The bid to deploy cloud seed flares on small drones from Rainmaker Technology has been met with resistance from the airline Pilots Union.
The FAA decision shows how regulators view weather changes due to future unmanned aerial systems. Rainmaker's bets on small drones fall on balance.
The Air Line Pilots Association (ALPA) told the FAA that the Rainmaker petition “cannot demonstrate comparable levels of safety,” and raised “extreme safety risks.”
However, Rainmaker CEO Augustus Doricko said that all public documents are not private documents submitted to the FAA outlining company safety data and risk mitigation, and that all union objections are based solely on public announcements.
Rainmakers are seeking exemptions from rules that prohibit small drones from carrying dangerous goods. The startup was submitted in July and the FAA is not yet in control. Instead, they issued a follow-up request for information and pressed operational and safety details.
In its filing, Rainmaker proposed dispersing precipitation-stimulating particles with one flare type, one “burn-in-place” and another evacuable elijah quadcopter. The Elijah's maximum altitude is 15,000 feet of MSL (measured from sea level), and is located inside the controlled airspace where commercial passenger aircraft usually fly. Drones need permission from Air Traffic Control to fly within this bubble.
The Rainmaker petition states that it will operate in Class G (uncontrolled) airspace unless otherwise permitted. ALPA notes that the filing does not clearly state where the flight will occur or which altitudes will be used. However, Doricco said the documents filed with the FAA will be held in airspaces previously determined to be safe by the aviation authorities, in addition to flights that are constrained to the maximum height of the 15,000-foot MSL. Alpa did not reply to TechCrunch's request for comment.
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The union is also opposed to Flare itself, citing concerns about foreign debris and fire safety. ALPA notes that the petition does not include trajectory modeling or analysis of evacuable casings regarding the environmental impact of chemicals.
“In relation to their objections to the use of flares, independent bodies like the EPA of this administration, as well as several state divisions of natural resources, have been studying the dispersion and environmental safety of the materials used to sow cloud seed for over 70 years, and have not seen any adverse effects from sowing cloud seed,” Doricko said.
Sam Kim, Air Regulation Manager at Rainmaker, argued that the company respects the pilots' union and “continue to strengthen its relationship with the organization,” but that it “indicating a lack of understanding of why Rainmaker applied for this exemption.”
“The use of flares in unmanned systems is for research purposes only in controlled flight environments and is not part of the larger ongoing operation,” Kim added.
Dolicco said that typical rainmaker surgery disperses 50-100 grams of silver iodide and is much less in flights with flares, but an hour-long flight of a commercial plane releases burning out volatile organic matter, sulfur oxides and kilograms of soot.
“Rainmakers are interested in doing the best and responsible atmosphere research, comparing them to their own aerosol dispersion systems that replace flares and emit only silver iodide.
“Regarding ALPA's concerns regarding coordination between the aviation authorities and airspace, our flight operations consist of collision avoidance systems that include broadcast signals, intentional coordination with local ATCs, certified pilots, and electronic and physical observers,” he said.
However, Rainmakers say the flights occurred in rural areas and in facilities owned by private property, and “rainmakers have developed close working relationships.”
Cloud seeding is already occurring primarily in the western United States, and is airplane in cooperation with state agencies. Ski resorts commission businesses that help keep the rides white, and in winter, irrigation and water districts fly to build snowmen and supply reservoirs during spring melting.
Common practices of cloud seed date back to the 1950s. Scientists have discovered that spraying small particles onto certain clouds can induce precipitation. Typically, cloud seeding operations use silver silver and silver for the particles. This is primarily because it mimics the shape of ice crystals.
When silver iodide particles hit a supercooled water droplet, the droplets freeze rapidly as the water is already below the freezing point. When ice crystals form, in similar circumstances, liquid water droplets can grow faster than liquid water droplets and rapidly if the conditions are correct. Furthermore, rapid growth helps to stick to crystals longer than water droplets. This can evaporate before there is a chance of falling as precipitation.
The rainmaker twist – doing this work with a drone instead of a pilot – could prove safer in the long run. The company notes that flight profiles are tightly bounded to boundaries, overseen by remote pilots and trained crews, and other safety checks have been put into place in rural areas.
What happens next depends on whether the FAA believes these mitigations are sufficient. But even though that has been decided, the agency response will likely set the tone for a new cloud seed approach.
9/13/2025: Story has been updated to include Rainmaker's comments from founder and CEO Augustus Doricko and Sam Kim of Rainmaker's Aviation Regulatory Manager.