Rotary Wing
Night Flight
Part I
Wings of Freedom
Reference
FM 3-04.203
Wings of Freedom
Contents
I. Night Vision
II. Hemispherical Illumination and Meteorological
Conditions
Wings of Freedom
I. Night VisionA. Combat Visual Impairments
1. Night Laser Hazard•
Eye is more vulnerable at night, iris of eye opens more
to accommodate lower levels of illumination
•
Laser damage to eyes includes flash blindness, retinal
burns, impaired night vision
•
Normal cockpit tasks, obstacle avoidance, use of
acquisition/targeting systems become difficult or
impossible
Wings of Freedom
I. Night Vision
A. Combat Visual Impairments
2. Nerve Agents•
Exposure of the eyes to nerve agents adversely
affects night vision
•
Contact with nerve agents result in miosis
(constriction of the pupils)
•
Repeated exposure is cumulative
•
Severe miosis can last for approximately 48 hours
and full recovery may take up to 20 days.
Wings of Freedom
I. Night Vision
B. Aircraft Design Limitations and
Solutions
1. Design Eye Point (DEP)•
Point where crew station designer specifies where
aircrew member’s eyes should be
•
Allows aircrew member to acquire information
easily and quickly
•
Proper seat position required to achieve DEP.
Aircrew member should be able to see ground
approximately 12 feet in front of nose of aircraft.
Wings of Freedom
I. Night Vision
B. Aircraft Design Limitations and
Solutions
2. Aircrew Coordination•
Safest and most effective solution to overcoming
design limitations.
•
Requires interaction, communication, and actions
between all crewmembers.
3. Additional crewmembers•
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Assist aircrew members by providing information
on hazards, obstacles, and unintentional drift or
movement.
I. Night Vision
B. Aircraft Design Limitations and Solutions
4. Lighting•
Minimizing lighting without hindering reading of
essential instruments allows maximum visibility
outside the aircraft
•
Balance tactical needs with need to comply with
Federal Aviation Regulations (FARs) and local
policies
Wings of Freedom
II. Hemispherical Illumination and
Meteorological Conditions
A. Light Sources
1. Lunar Light•
Moon Angle changes about 15 degrees per hour
(1 degree/4 minutes)
•
Light is brightest at highest point or zenith
•
There are four distinct phases of lunar light and
illumination
Wings of Freedom
II. Hemispherical Illumination and
Meteorological Conditions
A. Light Sources
1. Lunar Light-Phases of Lunar Light Cycle
a)
New Moon-
•
•
Last approximately 8 days
Moonlight increases towards end of phase when
approximately 50% of moon is illuminated
b)
First Quarter-
•
•
•
Last approximately 7 days
Begins when moon is approximately 50% illuminated
Ends when slightly less than 100% of moon is illuminated
Wings of Freedom
II. Hemispherical Illumination and
Meteorological Conditions
A. Light Sources
1. Lunar Light-Phases of Lunar Light Cycle
(cont)c)
Full Moon-
•
•
Begins when 100% of disk is illuminated
Ends 7 days later when 50% of disk is visible
d)
Third Quarter-
•
•
•
Last approximately 7 days
Begins when about 50% of moon is visible
Ends when 2% or less is visible
Wings of Freedom
II. Hemispherical Illumination and
Meteorological Conditions
A. Light Sources
2. Solar Light•
Unusable when sun is 12 degrees below horizon
(48 minutes after sunset) This is End Evening
Nautical Twilight (EENT)
•
Becomes usable when sun is 12 degrees below
horizon (48 minutes before sunrise) This is
Beginning Morning Nautical Twilight (BMNT)
•
End Evening Civil Twilight and Beginning Morning
Civil Twilight (EECT/BMCT) occur when sun is 6
degrees below horizon.
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II. Hemispherical Illumination and
Meteorological Conditions
A. Light Sources
3. Other Sources of Illuminationa)
Starlight•
Provide some background lighting
•
b)
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Provide about 1/10th the illumination of a quarter
moon
Artificial Light
•
Lights from cities, automobiles, fires and flares
provide small amounts of illumination
•
Artificial light is most pronounced during overcast
conditions
II. Hemispherical Illumination and
Meteorological Conditions
B. Other Considerations1. Meteorological Effects
•
•
•
Predicting light levels not always accurate
Adverse Weather difficult to detect at night
Decrease in visual acuity and loss of horizon can be very
subtle
2. Clouds•
•
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Reduce hemispherical illumination depending on amount
of absorption/reflection
Aircrew members should monitor ambient light and cloud
coverage to determine if conditions are deteriorating.
II. Hemispherical Illumination and
Meteorological Conditions
B. Other Considerations
3. Restrictions to Visibility•
Loss of Celestial Lights- Overcast clouds may
cause moon and stars to fade and/or disappear
•
Loss of Ground Lights- City or rural lights fade
due to obscuration
•
Reduced Ambient Light Levels- Obscurations will
reduce forecast light levels
Wings of Freedom
II. Hemispherical Illumination and Meteorological
Conditions
B. Other Considerations3. Restrictions to Visibility (cont)•
Reduced Visual Acuity- Best-Case visual acuity is based on high
ambient night illumination, high contrast, and clear visibility.
•
Best resolution with aviator’s night vision imaging system
(ANVIS) occurs somewhere between 25 to 50 percent moon
illumination
•
Light levels above 50 percent moon illumination do not improve
ANVIS resolution
•
Scintillation- Low ambient light levels increase video noise and is
seen as a sparkling effect by crewmembers.
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II. Hemispherical Illumination and
Meteorological Conditions
B. Other Considerations4. Lightning•
Creates the same effect as a flare
•
Intensity depends on proximity of the flash and
strength of the storm
•
Night vision may be temporarily impaired if the
aircrew is too close to lightning activity
Wings of Freedom
QUESTIONS?
Wings of Freedom