Town To Upgrade Weather

Photo by Andy Towle. |


The Payson Town Council recently approved spending $41,000 to get a nice, new, $250,000 all-weather guidance system at the Payson Regional Airport.

The Federal Aviation Administration will pay the bulk of the cost of overhauling the 20-year-old Automated Weather Observation System — as it has most of the improvements at the airport.

The town’s $41,000 contract with Armstrong Consulting will pay for the engineering and preparation work for installation of the system.

The FAA will pay 90 percent of the cost of the whole system, with the Arizona Department of Transportation kicking in 5 percent and Payson covering the final 5 percent.

The FAA will control the system, which reports weather conditions to a national system at 20-minute intervals. The FAA uses the information to automatically notify pilots when they’re flying into potentially dangerous weather conditions. The system reports things like wind speed and direction, temperature, dew point, visibility, sky conditions, cloud levels, lightning, thunderstorms and other conditions that affect the safety of flight.

The national network has also proved useful to the National Weather Service and to many researchers trying to get a handle on climate trends. The system used to rely on tried and true methods like weather vanes, but now increasingly come equipped with things like ultrasonic wind sensors, to measure wind speed and direction.

The system also takes sightings with a beam of xenon laser light through the air to report visibility, by measuring how much particles in the air scatter the beam. A separate laser system pointed upward measures the time it takes for scatter off the beam to bounce back from the bottoms of any overhead clouds, so it can generate a warning to pilots when cloud cover might make for dangerous landing conditions.

The system also uses infrared beams to measure rain and snowfall, although most still can’t detect hail and ice pellets — which leaves a significant gap from a pilot’s point of view.

The temperature sensors use the a device

that measures the electrical resistance in a platinum wire, which changes with the temperature. Measuring the dew point presents a much more complicated problem. Many systems use a chilled mirror cooled to the point that moisture in the air condenses on the surface. A laser system measures the water vapor on the surface, yielded the calculation as to the temperature at which water will condense out of the air given the humidity.

Other sensors include a vibrating rod whose resonant frequency changes depending on the presence of ice or snow and a lightning detection system that records any lightning strikes within about 10 miles.

The whole system works automatically and constantly reports the measurement to a national system, which issues updates to pilots all over the country.

The decision represents the first major upgrade to the airport since Payson resumed its management from the previously independent Payson Regional Airport Authority. The council resumed control back in December, after struggling for several years to work through the legal complexities of having the town own the airport and assume legal responsibility for all FAA grants and having an independent volunteer group of airport users actually manage the facility.

The council reappointed most of the Airport Board members to a new town-administered airport board, but the move simplified the process of applying for the FAA grants on which the airport has relied for almost all of its improvements.

The town also hopes to accelerate progress in implementing an ambitious airport master plan, which would over the next 20 years roughly double landings and provide various support facilities, including a terminal, more hangars and the construction of airport-related businesses in the area.


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