Accident report: Gaining insight

From the terminology used in air traffic control communications, such as approach clearances, to some components of the system itself, changes that emerged from examining the lessons of significant accidents have helped keep aircraft and their occupants safer today.

Take weather information. In today’s flight environment, most pilots have a wide variety of choices for how to benefit from the plenitude of real-time information available for keeping tabs on weather along a route of flight.

Although HIWAS has gone away, its essential mission of making hazardous weather information readily available endures.So much has digital information delivery transformed pilots’ choices for accessing weather information that a service long in use, the well-known HIWAS service (for hazardous inflight weather advisory service) transmitted over some navaids, was discontinued in January 2020. Suppose you were flying at low altitude in a remote area with spotty radio coverage but near a VOR. All you had to do was turn up the volume and listen (over the Morse code identifier) to a continuous HIWAS broadcast to become aware of any bad weather moving in. This came in handy when flying low-altitude wildlife surveys on the lee side of interior Maine’s mountains, where a speedy squall line could sneak up unseen on an unwary flier.

Although HIWAS has gone away, its essential mission of making hazardous weather information readily available, born of a 1980 accident involving an airliner and a thunderstorm, endures.

On June 12, 1980, an Air Wisconsin Swearingen SA–226 Metro, a twin turboprop, crashed in the vicinity of Valley, Nebraska, killing 13 of 15 occupants. While flying at less than 6,000 feet in an area with severe thunderstorms, both the aircraft’s engines failed as a result of “massive water ingestion,” according to the official accident report.

After investigating, the NTSB noted “numerous deficiencies” in air traffic control’s acquisition and dissemination of weather data—both to controllers and pilots. A complicating factor was that rain-induced attenuation had likely affected the ability of the aircraft’s radar to detect the storms’ severe echoes, but the pilots probably were unaware of that problem, the NTSB said.

When providing comments to the FAA on ways to smoothly transition from HIWAS to NextGen-era weather services, AOPA pointed out the continuing importance of making information on hazardous weather available to pilots, citing the safety recommendation the NTSB made after the 1980 crash that urged that “significant meteorological information be transmitted over navigation aids” to pilots who at that time “had few alternatives for inflight status updates.” The FAA adopted HIWAS systemwide in 1988.

Since July 2018, all weather products that were once provided over HIWAS are now available via the free Flight Information Service-Broadcast (FIS-B), which leverages ADS-B technology, except for the Alert Severe Weather Watch Bulletin—which is similar to the FIS-B-provided convective sigmet.

To this day, however, not every pilot is digitally equipped. To keep the safety mission of HIWAS fully functioning, the FAA also agreed that flight service specialists will remain available to provide information on hazardous inflight weather by radio. And air traffic controllers will continue to advise pilots of hazardous weather within 150 nautical miles of the ATC sector area in which they are flying.

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