Section 4. Hazardous Inflight Weather Advisory Service (HIWAS)
- Hazardous Inflight Weather Advisory Service (HIWAS), available in the 48 contiguous states and the District of Columbia, is a continuous broadcast of inflight weather advisories including AWWs, WSs, WSTs, CWAs, WAs, and UUAs.
- HIWAS broadcast areas are defined as the area within 150 NM of a HIWAS outlet.
HIWAS broadcasts must not be interrupted/delayed except for emergency situations, when an aircraft requires immediate attention, or for reasonable use of the voice override capability on specific HIWAS outlets in order to use the limited Remote Communication Outlet (RCO) to maintain en route communications. The service must be provided 24 hours a day.
- Make the following announcement if there are no hazardous weather advisories in the HIWAS broadcast area. Update the announcement at least every 2 hours.
THIS RECORDING PREPARED AT (time) ZULU. THERE ARE NO HAZARDOUS WEATHER ADVISORIES WITHIN A ONE-FIVE-ZERO NAUTICAL MILE RADIUS OF THIS HIWAS OUTLET.
- Complete the update recording as soon as practical, but not more than 15 minutes from time of receipt of new hazardous weather information.
Record hazardous weather information occurring within the HIWAS broadcast area. The broadcast must include the following elements:
- Statement of introduction including the appropriate area(s) and a recording time.
HIWAS WITHIN A ONE-FIVE-ZERO NAUTICAL MILE RADIUS OF (geographic area) RECORDED AT (time) ZULU (text).
Border facilities must append “in domestic U.S. airspace” to the geographical area text in the introduction statement.
- Statement of hazardous weather, including WSTs, WSs, WAs, UUAs, AWWs, and CWAs.
- Request for PIREPs, if applicable. (See Paragraph 9-2-5, Soliciting PIREPs.)
PILOT WEATHER REPORTS ARE REQUESTED.
- Recommendation to contact Flight Service for additional details concerning hazardous weather.
CONTACT FLIGHT SERVICE FOR ADDITIONAL DETAILS.
- BROADCAST PROCEDURES
- Upon receipt of new hazardous weather information:
- Update the HIWAS broadcast.
- Make a HIWAS update announcement once on all communications/navigational aid (NAVAID) frequencies except on emergency and navigational frequencies already dedicated to continuous broadcast services.
ATTENTION ALL AIRCRAFT, HAZARDOUS WEATHER ADVISORY UPDATE FOR (geographical area) IS AVAILABLE ON HIWAS, OR CONTACT FLIGHT SERVICE, as appropriate.
- In the event that a HIWAS broadcast area is out of service, make the following announcement on all communications/NAVAID frequencies except on emergency and navigational frequencies already dedicated to continuous broadcast services:
ATTENTION ALL AIRCRAFT, HAZARDOUS WEATHER ADVISORY UPDATE IS AVAILABLE FROM FLIGHT SERVICE.
Simultaneous announcements may cause heterodyne problems on multiple outlets having the same frequency and interference over close outlets with known problems. Announcements may have to be rebroadcast to insure compliance.
HIWAS broadcasts must not be suspended for routine maintenance during periods when weather advisories have been issued for the HIWAS outlet area.