12 - Visibility of Lights Flashcards
Types of lights
- Primary seacoast lights
- Sector lights
- Range lights
Four standard light colors for lighted NAVAIDS
- Green
- Red
- White
- Yellow
Fixed Period
Continuously on (rarely on due to power consumption)
Flashing period
When the on time is less than the off time
Occulting period
When the on time is more than the off time
Isophase period
Equal on and off times
Group flashing (or occulting) period
Lights that flash or occult in regularly occuring patterns by periods of continuous light or darkness
Frequency of flashes
- Flashing lights
- < 30 flashes per minute
- Quick flashing lights
- 50 - 80 flashes per minute
- Very quick flashing lights
- > 80 flashes per minute
Height Of Eye (HOE)
Required for determining geographical range
Nominal Range
Required for determining light’s luminous range.
Computed visibility
Distance at which you can actually see the light
- Must determine luminous and geographical range and compare lesser of the two is the range at which you should first sight the light.
Meteorlogical Visibility
Atmospheric conditions have a marked effect on the luminous range of lights
Luminous Range
Limiting range at which the light is visible under prevailing atmospheric conditions and disregarding limitations caused by its heights and the Earth’s curvature.
Visible Range
Visible range of a light based upon the heights of the light and the observer (without considering the meteorlogical conditions).
Range Lights
Pair of fixed markers, often lighted, that are positioned some distance apart in a channel.
Primary Seacoast lights
Sector lights
Light characteristics
