Table of Contents:
l. Definition
2. Purpose
4. Procedures
4.l Acquisition
4.2 Dissemination
4.2.1 Urgent PIREP's
4.2.2 Individual PIREP's
4.2.3 Local PIREP's
5. NMC Computer Collection of PIREP's
5.l Identification of UB's
5.2 Example of UBUSl Bulletin
5.3 Use of Request/Reply (R/R) for PIREP's
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l. Definition. PIREP's are reports of meteorological phenomena encountered by aircraft in flight.
2. Purpose. In-flight reports from pilots (PIREP's) serve a threefold purpose in the National Aviation System (NAS). They are a primary source of information for other pilots of weather conditions in between surface weather reporting points; they provide input to the air traffic control system enabling more expeditious routing of aircraft; and they provide valuable input to the National Weather Service (NWS) aviation forecast program. In order to achieve these purposes, PIREP's must be entered into the system as quickly as possible and delivered to the users without delay. Close cooperation between NWS and the Federal Aviation Administration (FAA) personnel is required to assure the efficiency of this program.
3. Responsibility. PIREP's are generated by pilots who may report on air-ground radio to an FAA facility, or provide a post-flight report of conditions to either an FAA Flight Service Station (FSS) or Weather Service Office (WSO). The Federal Aviation Regulations require only that a pilot report conditions which he believes would be hazardous to another aircraft; otherwise, the reporting of in-flight weather conditions is voluntary. Hence, it is incumbent on the pilot weather briefers (both NWS and FSS) to encourage pilots to report whenever they encounter weather conditions different from what they had expected. Experience has demonstrated that pilots will cooperate in reporting when they can be convinced that use is made of the information they report. NWS Headquarters will maintain its activity to stimu1ate the PIRFP's program through its national organization contacts. However, the success of the program will still be largely dependent on the pilot weather. briefers at field offices both in the acquisition and dissemination of PIREP's.
4.1 Acquisition. Any NWS facility may request PIREP's from its affiliated FSS whenever such reports are deemed beneficial to pilot weather briefing or the production of forecasts and/or warnings. This provision is made in the FAA Handbook 7110.10A, Flight Services, Chapter 4, Section 3, Paragraph 1258 (and following). Requirements are also placed on FSS's (see Airman's Information Manual, Part 1, Chapter 5, pp. 1-81) to solicit and collect PIREP's under certain weather conditions. Additionally, FAA Handbook 7110.9C, En Route Air Traffic Control, Chapter 2 Paragraphs 80 and 81, establish procedures for the solicitation and relay of PIREP's when requested by a WSFO. EWAS facilities are also in a unique position to acquire pilot reports, as indicate1 in WSOM Chapter D-28.
Since the rea1 focal point for handling PIREP's is the FSS, WSO's and WSFO's should coordinate with the local FSS to assure that PIREP's will be available. If there is no FSS in the local area, coordinate with the local Air Traffic Control Tower (ATCT) or Air Route Traffic Control Center (ARTCC). If there is no FAA faci1ity on the airport, coordination with the nearest FSS is recommended, and assistance in arranging such coordination may be obtained through the appropriate QCO.
NWS facilities such as the National Meteorological Center (NMC), the National Hurricane Center (NHC), and the National Severe Storms Forecast Center (NSSFC), may have special requirements for PIREP's on a seasonal or other basis. Coordination of these requests can most effectively be handled through the affiliated WSFO utilizing the established FSS communications facilities. If additional broader coordination is required, such as on a national 1eve1, Aviation Branch, W116, at NWS Headquarters, should be contacted for making arrangements.
4.2 Dissemination. PIREP's are extremely perishable and therefore need to be distributed as promptly as the system will permit in order to be effective. Procedures for distribution are given in the fo11Owing references:
a. Federal Meteorological Handbook (FMH) #1, Chapter A-11. This reference contains instructions for encoding PIREP's for transmission.
b. FAA Handbook 7110.10B, Part II, Chapter 5, Section 5, (plus changes and GENOT's). This reference contains instructions for proper transmission procedures.
4.2.1 Urgent PIREP's. Pilot reports concerning tornadoes, funnelclouds, or waterspouts are considered to be of an urgent nature, and arrangements have been made through the assignment of a special heading (reference paragraph 4.2.b, above) which has priority over any transmission in progress on the MWTCS.
4.2.2 Individual PIREP's. Pilot reports concerning hail, turbulence, icing or other potentially hazardous phenomena not as severe as those listed in paragraph 4.2.1 are assigned a heading which assures priority transmission without interrupting a transmission in progress.
4.2.3 Local PIREP's. Pilot reports concerning ceilings, cloud bases and tops, visibilities (slant and aloft) or weather in the local area are included in the remarks section of the transmitted surface weather report.
5. NMC Computer Collection of PIREP's. At the National Meteorological Center (NMC) at Suitland, Maryland, pilot reports are collected each hour from Service A area circuits. These are blocked into nine bulletins, each for an FA area in the conterminous 48 states and headed UBUSl. Each of the nine bulletins is subdivided by states within the FA area utilizing a north-south orientation and alphabetized by call letters within each state in accordance with the example in paragraph 5.1 below. The WSFO's preparing FA's are San Francisco, Salt Lake City, Kansas City, Ft. Worth, New Orleans, Chicago, Washington, Boston, and Miami.
5.1 Identification of UA's. Since the NMC computer program on UBUSl's recognizes pilot reports identified by UA on Service A messages, pilot reports appended to hourly observations require this UA identifier also, preceding the pilot report. Examples of UA's appended to observations are as follows:
/UA 1730 ZONE HTS MDT TURB 180 B727
/UA 1421 20NE MLU LGT ICG 120 BE 36
/UA 1245 0/FL0 40 BE 36
Further detailed instructions on the format of UA's can be found in Federal Meteorological Handbook No. 1, Surface Observations, with changes and OML W1421 dated October 25, 1972. Only recognized station identifiers are used as found in FAA Handbook 7350.1.
5.2 Example of UBUSl Bulletin. UBUSl (Pilot Report Summaries) bulletins will be prepared by NMC two times per hour at H + 25 and H + 45 and transmitted to the Weather Message Switching Center (WMSC) at Kansas City via the high-speed line. WMSC will then transmit the individual bulletins on the dedicated lines to the respective FA centers two times per hour:
UBUSl KBOS DTG
ME UA 241900
PWM UA 1905 TEXT
NH UA 241900
NO RPRTS AVBL
VT UA 241900
NO RPRTS AVBL
MASS UA 241900
BOS UA 1915 TEXT
BOS UA 1927 TEXT
ORH UA 1850 TEXT
5.3 Use of Request/Reply (R/R) for PIREP's.
a. UBUS1 bulletins can be obtained by using R/R and the message format RC, e.g., RC UBUS1 KDCA. The bulletins obtained in this manner will contain up to two hours worth of PIREP's.
WSOM Issuance
73-1 1-23-73