Page 71 - AFMAN 15-111, 12 MAR 2019

AFMAN15-111 12 MARCH 2019 71

13.5.6.1. FBWOS and JET software compute DA using different formulas; the formula
used by JET takes into account water vapor and the FBWOS does not. AF weather
organizations should provide their supported units with DA values obtained directly from
the ADS and TMQ-53 sensor displays when available. (T-3).

13.5.6.2. When the primary pressure sensor is inoperative, notify ATC agencies that the
reported PA and DA values are estimated.
13.5.7. Rapid Pressure Changes. The FBWOS/JET automatically enter this remark if the
condition is detected. If unavailable, manually determine whether the pressure change at the
time of an observation and report the condition in the remarks of the observation using the
format in Attachment 3.

13.6. Comparison and Calibration Procedures. Each unit with an AN/TMQ-53, a hand-held
barometer, and/or equivalent will establish a barometer comparison/calibration program. (T-3).
Note: Comparisons should be delayed during periods of high wind speeds (25 knots or higher,
sustained or gusting), rapid temperature changes or steep horizontal and/or vertical temperature
gradients (i.e. frontal system in area or frontal passage).
13.6.1. Record and document barometer comparisons on a locally developed
worksheet/spreadsheet, or MAJCOM or higher headquarters approved
form/worksheet/spreadsheet. Retain the last two barometer comparisons on file and dispose of
all others.

13.6.2. Deployable barometers (e.g., AN/TMQ-53, handheld barometer).
13.6.2.1. At a minimum, compare barometers against a standard barometer annually,
before deployment, when first deployed, if relocated during a deployment, and as soon as
practical after redeployment.
13.6.2.2. Determine a mean correction by making at least four comparisons, not less than
15 minutes apart, against the standard barometer.
13.6.2.2.1. For handheld barometers, the standard barometer is the local observing
system (i.e., AN/FMQ-19, AN/FMQ-23, or AN/TMQ-53).

13.6.2.2.2. For the AN/TMQ-53, the standard barometer can be either the local
observing system or, when available, a maintenance standard barometer (used by
airfield systems/depot maintenance personnel).
13.6.2.3. Apply the mean correction (or adjust the software to reflect the correction) to a
fifth pressure reading. If the corrected reading differs from the standard barometer by more
than 0.01iHg (0.34hPa), re-accomplish the steps above. If the corrected reading exceeds
0.03iHg (1.01hPa), discontinue use and replace the device (for the AN/TMQ-53, turn in to
depot maintenance).