Chapter 10 — WATCH ROUTINES 



Miscellaneous Coded Data 



Data for the 850-, 700-, and 500-mb standard 

 isobaric surfaces, low level mean winds, and 

 the stability index are required by the National 

 Meteorological Center and the Forecast Centers 

 as soon as possible after the beginning of the 

 ascent. Therefore, as soon as these data are 

 obtained they are coded in a separate message 

 for early distribution in accord with current 

 communications instructions. 



The data reported by means of the Early 

 Transmission Message are additional to that 

 reported for the 850-, 700-, and 500-mb stand- 

 ard surfaces included in the complete radio- 

 sonde report, and in no way affect the coding 

 procedures specified for the preparation of that 

 report. In other words, data for the 850-, 700-, 

 and 500-mb surfaces are included in their usual 

 places in the complete radiosonde report. Sta- 

 bility index is included only in the Early Trans- 

 mission Message, and it is not included in the 

 complete radiosonde report. Procedures for en- 

 coding can be found in FMH No. 4, Radiosonde 

 Code. 



All raob stations that file hourly aviation 

 observations on longline teletypewriter circuits 

 are required to append freezing level and icing 

 data in the remarks portion of the first hourly 

 observation following determination of the data. 

 Procedures for coding and transmitting this 

 data may be found In FMH No. 1, Surface 

 Observations. 



Pilot Reports 



Pilot reports of meteorological phenomena 

 encountered in flight are termed PIREPS. These 

 reports are an extremely valuable source of 

 information that often is not otherwise avail- 

 able. Weather observers should cooperate to 

 the fullest extent possible with pilots and flight 

 operation personnel to secure and disseminate 

 this information. PIREPS are recorded on 

 MF1-12. 



4. SK — Cloud information (bases, tops). 



5. TA — Temperature (static air tempera- 

 ture). 



6. WV — Wind information (airborne com- 

 puter derived spot wind direction and speed). 



7. TB — Turbulence (intensity, altitude or 

 layer) . 



8. IC — Aircraft icing (intensity, altitude or 

 layer). 



9. WX — Weather (all types and leg wind 

 components) . 



Each TEI, except for message type, will 

 be preceded by a slash (/). If no data are 

 received for a specific TEI, it will be omitted 

 and all of the remaining data moved to the 

 left. 



RECCO Code 



Weather reconnaissance, the collection of 

 meteorological data by aircraft, is an important 

 tool in providing forecasts for areas where data 

 is sparse or nonexistent. 



The code name RECCO is used as a pre- 

 fix to the report, indicating that it is a report 

 from a meteorological reconnaissance flight. 



Present weather, cloud type and amounts, 

 turbulence, and surface data are reported for 

 a cylindrical portion of the atmosphere approxi- 

 mately 30 nautical miles in radius with the air- 

 craft at the center at the time of the 

 observation. The length of this cylinder extends 

 from the earth's surface to the top of the 

 atmosphere. Weather beyond the circumference 

 of the observation cylinder is reported as off 

 course weather. 



The solidus (/) is used to report missing 

 or unknown data unless otherwise specified for 

 the individual elements. 



CODING FOR DISSEMINATION. — The format 

 for dissem' nation of PIREPS consists of a 

 unique Text Element Identifier (TEI) as follows: 



1. UA — Message type. 



2. OV — Location of phenomena (location, 

 time, flight level). 



3. TP — Type of aircraft. 



The term " altitude" as used in this code, 

 is defined as the vertical distance of a level 

 point or an object considered as a point meas- 

 ured from mean sea level in metric units ex- 

 clusively. 



Plain language remarks may be added to the 

 end of the report to supplement the coded data 



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