As pilots, we rely on weather reports to decide whether to fly—or not. Yet not all weather reports are equal. While most aviation surface observations are generated by a machine, in some cases humans still confirm or correct the observations–making them more trustworthy than totally automated reports. Recently proposed changes by the National Weather Service (NWS) to reduce their role in collecting weather data will lessen the quality of these reports at some of our weather stations in Alaska—with fewer stations being “augmented” by a human to provide a more complete and representative weather report. This is a concern both for the reports that pilots use to make those critical go-no go decisions, and possibly for the quality of the forecasts that we rely on to anticipate changing conditions while inflight.
What is augmented weather?
Today most aviation weather reports (METARS) are generated by a machine, either an Automated Weather Observing System (AWOS) or Automated Surface Observing System (ASOS) depending on who owns it. These machines operate 24 hours a day, and can generate “specials” when weather conditions are changing, but have limitations that have been recognized since they first became operational. For example, even though the beam of light that measures cloud height is more precise than a human just looking out the window, the extent of a cloud layer isn’t known until enough of it has drifted across the sensor to allow a computer to determine if the sky condition is FEW, SCATTERED, BROKEN or OVERCAST. It also doesn’t alert the pilot to the fog layer that has been approaching the station for several hours, and is about to make an airport go IFR. Visibility is another case where very local conditions can trick the system. The estimate of visibility is computed from the number of particles that break a one meter beam of light. It can be fooled by local disturbances such as a patch of fog, or exhaust from a vehicle. And it can’t report the reduction in visibility as a weather system approaches until it envelopes the station. For a pilot on a cross country flight—this may be too late!
If there were enough weather reporting stations distributed over the landscape, they would tend to fill in the gaps, and provide a good spatial picture of the weather. But with the large size of Alaska, and general lack of infrastructure, we are woefully short of reporting stations. Even in the “lower 48” the limitations of automated stations are recognized, and the US has adopted a system of service levels so that the larger, more heavily used airports have human observers who double check the automated stations. In these locations, trained weather observers augment the reports to overcome system limitations, and can back them up when components of the system fail. Here again, Alaska loses out, as our traffic counts often don’t qualify for augmentation services. Fortunately, the FAA recognized this when they consolidated Flight Service Stations in the 1990s. In response to push-back from the aviation community, they kept either a part-time Flight Service Station, a contract weather observer, or in some cases NWS staff at locations formerly served by a Flight Service Station to perform the augmentation task. Today, we are being advised that the NWS is shifting the responsibility for this function to the FAA, and withdrawing this service at eleven locations across the state, which is the current source of concern.
Which stations are augmented?
There are several entities that can augment weather reports. Flight Service Station staff are trained to make weather observations, and may augment them. Tower controllers and NWS weather staff in some locations also perform augmentation, as well as contracted weather observers. Some stations are augmented 24 hours a day, while others only during hours when an FAA facility is open—either daily or seasonally. To see a list of stations and times, see the Alaska Augmentation Sites.pdf file. For a more visual form, see the map below.
What is the change?
Recently the NWS came out with a public notice indicating that the responsibility for aviation weather augmentation and back-up is transitioning to the FAA. The NWS plans to discontinue augmentation at eleven stations across the state. In some cases, this would merely reduce the hours the observation is augmented. In four locations augmentation would be eliminated entirely—Yakutat, Saint Paul, Kodiak and Annette Island. McGrath would have no augmentation from October through April. Reductions in augmentation would be seen in an additional six locations, including Nome, Kotzebue, King Salmon, Cold Bay, Bethel, and Barrow. The FAA has already suspended the contract weather observer at Gulkana, which is another former Flight Service Station location, and regional hub in the Copper River Basin. AOPA has asked to have the Gulkana observer re-instated, given its importance as a regional cross-roads in the Copper River Valley.
Who cares about augmentation?
I hope all pilots consider whether the METAR they are evaluating is augmented or not. Especially when conditions are changing, one should be wary of unattended, automated sites. If the METAR is augmented, you can place greater reliance on its being accurate, and to capture hints of change, which are often recorded in the REMARKS section. While IFR-capable operators can generally handle more weather than VFR pilots, even they are subject to minimums and need decent alternates in their hip-pockets. As primarily a VFR pilot, I am always looking closely at the reports available, to see that I will continue to have a suitable place to deviate, if needed. Remember, the term AUTO in a raw METAR means that the station is NOT being augmented!
Trends and the future of aviation weather reports
Zooming out to the bigger picture, this proposed change is yet another reduction in weather information available to pilots. In the past few years, we have seen A-Paid observers eliminated, leaving holes in the weather picture, vital for cross country flights to remote parts of Alaska. We continue to have weather-related accidents, and now the quality and quantity of reports from some of the automated weather stations are eroding. AOPA has written a letter to the NWS and FAA challenging this recent proposed change, and asking that, at a minimum, a safety risk analysis be conducted, with aviation community input, prior to reducing these services. We also want to see a comprehensive review of the overall weather reporting system needed to support aviation in Alaska.
Stay tuned for further developments!