8/15/19 3/15/07 1/30/20 AIM  7110.65R CHG 2 AIM e. TBL 7 − 1 − 3 contains a comparison of weather observing programs and the elements reported. f. Service Standards. During 1995, a govern- ment/industry team worked to comprehensively reassess the requirements for surface observations at the nation’s airports. That work resulted in agreement on a set of service standards, and the FAA and NWS ASOS sites to which the standards would apply. The term “Service Standards” refers to the level of detail in weather observation. The service standards consist of four different levels of service (A, B, C, and D) as described below. Specific observational elements included in each service level are listed in TBL 7 − 1 − 4. 1. Service Level D  defines the minimum acceptable level of service. It is a completely automated service in which the ASOS/AWOS observation will constitute the entire observation, i.e., no additional weather information is added by a human observer. This service is referred to as a stand alone D site. 2. Service Level C  is a service in which the human observer, usually an air traffic controller, augments or adds information to the automated observation. Service Level C also includes backup of ASOS/AWOS elements in the event of an ASOS/ AWOS malfunction or an unrepresentative ASOS/AWOS report. In backup, the human observer 4. Service Level A , the highest and most demanding category, includes all the data reported in Service Standard B, plus additional requirements as specified. Service Level A covers major aviation hubs and/or high volume traffic airports with average or worse weather. 3. Service Level B  is a service in which weather observations consist of all elements provided under Service Level C, plus augmentation of additional data beyond the capability of the ASOS/AWOS. This category of airports includes smaller hubs or special airports in other ways that have worse than average bad weather operations for thunderstorms and/or freezing/frozen precipitation, and/or that are remote airports. Two categories of airports require detail beyond Service Level C in order to enhance air traffic control efficiency and increase system capacity. Services at these airports are typically provided by contract weather observers, NWS observers, and, at some locations, FSS observers. inserts the correct or missing value for the automated ASOS/AWOS elements. This service is provided by air traffic controllers under the Limited Aviation Weather Reporting Station (LAWRS) process, FSS and NWS observers, and, at selected sites, Non − Federal Observation Program observers. Meteorology 7 − 1 − 30 Element Reported Wind Visibility Temperature Dew Point Altimeter Density  Altimeter Cloud/Ceiling Precipitation Identification Thunderstorm/ Lightning Precipitation Occurrence Rainfall Accumulation Runway Surface Condition Freezing Rain Occurrence Remarks Type ASOS X X X X X X X X X X AWOS − A X AWOS − A/V X X AWOS − 1 X X X X AWOS − 2 X X X X X AWOS − 3 X X X X X X AWOS − 3P X X X X X X X AWOS − 3T X X X X X X X AWOS − 3P/T X X X X X X X X AWOS − 4 X X X X X X X X X X X X Manual X X X X X X X REFERENCE −  FAA Order JO 7900.5, Surface Weather Observing, for element reporting. TBL 7 − 1 − 3 Weather Observing Programs