TBL GEN 3.5.2
Product Update Interval Transmission Interval Service Domain and Look-ahead Range (NM)
AIRMET As Available 5 minutes 100 (Airport Surface), 500 (Terminal, Enroute/ GOMEX)
SIGMET & Convective SIGMET As Available, then at 15 minute intervals for 1 hour 5 minutes 100 (Airport Surface), 500 (Terminal, Enroute/ GOMEX)
METAR/SPECI 1 minute (where avail-able), As Available other-wise 5 minute 100 (Airport Surface), 500 (Terminal, Enroute/ GOMEX)
NEXRAD Composite Reflectivity (National) ~5 minutes precipitation mode 10 minutes for clear air mode 15 minutes CONUS
NEXRAD Composite Reflectivity (Regional) ~5 minutes precipitation mode 10 minutes for clear air mode 2.5 minutes 250
NOTAM (D) / FDC (including TFR) As Available 10 minutes 100
PIREP As Available 10 minutes N/A (Airport Surface), 500 (Terminal, Enroute/ GOMEX)
SUA As Available 10 minutes N/A (Airport Surface), 500 (Terminal, Enroute/ GOMEX)
TAF/AMEND 8 Hours 10 minutes 100 (Airport Surface), 500 (Terminal, Enroute/ GOMEX)
Winds & Temperatures Aloft 12 Hours 10 minutes 1,000
7.5.1.1 The products should be either FAA/NWS “accepted” aviation weather reports or products, or based on FAA/NWS accepted aviation weather reports or products. If products are used which do not meet this criteria, they should be so identified. The operator must determine the applicability of such products to their particular flight operations.
7.5.1.2 In the case of a weather product which is the result of the application of a process which alters the form, function or content of the base FAA/NWS accepted weather product(s), that process, and any limitations to the application of the resultant product, should be described in the vendor’s user guidance material.
7.5.2
An example would be a NEXRAD radar composite/mosaic map, which has been modified by changing the scaling resolution. The methodology of assigning reflectivity values to the resultant image components should be described in the vendor’s guidance material to ensure that the user can accurately interpret the displayed data.
8.
Weather Observing Programs
8.1 Manual Observations. Aviation Routine Weather Reports (METAR) are taken at more than 600 locations in the U.S. With only a few exceptions, these stations are located at airport sites and most are staffed by FAA or NWS personnel who manually observe, perform calculations, and enter the observation into the distribution system. The format and coding of these observations are contained in FIG GEN 3.5.24.
8.2 Automated Weather Observing System (AWOS)
8.2.1 Automated weather reporting systems are increasingly being installed at airports. These systems consist of various sensors, a processor, a computer.generated voice subsystem, and a trans-mitter to broadcast local, minute.by.minute weather data directly to the pilot.
NOTE.
When the barometric pressure exceeds 31.00 inches Hg., see Section ENR 1.7, Altimeter Setting Procedures.
8.2.2 The AWOS observations will include the prefix “AUTO” to indicate that the data are derived from an automated system. Some AWOS locations will be augmented by certified observers who will provide weather and obstruction to vision informa-tion in the remarks of the report when the reported visibility is less than 3 miles. These sites, along with the hours of augmentation, are published in the Airport/Facility Directory. Augmentation is identi-fied in the observation as “OBSERVER WEATH-ER.” The AWOS wind speed, direction and gusts, temperature, dew point, and altimeter setting are exactly the same as for manual observations. The AWOS will also report density altitude when it exceeds the field elevation by more than 1,000 feet. The reported visibility is derived from a sensor near the touchdown of the primary instrument runway. The visibility sensor output is converted to a visibility value using a 10.minute harmonic average. The reported sky condition/ceiling is derived from the ceilometer located next to the visibility sensor. The AWOS algorithm integrates the last 30 minutes of ceilometer data to derive cloud layers and heights. This output may also differ from the observer sky condition in that the AWOS is totally dependent upon the cloud advection over the sensor site.
8.2.3 Referred to as AWOS, these real.time systems are operationally classified into nine basic levels:
8.2.3.1 AWOS.A only reports altimeter setting.
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