12/21/2012 JO 7900.5C Table of Contents Chapter 1. Introduction ..........................................................................................................................1 1.1. Purpose of This Order. .............................................................................................................. 1 1.2. Audience. .................................................................................................................................. 1 1.3. Where to Find This Order. ........................................................................................................ 1 1.4. Cancellation. ............................................................................................................................. 1 1.5. Explanation Of Changes. .......................................................................................................... 1 1.6. Abbreviations and Acronyms. .................................................................................................. 2 1.7. Relationship to FMH-1 and Other Documents ........................................................................... 2 1.8. Applicability of Procedures and Practices .................................................................................. 2 1.9. User Responsibilities. ............................................................................................................... 3 1.10. Distribution. ............................................................................................................................. 3 1.11. Changing the Order. .................................................................................................................. 3 1.12. Maintaining the Order. .............................................................................................................. 3 Chapter 2. Guidelines ............................................................................................................................4 2.1. Introduction. ................................................................................................................................ 4 2.2. Types of Stations......................................................................................................................... 4 2.3. General Types of Observations ................................................................................................. 5 2.4. Augmentation Requirements. ..................................................................................................... 5 2.5. Backup Requirements ................................................................................................................. 6 2.6. Long-Line Backup Requirements ............................................................................................. 10 2.7. Certification of Personnel and Currency Requirements.. ......................................................... 11 2.8. Types and Content of METAR/SPECI Observations. ............................................................ 12 Chapter 3. General Procedures ............................................................................................................13 3.1. Introduction. ............................................................................................................................ 13 3.2. Definitions................................................................................................................................. 13 3.3. Aviation Weather Observing Locations. ................................................................................. 14 3.4. General Observing Practices. .................................................................................................. 15 3.5. Dissemination. ....................................................................................................................... 16 3.6. Dissemination Requirements. ................................................................................................. 16 3.7. Corrections to Transmitted Data. ............................................................................................ 17 3.8. Delayed Reports. ..................................................................................................................... 17 3.9. Rounding Off Numbers. .......................................................................................................... 17 3.10. Record Keeping and Forms ...................................................................................................... 17 3.11. Evaluating Weather Sensor Accuracy ...................................................................................... 17 3.12. Criteria for SPECI Observations. ............................................................................................ 18 3.13. Content of METAR/SPECI Observations. ............................................................................. 19 Chapter 4. General Procedures at Automated Weather Stations .........................................................28 4.1. Purpose. ................................................................................................................................... 28 4.2. Types of Automated Stations .................................................................................................... 28 4.3. Certification. ........................................................................................................................... 30 4.4. General Procedures. ................................................................................................................ 30 4.5. General Equipment Procedures. .............................................................................................. 30 4.6. Procedures at Non-Federal Observation Sites. See Appendix B. ............................................ 31 4.7. Procedures at Non-Federal AWOS Sites. ............................................................................... 31 ii 12/21/2012 JO 7900.5C 4.8. Procedures for Handling Aircraft Mishaps at Automated Sites. ............................................. 31 4.9. General Requirements for Record Keeping. .......................................................................... 31 Chapter 5. Augmentation Requirements at Automated Weather Stations ..........................................32 5.1. Introduction. ........................................................................................................................... 32 5.2. Validity of Data. ...................................................................................................................... 32 5.3. Sign On/Sign Off the Automated Weather Observing Systems. ............................................ 32 5.4. Order for Reporting Weather and Obstructions to Visibility. ................................................. 33 5.5. Augmentation Observing Procedures. .................................................................................... 34 5.6. Reporting Procedures ................................................................................................................ 34 5.7. Examples of Augmented Observations. .................................................................................. 36 Chapter 6. Backup Requirements at Automated Weather Stations .....................................................37 6.1. Introduction. ........................................................................................................................... 37 6.2. Summary of Backup Requirements. ....................................................................................... 37 6.3. Validity of Data. ...................................................................................................................... 38 6.4. Equipment Requirements. ...................................................................................................... 38 6.5. Procedures for Providing Backup Information. ..................................................................... 39 6.6. Coding of Missing Data. ......................................................................................................... 39 6.7. Procedures for Wind Speed and Wind Direction. ................................................................... 39 6.8. Procedures for Visibility. ........................................................................................................ 41 6.9. Procedures for Present Weather and Obscurations. .................................................................. 42 6.10. Procedures for Sky Condition. ................................................................................................ 43 6.11. Procedures for Temperature and Dew Point. .......................................................................... 46 6.12. Procedures for Altimeter Setting. ........................................................................................... 47 6.13. Procedures for Documentation. ............................................................................................. 47 6.14. Procedures for Communications. ........................................................................................... 47 6.15. Disposition of MFIM-10C. ..................................................................................................... 47 6.16. Examples of Backup Observations. ......................................................................................