This chapter prescribes procedures and practices to be followed by personnel responsible for manually observing, reporting and/or transmitting surface weather information required for augmentation, and/or for sustaining minimum operations in the event of partial or total failure of the automated weather observing system. This chapter also describes specific differences in these procedures and practices applicable to LAWRS observers.

4-2.   DEFINITIONS

a.  Observer. The generic term "observer" applies to a number of different types of personnel with various responsibilities for providing weather information. These various types are:

(1)  Weather Observer. A person who is certified by the NWS to provide a designated range of weather observation elements. These include NWS, NWS-contract, FAA and FAA-contract personnel.

(a)  LAWRS Observer. An NWS-certified air traffic control specialist (ATCS) with weather observation responsibilities for surface aviation weather elements.

(b)  Tower Visibility Observer. An ATCS certified by NWS to observe and report airport visibility from the control tower.

(2)  A-Paid Observer. Contract weather observers who take only hourly observations (METAR). They are certified by NWS to provide weather information under the terms of a "per-observation" agreement.

(3)  NF-OBS Observer. A non-federal observer working under the guidelines of the NF-OBS program, providing backup and augmentation of the ASOS.

b.  Surface Weather Observing Stations

(1)  Automated Station. A facility with an automated weather observing system that prepares the observation for transmission with no certified observer signed on to the system.

(a)  Augmentation. The manual addition of data to an automated observation which is beyond the capabilities of the automated weather observing system.

(b)  Backup. An alternative method of providing the weather observation when any portion of the automated observation is unavailable or erroneous due to sensor/system malfunction, communications failure and/or non-representative data.

(2)  Manual Station. A facility where certified weather observers are responsible for observing, evaluating, and processing the surface aviation observation. At these facilities, various types of automated weather observing systems, sensors and/or other automated equipment may be available.

(3)  NF-OBS Program. A program whereby a local entity such as a non-federal control tower (NFCT), airport personnel or fixed-based operator (FBO) may assist, at no cost to the Government, with the augmentation or backup of the automated weather observing system. Observers must be certified by NWS.

4-3.   TYPES OF AUTOMATED STATIONS

a.  FAA, FAA-contract and NF-OBS Stations. There are two major classes of automated surface weather observing systems used at FAA, FAA-contract and NF-OBS sites: ASOS and AWOS. The augmentation and backup of these systems are described in the next two chapters for all FAA, FAA-contract and NF-OBS site personnel.

(1)  Automated Surface Observing System (ASOS). ASOS is a type of automated surface weather observing system developed through a joint FAA/NWS/DOD agreement. FAA ASOSs are installed at designated airports and maintained by the NWS to meet FAA requirements. There are three configurations of ASOS. The first contains at least one of each of the following sensors:

(a)  Wind sensor.

(b)  Visibility sensor.

(c)  Precipitation identification sensor.

(d)  Cloud height indicator sensor.

(e)  Temperature and dew point sensors.

(f)  Pressure sensors.

(g)  Precipitation accumulation sensor.

(2)  The second ASOS configuration has a freezing precipitation sensor in addition to all of the above sensors. The third configuration has a thunderstorm/lightning sensor. Systems without individual lightning sensors will get thunderstorm reporting via the Automated Lightning Detection and Reporting System (ALDARS). Many sites have an ASOS/ATIS Interface Unit (AAIU), which provides the capability to broadcast current weather from the ASOS over the ATIS ground-to-air radio when the tower is closed. ASOS may also have an interface to New Generation RVR equipment. See Chapter 10, Runway Visual Range.

(3)  Automated Weather Observing System (AWOS). AWOS is a type of automated surface weather observing system certified and commissioned by the FAA. The AWOS was developed under a Flight Standards Service-sponsored project specifically to provide weather information at locations without previous weather observation capabilities. There are eight types of AWOS, namely, A, 1, 2, 3, 3P, 3T, 3P/T, and 4.

(a)  AWOS-A: AWOS-A contains only dual-pressure sensors that measure pressure and report altimeter setting to the pilot.

(b)  AWOS-1: AWOS-1 contains the AWOS-A sensors plus sensors to measure wind data (speed, direction, and gusts), temperature, and dew point, and to report density altitude.

(c)  AWOS-2: AWOS-2 contains all the AWOS-1 sensors, plus a visibility sensor.

(d)  AWOS-3: AWOS-3 contains all the AWOS-2 sensors, plus a cloud height sensor.

(e)  AWOS-3P: AWOS-3P contains all the AWOS-3 sensors, plus a precipitation identification sensor.

(f)  AWOS-3T: AWOS-3T contains all the AWOS-3 sensors, plus a thunderstorm/lightning reporting capability.

(g)  AWOS-3P/T: AWOS-3P/T contains all the AWOS-3 sensors plus a precipitation identification sensor and a thunderstorm/lightning reporting capability.

(h)  AWOS-4: AWOS-4 contains all the AWOS-3 sensors, plus precipitation occurrence, type and accumulation; freezing rain; thunderstorm; and runway surface condition sensors.

(4)  Many AWOSs were installed at airports without previous weather observations, so personnel may not be available to augment or back up the automated weather observations. The most common type of AWOS observation is the AWOS-3. It is identified by AUTO (automated report) in the body of the report and AO1 (automated station without precipitation discriminator) in the remarks section if it is a fully automated report. If it is being augmented/
backed up by an observer, it will not have AUTO in the body of the report and it will have AO1 in the remarks section. (See examples in Figure 5-2, Examples of Augmented Observations.)

b.  Non-FAA Stations. In addition to the systems described above, there are various NWS, DOD and non-federal automated weather observing systems. All non-federal automated weather observing systems to be used for aviation must be certified and commissioned by the FAA in accordance with the most current version of FAA Advisory Circular AC 150/5220-16, Automated Weather Observing Systems (AWOS) for Non-Federal Applications.

4-4.   CERTIFICATION

All FAA and contract personnel, including LAWRS personnel, responsible for providing weather observations, augmentation information, tower visibility observations or backup weather information shall be certified at least to the level commensurate with current duties. Certification shall be in accordance with the provisions of paragraph 2-7, Certification of Personnel.

At automated weather observing locations, the specified weather information shall be taken, recorded and disseminated in accordance with the procedures and practices in this order. Operator procedures for recording and disseminating augmentation and backup information are summarized in Figure 4-1, Operator Procedures for Providing Augmentation and Backup Information. Weather information taken and reported should reflect only those conditions seen, or reported by a reliable source, from the usual point of observation and, unless otherwise specified, must have occurred at the time of the observation.

General equipment operating instructions to perform the duties associated with automated weather observing systems are contained in the following publications:

a.  For all federal and non-federal AWOS systems manufactured by Qualimetrics, Inc., the AWOS Operator Instructions.

b.  For non-federal AWOS systems manufactured by AAI/SMI, Inc.; Vaisala Inc., Handar Business Unit; the appropriate AWOS user manual as approved by the FAA.

c.  For ASOS, the ASOS Software User’s Manual or Ready Reference Guide.

d.  For future automated weather observing systems as may be approved by the FAA, the appropriate operations manual or quick reference guide.

Upon request from a non-federal entity, a written agreement to provide augmentation and backup of the ASOS at a commissioned ASOS site will be executed between the Regional Air Traffic Division and the NF-OBS provider. The agreement shall be site-specific and shall contain the hours and the service level at which service will be provided. The minimum level of augmentation shall be the FAA-validated aviation service standard level for that site. Service may be provided at a higher level, however the NF-OBS provider must provide that higher level during all hours of operation. As Service Level D is a stand alone ASOS site, NF-OBS providers operating at these sites shall provide a minimum of level C service.

4-8.   PROCEDURES AT NON-FEDERAL AWOS SITES

FAA facilities shall negotiate a letter of agreement (LOA) with the airport management or appropriate authority at locations where a non-federal AWOS is installed at an airport with an operating control tower. The LOA shall define responsibilities, equipment and coordination requirements, identify special operating conditions, and define local requirements. ATCSs may disseminate only those non-federal weather observations that are obtained through the weather message switching center or other equivalent documented means. Pilots who want non-federal AWOS information from sites that do not include automatic long-line dissemination should be provided the appropriate frequency and/or telephone number, if known.

4-9.   PROCEDURES FOR HANDLING AIRCRAFT MISHAPS AT AUTOMATED SITES

The requirement to record the present weather following an aircraft mishap remains valid at automated sites. At a minimum, a mishap requires weather data from 1 hour before to 1 hour after the mishap occurs. ASOS observations should be archived by the observer or by calling the ASOS Operations and Monitoring Center (AOMC) (1-800-242-8194). The AOMC has the capability to archive the 5-minute observations from the previous 12 hours of weather observation data from attended and unattended locations. The supervisor or controller-in-charge shall ensure that the 5-minute observations are archived following notification of an aircraft mishap at a location where an ASOS is operational. AOMC requests must be made within 10 hours of the incident. Archive AWOS data in accordance with the procedures in the AWOS Operator Instructions or by calling the AWOS Central Monitoring Center at 1-800-322-0433 or 801-320-2184.

Automated weather observation data and operator terminal entries are archived on site. No further action is required by FAA, FAA-contract or NF-OBS facilities. If the automated weather observing system is completely inoperative, follow the record-keeping procedures for manual stations.

4-11. - 4-12. RESERVED