Reporting Visibility
As you determine visibility, also assess whether the conditions are uniform, or whether they are fluctuating, increasing, or decreasing. Visibility values are typically reported in nautical miles, with increments provided in Table II-4-1 of your observer's manual. When the prevailing visibility is estimated to be more than the distance to the farthest visibility marker, estimate the visibility to the nearest reportable value up to 10 nm.
| Nautical Miles | Nautical Miles |
|---|---|
| 0 | 3 |
| 1/16 | 4 |
| 1/8 | 5 |
| 1/4 | 6 |
| 1/2 | 7 |
| 1 | 8 |
| 1 1/2 | 9 |
| 2 | 10 |
| 2 1/2 |
If the visibility is halfway or less between two reportable values, enter the lower value. If the visibility is more than halfway between two reportable values, enter the higher value (e.g., 6 3/4 mile visibility is rounded up to 7 miles).
If the visibility is less than 3 miles and variable during the time period of observation, report the average of all observed values, adding on a V and enter the range of visibility in the Remarks section, e.g. VIS 1V3.