Section 9. Weather/Visibility
2-9-1. BACKUP/AUGMENTATION OF WEATHER OBSERVATIONS
where air traffic personnel provide backup/augmentation of automated
weather observations, or take manual observations, must use FAAO 7900.5,
Surface Weather Observing-METAR, as the basic source of guidance for
completion of observations.
b. In an
automated weather environment, elements of automated weather observations
may be used for operational purposes (i.e., wind and altimeter).
responsible for providing backup/augmentation of automated weather
observations, or manual observations, must be certified by the National
Weather Service (NWS).
FAAO JO 7210.3, Para 14-1-2, Certificates of Authority.
2-9-2. RECEIPT AND
DISSEMINATION OF WEATHER OBSERVATIONS
air traffic managers must establish a means by which the receipt of
weather observations are immediately known to facility personnel
responsible for dissemination to other facility functions and that these
functions are made aware of changes as they are posted. In addition,
facility managers must establish procedures through the facility SOP that
will ensure all positions of operation receive and acknowledge any change
in reportable visibility value when the tower has the responsibility for
visibility reporting. This may be accomplished by means of an alerting
device, location of weather receiving equipment at positions so that any
change of data is recognized, or any other means which may be best suited
to the facility work environment.
b. To the
extent possible, facility air traffic managers must establish procedures
to acknowledge receipt of weather observations. Where possible, establish
an agreement with the appropriate weather source to share the
responsibility for ensuring the receipt of the observation. Automated
Surface Observing System(s) (ASOS), Automated Weather Observing System(s)
(AWOS), and Automatic Weather Information System (AWIS) locations are not
required to acknowledge receipt of observations.
addition or deletion of a weather reporting location must be coordinated
through the appropriate Service Area office, for forwarding to System
Safety and Procedures. System Safety and Procedures must initiate the
required actions for additions and/or deletions to the national data base.
When adding new weather reporting locations, include a statement that:
aviation requirement exists.
observers are/have been certified by the NWS.
3. No other
observation exists in the surface area, if applicable.
the hours that the data will be available if less than 24 hours, i.e.,
what facility will be responsible for observation entry into the system.
towers with LAWRS certified controllers should use the AWOS operator
interface device (OID) to generate a manual hourly METAR/SPECI
observation. If AWOS is able to provide METAR/SPECI observations (for
example, FAA AWOS-C) and allows augmentation and backup entries, the AWOS
may be used the same as ASOS/Automated Weather Sensor System (AWSS).
AVIATION WEATHER REPORTING STATION (LAWRS) HOURS OF OPERATION
traffic mangers must submit to System Operations Airspace and Aeronautical
Information Management office the hours of operation with the date that
the facility commences participation in the LAWRS program and any changes
thereafter in the hours of participation.
Facilities must not
enter into agreements with any person or office, including fixed-base
operators, to provide weather data for property protection purposes. The
FAA must not be responsible for providing weather information unless it is
directly related to the actual or intended operation of aircraft.
Personnel must not encourage nor solicit non-aviation weather activity.
Refer requests for this type of weather information to the nearest WSO.
2-9-5. NATIONAL WEATHER RECORDS CENTER
Refer requests for
surface weather observations from non-aviation sources; e.g., requests
from insurance companies for weather data relative to storm damage, to the
National Weather Records Center, Environmental Data Service, Federal
Building, Asheville, N.C., 28801.
Where facilities provide backup/augmentation of
automated weather observations, or manual observations, the facility air
traffic manager will select a designee that will prepare and maintain
visibility charts in accordance with the following:
1. Prepare a
chart(s) or list(s) for daytime and nighttime visibility markers. At local
discretion, visibility markers may be depicted on separate daytime and
nighttime charts or on a daytime/nighttime combination chart. Panoramic
photographs marked with distances and cardinal compass points may also be
combination charts must use the following legend for each marker:
marker used must be identified and its distance from the observation point
noted. Include the height of the marker if it is for estimating heights of
clouds and obscuring phenomena.
4. Mapping programs, aircraft/vehicles, GPS
and/or surveying equipment are all valid methods to develop visibility
b. The air traffic manager must conduct an annual
review and approve the visibility charts, lists, or photos to ensure
CRITERIA FOR VISUAL WEATHER OBSERVATIONS
To give a proper
indication of weather conditions in the areas of aircraft approaches,
landings, and takeoffs, the site from which visual weather observations
are made should ideally be the Airport Reference Point (ARP). If this is
not practical, the site must be as close to the ARP as practical. Except
in unusual circumstances, it should be no more than 2 miles from that
point. The site must also have an essentially unobstructed view of:
a. The most
frequently used instrument runway and its final approach area; and
b. At least
half of each quadrant of the natural horizon.
VISUAL VALUE (RVV) AND RUNWAY VISUAL RANGE (RVR) EQUIPMENT
a. FAA is
responsible for checking and determining the operational status of RVV/RVR
systems. Air traffic personnel must report all actual or suspect RVV/RVR
malfunctions to Technical Operations Control Center personnel who are
checks and adjustments to the RVV/RVR systems.
the operational usability of all portions of the systems in accordance
with applicable performance criteria in FAAO JO 6560.8, Maintenance of
Runway Visual Range (RVR) Equipment, or other appropriate RVR equipment
immediately to authorized visibility observing personnel obvious error
between information derived from the system and actual observed visibility
conditions at the transmissometer site.
Technical Operations personnel are not visibility observers. However,
obvious errors or differences which are easily apparent to them will be
reported to the visibility observer and the instrument-derived information
should not be used.
traffic personnel must also:
accuracy with other displays in the facility when any meter and/or readout
malfunction is suspected. Upon determining that at least one display is
operating properly, accomplish internal coordination to disseminate the
current correct reading to all operating positions needing the
the local weather observing facility immediately when malfunctioning of
all airport traffic control tower (ATCT) and terminal radar approach
control (TRACON) displays for the runway of concern is indicated or
suspected. Upon verification of malfunction, request the weather observing
facility to furnish RVV or RVR values for that runway. During such
conditions, weather observing personnel will relay RVV or RVR information
to tower personnel as long as equipment at the weather observing facility
is known to be operating correctly and, in the case of RVR, when the high
intensity runway lights (HIRL) are on setting 3 or higher. RVR values
provided during the malfunction will be based on a setting of 5 unless the
control tower has specifically requested data for a lower light setting.
The weather observing facility will provide the RVR or RVV at the time of
notification that the traffic control facility readouts are inoperative.
It will also provide notification as soon as possible when the values
decrease to become equal to or less than, or increase to equal or exceed:
(a) RVV 1/2 mile or RVR 2,400 feet.
lowest authorized landing minimum for the runway of concern.
AREA MESSAGE ENCODING (SAME) WEATHER RADIOS
SAME Radios must
only be used to provide weather information for occupants of Terminal
facilities. This equipment is not certified for the purpose of providing
weather or any other aviation-related information and therefore must not
be used for any aviation-related purpose.
Radios must not be used in lieu of pre-existing emergency evacuation
procedures or FAA certified sources of aviation related weather data.
Radios must only be programmed for the specific county/territory of the
following must be affixed to the SAME Weather Radio so as to be visible:
“This equipment is not certified for the purpose of providing weather or
any other aviation-related information and therefore must not be used for
any aviation-related purpose.”