of 75 hours a year which is somewhere in the region of 6 hours a month. That is an acceptable level of currency, especially for cruise flight. You don't say if you are operating single or twin pilot.

Try not doing any for 3 or 4 months and then go straight into a poor weather, low level transit to an unlit and unrecced site.

[Megawart]

I suspect that anyone who claims that NVG flying is not complicated is really only using them for Nav assist at night. If you are required to undertake missions at night to exactly the same standards as day (poor viz, low level, risk of inadvertent IMC, confined areas, hovering with limited references etc etc etc) then NVG will require at least a couple of hours of training every month.

[busdriver02]

"missions at night to exactly the same standards as day"
To do this on NVG will absolutely require recurrent training. Low illum nights require a completely different composite cross check than high illum nights or day flights. Flying over low contrast terrain on a low illum night is damn near an instrument maneuver, except you're doing it under VFR.

[Iefan]

My apologies for the belated post, I've been out the office.

ARRAKIS and [email protected] thank you for the document, I'm going to go through it in the next couple of days. I will ensure we address the external lighting, thank you for highlighting its importance.

GS Pilot- thank you for your thoughts and the information on the helmets. I was favoring the Alpha helmets, but you make a very good point about the visor on the Gallet. Luckily we have these protecting us....
Polycarbonate vs Acrylic Plastic - YouTube
Thanks for the tip on the Oregon Aero ZetaLiner.

GS Pilot, [email protected], Megawart and busdriver02- thank you for your posts regarding training and currency.

Its evident from your insightful posts that different training and currency requirements are applicable depending on the typical mission profiles flown by your organization and what weather conditions such missions are permitted to take place in. I understand the point of view of the various posters.

I would still like to know what would be typical procedures used to mitigate some of the risk of tube failure, deteriorating weather and IIMC?

Tube Failure
-Limit operations below a certain height or for certain higher risk missions to two pilots
-Limit operations to a minimum height AGL to allow for recovery procedure if tube fails?
-Limit operations to a minimum cloud base and vis?

Deteriorating Weather
-Institute a rule that if a specific height or speed can no longer be maintained due to lowering cloud base or visibility aircraft diverts and routes into better conditions or if not possible lands?

IIMC
-IIMC training
-Conservative cloud base and visibility planning minima for mission?

Please add more measures/procedures with which to manage risks introduced by NVG opertions.

Thank you
Iefan

[MightyGem]

Make sure that you get the aircraft's Certification/Flight Manual sorted out. Our Flight Manual states that if the IR landing light or the Rad Alt are u/s, then NVG flight is forbidden.

So, technically, if one of those is u/s, we would have to fly around the hills of Wales without using goggles rather then see where we're going. :ugh: :ugh:

[[email protected]]

Iefan - tube failure mitigation = abort to above 500 ft agl or higher (for obstacle avoidance) rectify problem (if possible) and either resume or abort or continue as you did before you had NVG.

We are allowed to reversionary night fly (ie non-NVG) VFR in UK (military) at or above 500' msd (minimum separation distance).

That leads onto weather limits for the mission - our training limits are different depending on whether or not we have an IFR recovery option - 400' if so, 700' if not - we effectively don't have weather minima for SARops but we have 2 pilot IFR capability. You might want to specify minimum light levels and ensure you have access to met information that provides forecast light levels. NVG is easy on a bright night but down at 1 millilux and below it is a completely different story.

IIMC - again we come back to weather limits for NVG flight - if you set sensible ones and actually stick to them you shouldn't have a problem. if your pilots are prepared to take extra risks to 'save lives' then you will probably end up in the same situation as US HEMS - ie with a poor safety record.

The best option would be for 2 pilots, both instrument rated and a helicopter with a good IFR/icing clearance. Then add sensible operating limits and remove commercial pressure and you will have a pretty safe operation. However, all that comes at a cost so inevitably there will be compromises made.

Since you are operating HEMS and single pilot, I would suggest 700' cloudbase and 3 Kms vis with a minimum of 2 millilux.

Out of interest, we are using XR5 tubes which are an improvement both in low light levels and in high gain situations over the Gen III tubes. Also we don't use visors with NVG due to distortion and misting issues.

[ARRAKIS]

Out of interest, we are using XR5 tubes which are an improvement both in low light levels and in high gain situations over the Gen III tubes.
Out of curiosity, autogated XR-5?, and what type of Gen III? Being produced for 30+ years, there are Gen III and Gen III. IIRC, EEV stopped manufactiring them in the UK in the mid 90s.

Arrakis