AI airport weather stations may yet proliferate

At 800 feet in the climb, Wartofsky was unable to establish radio contact with air traffic control. He circled in IMC, just outside the approach for what was known then as Washington National Airport,  troubleshooting his radio. He could have legally proceeded NORDO to his destination, “But there's no way I'm going to fly IFR at night from Washington over New York into Boston with no radio,” he recalled.

That same year, he attempted a night landing in gusty winds at Lee Airport in Annapolis, Maryland, which doesn’t have an automated weather observing system, so pilots must use weather from Bay Bridge Airport, 11 nautical miles to the east and across the Chesapeake Bay; Tipton Airport, 12 nm northeast; or Baltimore/Washington International Thurgood Marshall Airport, 15 miles due north.

On that night, those three airports were reporting contradictory winds. Wartofsky found himself in the dark, having to find the poorly lit windsock—flying a twin, at traffic pattern altitude and airspeed—and determine which runway was his best option. It made him wonder, “Why doesn’t Lee Airport have its own AWOS system? And how can I prevent having to make perilous approaches into small airports that don’t?”

Those incidents spurred Wartofsky to invent MicroTower. It’s a technology with all of the functionality of an AWOS-3 system, with artificial intelligence added to enable voice communication with pilots over unicom. The system can issue crosswind or wind shear verbal warnings and respond to radio check requests. MicroTower is solar powered, with battery backup and the option to connect to utility power. It is pole-mounted and requires less than 50 square feet of clear space to set up. At roughly $100,000 to purchase and install, it is also far less expensive for small airports and hospitals to acquire and maintain than an FAA-certified AWOS that typically costs about $650,000 to install and requires annual maintenance from approved technicians that costs tens of thousands of dollars more.

Yet nearly half of the 200 MicroTower units purchased to date have been installed overseas. Wartofsky still hopes to change that.

MicroTowers in the United States, like the others, report information online via satellite telemetry, though pilots must use nongovernment websites to view the data.

Pilots use microphone clicks from their VHF radio to initiate local communication with the AI-enabled device. Bob Kraven, a Great Lakes pilot based at Potomac Airfield, finds the microphone-activated weather and radio check features essential.

“Before I’m ready to taxi, four clicks of the mic, I do a radio check,” Kraven said. MicroTower responds with “five by five” or “two by zero,” as the case may be. Three clicks trigger a weather report.

“Because of the AI layer, it gives recommendations like, ‘Preferred no-wind runway is Zero Six,’ or ‘Caution, crosswind, caution, wind shear.’ And it knows if there are airplanes in the pattern, so it will advise if aircraft are landing on one runway or are using crossing runways,” Kraven said.

The web-based remote access allowing pilots to check current airport weather from home justified the initial cost of installation at Bolivar Municipal Airport in Missouri. Said Kerrick Tweedy, airport manager and CEO of the FBO Service Oriented Aviation Readiness , “We have pilots who drive in from 30 [to] 45 miles away. The way weather patterns move through, they got frustrated driving up here to find out that they couldn’t go fly.”

Bolivar’s master plan had long included an AWOS system, but that project never got off the ground, primarily because Bolivar is landlocked. That plan called for an AWOS to be installed on the edge of the property, but the airport didn't have enough land. A traditional AWOS requires about 18 acres of cleared land.

“We were either going to have to buy land or navigate easements from nine people next to the airport,” said Tweedy. Then Bolivar lost its Airport Improvement Plan funds. Unable to fund an expensive AWOS system, Tweedy reached out to Wartofsky about a MicroTower installation. “David gave me references in South Dakota.”

Those references included Bruce Lindholm, former program manager for the South Dakota Department of Transportation. Lindholm initially ordered 20 MicroTowers.

“Those were installed at small airports in rural communities where you maybe have five or ten aircraft on the field,” Lindholm said, “but three of them are crop sprayers, which are a really important part of that community.”

Other MicroTowers were installed at Native American tribal airports to accommodate daily medevac operations at tribal medical facilities. All are airfields where the initial cost of an AWOS-3 system and its ongoing maintenance were too high a barrier to overcome.

An AWOS-3 system averages over $650,000 just to install. Additionally, FAA-required, quarterly AWOS system checks by a specialized, FAA-approved technician cost between $40,000-$75,000 annually. Failure to comply will result in the FAA decommissioning the AWOS.

Tweedy found funding to install Bolivar’s MicroTower unit for less than $100,000, its average cost.

“Once delivered, we set the thing up in an afternoon. We intended to get it hooked up to power but never did. It's just sitting there running on solar,” he said. The MicroTower runs on batteries on overcast days and at night. It was installed six years ago and remains fully operational.

South Dakota went on to purchase an additional nine MicroTower units, bringing the total installed to 29.

Wartofsky is no stranger to improving technology systems. While a teenage intern at the Massachusetts Institute of Technology computer science center, he made a major breakthrough in how pacemakers store electrocardiogram information. At age 20, Wartofsky left Princeton University to found Bionet Medical, a medical research and diagnostic technology company. By 1995, less than two years after his close calls, Wartofsky had established Potomac Aviation Technology Corp. and produced his first MicroTower.

Back in the late 1990s, the FAA decided to rapidly roll out NextGen satellite navigation approach procedures, especially at small general aviation airfields. The move was intended to give airports lacking land-based instrument approach equipment the ability to provide satellite-based instrument approaches to pilots. GPS approaches made rural airports not just more accessible, but also safer.

In line with the new policy, the FAA approved MicroTower in 1998 to deliver certified weather, altimeter, and visibility, and required “simple maintenance,” giving small airports a cost-effective way to take advantage of the agency’s GPS satellite navigation approach procedures. “Simple maintenance” meant legally allowing individuals without a general radiotelephone operator license from the Federal Communications Commission to maintain the units.

The FAA then certified MicroTower to provide altimeter setting and visibility as an “AWOS A/V,” satisfying the requirements of FAR parts 135 and 121 operators to meet regulatory weather requirements. That meant MicroTower was certified to issue flight standards-approved visibility information allowing pilots to initiate instrument approaches. This enabled commercial operators, and medevac operators, to fly in and out of small airfields in remote, under-resourced communities, under instrument flight rules. The economies and health care in those communities benefited.

Finally, MicroTower’s ability to transmit on existing unicom and multicom channels relieved those same communities of the expensive and time-consuming regulatory burden of acquiring a second FCC frequency dedicated solely to weather.

MicroTower turned out to be the perfect solution for a moment when the FAA proactively sought to take maximum advantage of the best technology available and deliver it to airports least able to integrate into the burgeoning, technologically advanced national airspace system. Between 1996 and 2011, Wartofsky’s company sold 130 MicroTowers to small U.S. airfields, at a clip of about 10 per year.

So why aren’t most pilots aware of MicroTower? Why isn’t there one installed at a small airfield near you?

In 2009, the FAA changed the way non-federal AWOS vendors are certified. That shift resulted in rescinding the approved weather certification of MicroTower and other non-federal AWOS suppliers.

Some, like Vaisala, temporarily stopped doing business in the United States. Wartofsky chose to focus on the international market between 2012 and 2022, selling another 90 MicroTower units at airports across India, the Philippines, and the Democratic Republic of Congo.

The decertification did not deter pilots like Bolivar’s Tweedy.

“FAA says we must make use of all available information, per Part 91.103. So here we have an unapproved weather system that is available, that’s showing up as real, live weather data, right?” Tweedy said. “Six years of solid, reliable data—we trust that thing.”

And after 20 years, 24 of the 29 units in South Dakota are still operational, despite that state’s notoriously harsh weather. Because of commercial operator considerations, the others were traded out for AWOS facilities, following the 2011 FAA rescission decision. In fact, every MicroTower still in place at an operational airfield is still operating.

Wartofsky has not given up on regaining FAA certification for MicroTower. He said he is encouraged that at least one FAA technical specialist in Oklahoma City has opined that MicroTower is exactly the package that the FAA needs for small, rural GA airports. Perhaps the times have finally caught up with MicroTower.