Section 9. Weather/Visibility

1. BACKUP/AUGMENTATION OF WEATHER OBSERVATIONS

1. Facilities where air traffic personnel provide backup/augmentation of automated weather observations, or take manual observations, must use FAA Order 7900.5, Surface Weather Observing-METAR, as the basic source of guidance for completion of observations.
2. In an automated weather environment, elements of automated weather observations may be used for operational purposes (i.e., wind and altimeter).
3. Specialists responsible for providing backup/augmentation of automated weather observations, or manual observations, must be certified by the FAA.

1. RECEIPT AND DISSEMINATION OF WEATHER OBSERVATIONS

1. Facility 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.
2. 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.
3. The 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:

1. An aviation requirement exists.
2. The observers are/have been certified by the FAA.
3. No other observation exists in the surface area, if applicable.
4. Identifies the hours that the data will be available if less than 24 hours, i.e., 0800Z-2300Z.
5. Identify what facility will be responsible for observation entry into the system.

1. AWOS towers with LAWRS certified controllers should disable the AWOS long-line communications capability during facility operating hours and use the AWOS data when representative of airport conditions to generate a manual 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.

1. LIMITED AVIATION WEATHER REPORTING STATION (LAWRS) HOURS OF OPERATION

1. Facility air 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.
2. All part-time terminal facilities must include sign ON/OFF procedures for the automated weather observation system in the facility opening/closing procedures.

1. All LAWRS facilities must ensure the automated weather observation system equipment is added to the facility watch checklist.

1. NONAVIATION WEATHER SERVICE

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 nonaviation weather activity. Refer requests for this type of weather information to the nearest WSO.

1. 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.

1. VISIBILITY CHARTS

1. Air Traffic Managers at facilities that provide backup/augmentation of automated weather observations, manual observations, and/or tower visibility observations, must select a designee to prepare and maintain visibility charts as follows:

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 used.
2. Daytime/Nighttime combination charts must use the following legend for each marker:
   
3. Each 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 charts.

1. The air traffic manager must conduct an annual review and approve the visibility charts, lists, or photos to ensure their accuracy.

1. SITING 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:

1. The most frequently used instrument runway and its final approach area; and
2. At least half of each quadrant of the natural horizon.

1. RUNWAY VISUAL RANGE (RVR) EQUIPMENT

1. FAA is responsible for checking and determining the operational status of RVR systems. Air traffic personnel must report all actual or suspect RVR malfunctions to Technical Operations Control Center personnel who are responsible for:

1. All checks and adjustments to the RVR systems.
2. Determining the operational usability of all portions of the systems in accordance with applicable performance criteria in FAA Order JO 6560.8, Maintenance of Runway Visual Range (RVR) Equipment, or other appropriate RVR equipment instruction books.
3. Reporting immediately to authorized visibility observing personnel obvious error between information derived from the system and actual observed visibility conditions at the transmissometer site.

1. Air traffic personnel must also:

1. Verify 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 information.
2. Notify 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 RVR values for that runway. During such conditions, weather observing personnel will relay RVR information to tower personnel as long as equipment at the weather observing facility is known to be operating correctly and 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 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 to or exceed:

1. RVR 2,400 feet.
2. The lowest authorized landing minimum for the runway of concern.

1. SPECIFIC AREA MESSAGE ENCODING (SAME) WEATHER RADIOS

TERMINAL

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.

1. SAME Radios must not be used in lieu of pre-existing emergency evacuation procedures or FAA certified sources of aviation related weather data.
2. SAME Radios must only be programmed for the specific county/territory of the facility.
3. 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.”