Page 15 - AFMAN 15-111, 12 MAR 2019

AFMAN15-111 12 MARCH 2019 15

3.7. Magnetic Declination. The local magnetic declination must be determined at each
observing location to convert wind direction from magnetic to true. (T-1). Obtain local magnetic
declination from the installation’s DoD FLIPs or the Tactical Plotting Chart for your area,
whichever is most current, or the National Oceanographic and Atmospheric Administration
National Centers for Environmental Information website located at
http://www.ngdc.noaa.gov/geomag-web/#declination. Local declination changes by several
minutes of arc each year at most locations. Weather leadership must monitor FLIPs or revised
charts for changes in local magnetic declination. (T-1). Shifts in declination may affect the
orientation of the wind equipment; therefore, keep maintenance personnel informed of changes.

3.7.1. From magnetic to true: add easterly declination to magnetic direction and subtract
westerly declination from magnetic direction.

3.7.2. From true to magnetic: add westerly declination to true direction and subtract easterly
declination from true direction.
3.8. Unofficial Weather Reports. Unofficial weather reports are defined as a report of one or
more weather elements from an individual who is not task certified to take official weather
observations (e.g., a pilot or law enforcement official). Unofficial reports can provide additional
and supplemental information that may be important to local aviation and public safety. They can
also help increase the WF’s/Det’s situational awareness. Unofficial reports of severe weather from
credible sources within 15 SM will be reported in the remarks section of the observation IAW
Attachment 3 and disseminated longline and locally during augmentation of an FBWOS. (T-2).
As the “eyes-forward,” WFs/Dets follow up credible reports of severe weather with the supporting
OWS.
3.9. Modes of Observation. For meteorological observations the ‘point of observation’ is
defined as the designated spot where the elements of an observation are viewed and/or sensed. The
point of observation is within 5 SM (8000 m) of the airfield and affords as clear a view as possible
of the runway complex. If necessary as an exception, the point of observation may be located
further than 5 SM from the airfield but will be documented in the weather support plan and FLIP.
(T-2).
3.9.1. Automated observations. The point of observation is the location(s) of the primary
sensor group and the discontinuity sensor group. If the primary sensor group or the
discontinuity sensor group is moved or a site survey shows the reported location information
to be in error, the updated latitude, longitude, and elevation are provided in the station
information file.

3.9.2. Augmented/Manual observations. The point(s) of observation will be the location of the
primary and discontinuity (when available) sensor group(s) for objective elements and the
designated point of observation used by WF/Det personnel to evaluate subjective elements and
back-up sensed objective elements as needed. (T-2).
3.10. Rounding of Figures and Values. Except where otherwise directed in this AFMAN,
round figures and values to the nearest reportable value (standard algebraic rounding). Example:
1.5 becomes 2, -1.5 becomes -2, 1.3 becomes 1, and -1.4 becomes -1.