Visibility Flashcards
At what height should visibility be observed from the ground?
1.5m
Describe prevailing visibility
The greatest visibility that is reached within at least 1/2 of the horizon circle or within at least 1/2 of the surface of the aerodrome in contiguous or non-contiguous sectors.
Describe minimum visibility
When the visibility in one direction is less than 1500m or 50% less than the prevailing visibility, this should be reported as minimum visibility after the prevailing visibility, including a designator for the compass direction it relates to.
What do you do if the minimum visibility is in more than one direction?
Report the most operationally significant
What do you do if the visibility is fluctuating rapidly and no prevailing visibility can be determined?
Only the lowest visibility should be reported, with no indication of direction.
Do you report a minimum visibility that is greater than or equal to 10km?
No. 9999 is the largest visbility to be reported.
Can you report 9999 and a minimum visibility?
Yes. So long as the minimum visibility is less than 10km and at least 50% less than the prevailing visibility.
What are the rounding rules for visibility reporting?
Visibility should be rounded DOWN to:
• The nearest 1000m between 10km and 5km
• The nearest 100m between 5km and 800m
• The nearest 50m below 800m
How is a visibility of 40m encoded?
- Any visibility less than 50m is coded thus.
How is a visibility of 12km encoded?
- Any visibility greater than 10km is coded thus.
Name the weather hazards and atmospheric conditions that can affect visibility.
- Fog
- Mist
- Low Cloud
- Precipitation (rain/drizzle/snow/hail etc)
- Spray
- Dust
What needs to accompany a visibility of less than 5000m.
A present weather code to explain the obscuration.
What is the name of the equipment that automatically detects visibility?
Visiometer
Can visibility just be promulgated as reported by the visiometer?
No, a manual estimation of visibility must always be obtained also.
When looking at a reference point, how do you judge if the visibility is about the same or greater than the distance to the reference point?
- If the object is visible with sharp outlines and little blurring of colour, the visibility is much greater than the distance to it.
- If the object can barely be seen and identified and there is little colour, the visibility is about the same as the distance to it.
