trivelloni.pdf

7/29/2019 trivelloni.pdf

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XIX AIMAS December 7th 2006

Operational Issues in

Aided Night Vision Flight

Pierandrea Trivelloni


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Night Vision DevicesNVGs vs FLIR

Night vision goggles - reflected energy Image reflective contrast

Require at least some illumination

Penetrate moisture effectively

Attenuated by smoke, haze and dust

Forward Looking InfraRed - emitted energy

Images thermal contrast

Totally independent of light

Penetrates smoke and haze

Attenuated by moisture (humidity)

B 10


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Light Sensitivity

Wavelength (nanometres)InfraredInfraredInfraredVisible LightVisible LightVisible Light

RelativeResponse(%)

HumanEye

GEN-IIINVG

100

80

60

40

20

0

400 500 600 700 800 900 1000


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Light Sensitivity

Night SkyIrradiation

Wavelength (nanometres)

RelativeResponse(%)

HumanEye

GEN-IIINVG

100

80

60

40

20

0

400 500 600 700 800 900 1000

InfraredInfraredInfraredVisible LightVisible LightVisible Light


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Image Intensification Process

PhotocathodeMicrochannel Plate

Electron MultiplierPhosphor Screen

LightLight

Secondary Electrons IndividualMultiplierTube

InputElectron

Voltage +-


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Visual Characteristicsof Night Vision Goggles

Reduced visual acuity 7/10 under ideal conditions

5/10 at best in aircraft

May be 3/10 or worse at mean starlightand/or low contrast conditions

Limited FOV - 40 degrees

Monochromatic image - no color contrast

Limits object detection and recognition


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Night Environment

High light level (HLL): > 2.2 mluxEquivalent to 20% moon disc @ 30

Best HLL: 50% moon disc @ 4080Skyglow: up to13 below the horizon


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NVGs Visual Acuity


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The Role of NVG CockpitLighting

Spatial Disorientation - MH-60

Spatial Disorientation - A/OA-10* Wire Strike - MH-60

Spatial Disorientation - A/OA-10*

Spatial Disorientation - F-16 Unknown / Mid-Air Collision - HH-60s

Brown Out / Loss of Control - MH-53

Loss of SA / Mid-Air Collision - F-16*

Misperception / Hard Landing - HH-60

Misperception / Tail Rotor Strike - MH-53

* Significant lighting deficiencies


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Mishap Primary Cause Factors leading to NVG-related CFIT mishaps

Task saturation

Breakdown of crew coordination

Poor judgment

Fatigue & Workload

Overconfidence/Complacency

Training deficiencies/Inexperience

The culminating event is

breakdown in instrument crosscheck


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Goggle Effects on Unaided FOVand Scan Patterns

NVGs are used to look outside the aircraft

Cockpit Instruments and displays (except aHUD) are viewed by looking beneath oraround the goggles

The goggle obstructs a +/- 45 degree coneof vision (40 degrees + 2.5 degreessurrounding the image)

Pilots must modify their cockpit scan toaccommodate this obstruction of vision


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The Role of NVG Cockpit Lighting

Incompatible or partially compatible lighting is aparticular hazard

The natural tendency is to turn it down in order

to reduce blooming and/or reflections However -- as a rule, an incompatible display

cannot be made compatible by turning it down

The result is a display that is less readable, orunreadable, AND still incompatible with NVGs


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Poor illumination of primary flight instrumentshas been a significant problem in NVGoperations (30% of mishaps)

It can take up to 10 seconds (515) to adapt

from a bright NVG image to a dim cockpitdisplay

Howard CM, Riegler J T, Martin J JAviation Space and Envir. J ournal: J une 2001


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Early Chromatic After-effects

Transitory

Grayish view of green and white targets

Attenuated by increasing cockpitdisplaysluminance and/or reducing the ANVISdisplay luminance

Moffitt K, Rogers SP, Cicinelli JAviation, Space and Envir. J ournal: February1988


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Early Chromatic After-effects

Transitory

Grayish view of green and white targets

Attenuated by increasing cockpitdisplaysluminance and/or reducing the ANVISdisplay luminance

Moffitt K, Rogers SP, Cicinelli JAviation, Space and Envir. J ournal: February1988


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Post-Flight Considerations Post-flight eye strain

May reflect poor pre-flight focusing Temporary depth perception problems

Due to incorrect IPD settings

Fatigue due to several factorsPhysical

Mental

Sensory


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Sensor Integration

Effective visual perception through naturaland technological sensors

Comparison between both perceptions

Increase in sensorial and mental workload Integration among several technologies

Computer generated imagery


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Fusion Imagery

Light Intensifier (NVGs)

Infra-red (FLIR)

Grey Fused (computer generated)

Color Fused (computer generated)


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Training vs Demonstration

Training implies that the trainee hasundergone a process resulting in an actualchange in behavior, performance, perceptionor response

not just informedregarding some fact orprincipal

Merely demonstrating something is NOT

training


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Next Generation Aircrew

Information management skillsSituation awareness

Spare mental capability

Team-worker


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In certain circumstancesSpatial Disorientation is

a normal physiological responseWilliam E. Berkley, Col, USAF, MC,CFS

AFRL, Mesa (AZ)

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