Civil Aviation Use of NVG

Presented by:

Transport Canada

Operational Standards

Division

June 30, 2005

OUTLINE• NVG Basic Concepts• NVG Characteristics • Human Factors• NVG/Aircraft Integration• Operational Considerations for

Civil Certification

Why Use NVG?

• Human visual performance under night illumination levels very poor - 20/200 (full moon) or worse.

• NVG - Enhanced visual performance - 20/30– Better spatial awareness– Improved situational awareness

NVG Flight

• NVGs do NOT turn night into day!

• Is NVG-aided flight considered to be enhanced night flight?

• Or is it more appropriate to consider it degraded day flight?

Basic Operating Concept

• NVG - Used to view the outside world

• Unaided Eye - Used to view the cockpit

Anatomy of NVG

Objective Filters

• Prevent certain wavelengths from entering image intensifier

• Allows use of properly filtered lighting to illuminate cockpit for viewing underneath goggles– Class A: blocks below 625 nm (blue/green)

– Class B: blocks below 665 nm (blue/green/reduced red)

– Class C: incorporates notch filter to permit viewing of specific wavelength

Spectral Response

CLASS A/B/C

Automatic Gain Control

• Designed to maintain image brightness and protect tube from excessive light levels.– Automatic Brightness Control - Provides

consistent output brightness by control of microchannel plate voltage.

– Bright Source Protection - Protects the image intensifier tube by control of photocathode voltage.

Gai

n

(%)

Illumination (mlux)X

00

100

Constant brightnessregion

NVG adjusts to ambientconditions from overcaststarlight to dusk/dawn

Gain is constant, and noise increases as illumination decreases

Automatic Gain Control

Airborne Complex Light Scene

NVG Performance Metrics

• Tube Gain - Ratio of intensifier tube output brightness (in foot-lamberts) compared to illumination of the input (in foot-candles). – Gen III typical value: 25,000-60,000 fl/fc or 2500-6000

fl/fl

• System Gain - Ratio of output brightness to input brightness (both in foot-lamberts) for the complete system.– Gen III typical value: 2500-6000 fl/fl

Signal (electrons produced by ambient light)

Noise (stray electrons)

Signal to Noise Ratio

• Measure of image intensifier performance• Defined as:

Stronger signal produced by:– More ambient light

– More sensitive photocathode

• SNR highly dependent on ambient light levels

• Gen III I2 tubes (1995)

• Photocathode sensitivity:

– SNR of 16

– 1000 A/l

• MCP channel diameter:

– 11 microns

• Tube gain: 25,000 fl/fc

• System gain: 2500 fl/fl

• Resolution: 36 lp/mm

• Gen III I2 tubes (2000)

• Photocathode sensitivity:

– SNR of 25

– 1,800 A/l

• MCP channel diameter:

– 6 microns

• Tube gain: 60,000 fl/fc

• System gain: 6000 fl/fl

• Resolution: 64 lp/mm

Generation III - Improvements

Gen II

Gen III

Spectral Response - Gen II vs. Gen III

NVG Low Light Capability Comparison

Generation I, II and III Comparison

NVG HUD

• Display flight and navigation information

• Eliminates need to look under the goggles for aircraft system and flight information

• Increased safety

• Enhanced situational awareness

NVG HUD Image

Human Factors

• Visual Performance

• Fatigue

• Spatial Disorientation

• Complacency

Visual Performance

• NVG FOV is 40 degrees

• NVG partially obstruct view of cockpit

• Visual Acuity is generally 20/30 at best– Decreases in low light– Decreases as contrast in scene decreases

• Monochrome image

Vision Physiology

• Day vision – Photopic (Cones)

• Night vision – Scotopic (Rods)

• NVG Image – mesopic (mixture)– The NVG image is fairly bright, transition to

lower light levels takes time.– Flight crews are not “dark adapted” while using

NVGs

Spatial Disorientation

• Visual Performance factors result in increased susceptibility to visual illusions– Black hole– Terrain Masking– Resolving object size/ Altitude estimation– Judging Closure rates with terrain/ aircraft

• Scanning techniques can result in disorientation

Environmental Issues

• Summer– Backlit Terrain (Terrain masking)– Dust-ball (Loss of drift cues close to ground)– Falling Rain (IIMC)

• Winter– Snow covered ground (whiteout)– Snowball (Loss of drift cues close to ground)– Falling snow (IIMC)

Environmental Issues

Cultural Lighting

• Bright light in FOV – NVG Gain decreases– Could make obstacles invisible– Halos mask obstacles– Difficulty picking obstacle lights out of

background

Environmental Issues

Remote Areas • NVG sees reflected energy – don’t work under all

conditions• NVG operating at maximum gain - scintillation

– Grainy image may mask precipitation (Inadvertent IMC)

– Lack of resolution may make obstacles impossible to see, make accurately judging closure rates impossible

Fatigue

• NVG Weight and CG – physical fatigue

• Visual performance factors – eye strain

• Increased Cognitive workload – mental fatigue

• Decreased FOV and obstructed view – physical fatigue

• Circadian Rhythms

Complacency• Complacency can be caused by excessive

fatigue• Pilot may overestimate NVG performance

– Decreased Visual Acuity – Don’t know what you can’t see

• Flying with NVG has an almost video game feel – this could lead to unconsciously taking excessive risk

Human Factors - Solutions• Pilot Training

– NVG Characteristics/Limitations– Visual Illusions– NVG Flying Skills – scanning, cross-check,

image interpretation – use of a terrain board– Minimum instrument flying training;

requirement for pilots to be instrument rated and current

• NVG Compatible Aircraft

NVIS Aircraft Integration

• Cockpit Lighting

• Aircraft Exterior Lighting

• Windshield/Window Transparency

• Physical Constraints

• Handling Qualities - AFCS

Failure Criticalities• Severe-Major/Hazardous Failures

– Display of hazardously misleading imagery

– Inadvertent/Uncommanded illumination of NVG incompatible Light

• Major Failures– Complete Loss of NVG image

– Complete Loss of NVIS Lighting System

– TSO C164, and RTCA DO 275

NVG Compatible LightingGeneral Requirements

• All sources of light in and on the aircraft must not degrade the operator’s view of the outside world through NVG.

• Interior light sources and displays must allow the pilot to easily interpret flight, navigation and system information.

• Exterior light sources must comply with CARs/FARs.

Design/Certification Issues• Prevent light leaks.• Colour integrity/intensity to meet the

certification basis, including external lights.• Daylight readability• Minimize cabin/cockpit reflections by using

appropriate paint/curtains, etc.• Continue to meet the aircraft certification

basis.

Design/Certification Issues

• Aircraft Configuration

• Maintain the qualification of all components installed or modified for NVG purposes.

• STC Applicability

• Test Conditions - Facilities

• Test Equipment

Aircraft Certification Test Program

• Ground Test– Assess windshields– Assess Interior lighting– Assess Displays

• Flight Test– Assess Exterior lighting– Confirm performance of cockpit

displays/lighting

Incompatible Cockpit Light

Poor Lighting Uniformity

Good Lighting Uniformity

Good Practice

Questions ?

Civil Approval of Aviator’s Night Vision Imaging Systems

Programs utilizing Night Vision Goggles

Background

• The development of ANVIS programs utilizing NVGs is being incorporated into, or considered by, organizations such as HEMS, police, and provincial forestry organizations.

OUTLINE

• The following slides provide guidance for Canadian approval of commercial ANVIS programs.

Definitions

• ANVIS – Aviators Night Vision Imaging System

• NVG – Night Vision Goggles

• HEMS – Helicopter Emergency Medical Services

Approval to conduct ANVIS operations will be conducted in 2 parts:

• Aircraft Certification Branch Approval

• Operational Approval

Aircraft Certification Branch Approval

• Approving the Supplement Type Certificate for installation of NVG compatible lighting in accordance with Airworthiness Notice AN BO53, and Aircraft Certification Policy Airworthiness Letter ACPL 29;

• Flight test for ANVIS compatibility; • Development of the Rotorcraft Flight Manual Supplement • Only Night Vision Goggles conforming to TSO C164 may

be used

Operational Approval • Evaluation of ANVIS ground and flight

training programs;

• Amendments to the COM including ANVIS Standard Operating Procedures (SOPs)

• Monitoring of the training program;

• Observing training and operational flights utilizing ANVIS

Additional Aircraft Equipment • A searchlight, steerable from either pilot

seat, if night landings are to be conducted anywhere other than a lit, night certified aerodrome. This light need not be NVG compatible;

• A Radar Altimeter;

• NVG compatible exterior lighting

Inspector Training

• It is recommended that Inspectors responsible for companies that wish to utilize this new technology receive training in ANVIS evaluation techniques as well as NVG operational training prior to assessing an air operator’s ANVIS program.

Company Training

• Acceptable company training programs should consist of both ground and flight training programs.

Ground Training

• Ground training should consist of classroom lectures, practical training and written exams with records of initial and recurrent training. The use of a terrain board model to simulate light levels and contrast is highly recommended. The following topics should be covered:

Ground Training• Theory of Operation;

• ANVIS Physiology and Human Factors;

• Terrain Interpretation and Environmental Factors

• SOPs and Emergency Procedures

• Pre and post flight procedures

• Flight profiles and weather considerations

Flight Training

• The aim of ANVIS training should be to “train to proficiency”. At a minimum, this training should consist of 5 separate flights of at least 1-hour duration to establish basic NVG proficiency. Previous demonstrated NVG experience; such as recent operational military NVG experience may be considered an acceptable alternative.

Flight Training

• Experience is considered current if it has occurred within the previous 24 months. During the last NVG training flight the candidate’s proficiency should be assessed in a manner similar to the pilot competency check and the candidates training file should be annotated accordingly. ANVIS flight training should include the following items:

Flight Training • Pre-flight fitting, testing, and adjustment• Rehearsal of company ANVIS SOPs • Line / route / mission indoctrination as

appropriate• Enroute procedures• Aircraft normal procedures including scanning

techniques and cockpit drills while using NVGs;

Flight Training (cont’d)

• Aircraft emergency procedures and NVG failure procedures

• Post flight removal, safe storage,and maintenance considerations.

Flight Crew Requirements

• Safe and successful ANVIS flying requires a high degree of instrument scanning proficiency.

• Pilots conducting ANVIS operations must hold a current Instrument Rating

Currency • ANVIS flying is recognised as a skill that

degrades with time and lack of currency. Company training programs must indicate minimum currency requirements to conduct ANVIS operations. The accepted interval to retain NVG currency is 90 days. After that time, a pilot may regain currency by conducting a training flight with a qualified NVG pilot prior to conducting passenger-carrying operations.

Flight Duty Time Limits• Conducting ANVIS operations, and the

wearing of NVGs increases fatigue due to increased pilot workload and by the weight of the appliance itself. Flight and duty times should be reduced for pilots conducting NVG operations.

• The current recommended maximum for ANVIS operations is 5 hours per night.

Company Operations Manual (COM) Amendments

• COMs should be amended to contain, at a minimum, the following information:

COM (Cont’d) • Comprehensive SOPs for the conduct of

ANVIS operations including normal and emergency procedures;

• Pilot NVG currency requirements

• Proficiency check requirements;

• Pilot training requirements;

• Company training pilot requirements;

COM (Cont’d)

• Crewmember training requirements and use of NVGs;

• Recordkeeping requirements;

• Minimum safe altitudes;

• Weather considerations.

Current NVG Use

• The Alberta Shock Trauma Air Rescue Society (STARS) is the first EMS operator in Canada to incorporate an ANVIS program into their operations.

• They service areas around the cities of Calgary and Edmonton and some communities in British Columbia

Type of Operation

• STARS uses their NVG program to reach communities in mountainous areas that would otherwise not be accessible due to the nighttime lateral obstacle clearance restrictions of Canadian regulations (CARs).

STARS• This is the first authority that has been granted to a

Canadian operator providing alleviation from certain Regulations while using an ANVIS program, in this case, the MOCA for night routes with respect to lateral obstacle clearance limits.

• Restrictions on the authority include; T/C approval of the ground and flight training program, pre-surveyed routes based on the use of TSO- C129 GPS units, increase in visibility on mountainous routes to 5 miles, minimum altitude enroute will be 1000 AGL.

NVG Reference Material• RTCA DO – 268 - CONOPS• RTCA DO – 275 - MOPS• RTCA DO – 295 – Training Guidelines• HBAT 02/04 - FAA Guidance• TSO C164 – Issued 30 September, 2004• FAA AC 27-1B/29-2C, MG-16 • NVG Compatible Lighting Design Requirements

– MIL-STD-3009

Summary of Key Safety Elements:

• Thorough training of flight crews in both the strengths and weakness inherent in the system.

• RADAR Altimeter.• Aircraft lighting fully NVG compatible.• Only TSO’d appliances used.• 2 pilot multi engine environment with the capability to go

IFR if required. • 1000 foot minimum ceiling and 3 mile minimum visibility

required for commercial night VFR (NVFR) ops.• 5 mile visibility required for NVFR flight in mountainous

areas

Questions ?Mike LaughlinProgram ManagerRotorcraft & Aerial WorkCommercial & Business AviationTransport Canada 613) 990-1093 Telephone / Télélephone(613) 954-1602 Fax / Télécopier(613) 297-9017 Cell / Cellulairelaughlm@tc.gc.ca