Definition
A continuous broadcast of recorded hazardous weather information transmitted over selected VOR (VHF Omnidirectional Range) navigation frequencies. The broadcast contains summaries of current weather hazards such as severe weather warnings, SIGMETs, Convective SIGMETs, AIRMETs, urgent pilot reports, and Center Weather Advisories affecting the airspace within roughly 150 nautical miles of the broadcasting station.
Plain English
A non-stop weather warning broadcast pilots can listen to over certain navigation radio stations while flying. It tells them about dangerous weather happening in their area without them needing to call anyone.
Context Anchor
Seen on older en route chart legends and navigation aid boxes, including low altitude instrument charts.
Derivation
The name is built directly from its function: a service that issues advisories about hazardous weather while pilots are inflight. No deeper origin needed — the acronym describes exactly what it does.
Why Pilots Care
Provides immediate access to critical hazard information without requiring the pilot to leave the frequency or contact flight service, supporting safer route and altitude decisions.
Analogy
Think of it like a local emergency weather radio station, but tuned through the same navigation radio the pilot is already using to fly.
Intuition Check
HIWAS was not a personal weather briefing or a clearance. It was a one-way broadcast of hazardous weather information for pilots to listen to in flight.
Example Sentence 1
While cruising at 8,000 feet, the pilot tuned the nearby VOR and listened to the HIWAS broadcast for any thunderstorm advisories along the route.
Example Sentence 2
While en route the pilot switched to the local VOR frequency to listen for any HIWAS updates on developing thunderstorms ahead.