No, our balloons are designed to avoid impact with aircrafts and are lightweight enough to be safe even in the unlikely event of a midair collision.
There has been one midair impact to date after more than 4,000 launches. In October 2025 a United Airlines flight hit one of our balloons. We are grateful that to our knowledge there were no serious injuries and no loss of pressurization. The flight, which was en route from Denver to Los Angeles, diverted to Salt Lake City. The plane itself later flew to Chicago.
WindBorne has always strived to exceed the safety and operational standards outlined in 14 CFR Part 101, which governs high-altitude balloon systems. Following the United Airlines impact, WindBorne immediately implemented four additional safety measures to further reduce the possibility of any future aircraft-balloon interactions and to mitigate potential harm should an impact occur again:
1. Reduced Exposure in Commercial Airspace:
Balloons no longer maintain superpressure neutral buoyancy within the primary commercial altitude bands (FL300–FL400), cutting total time spent in that zone by approximately 50% across our fleet.
2. Enhanced Air Traffic Coordination:
In addition to the live dashboard previously available to air traffic control organizations, WindBorne now provides automated reports via email every two hours for all balloons in a given airspace. Additional alerts are issued as each balloon enters and exits that airspace.
3. Active Collision-Avoidance Development:
We have integrated live global ADS-B data through an API feed to identify potential intersections and automatically adjust flight paths. The detection system is operational, and avoidance algorithms are in active testing and near deployment.
4. Payload Geometry and Mass Optimization:
We are refining the design of the payload housing to reduce cross-sectional density and impact energy. This includes testing lower-density ballast materials and further reducing overall payload mass.
We’re proud to be fully compliant with both U.S. airspace regulation (via the Federal Aviation Administration’s (FAA) Part 101), as well as international airspace regulation (via the United Nation’s International Civil Aviation Organization’s (ICAO) "Rules of the Air,” Appendix 4). Both entities set safety rules and guidelines for aircraft, as well as the operation of free-floating balloon systems like ours.
In addition to following FAA and ICAO rules and recommendations, we go above and beyond to be good stewards of the sky. For example, we maintain active lines of communication with the FAA to ensure our operations satisfy all relevant regulatory requirements. We also provide government partners with direct access to our comprehensive, real-time balloon tracking system via our proprietary software, WindBorne Live. (WindBorne government partners and collaborators can contact us for access here.) Additionally, though not required, we frequently issue Notices to Airmen (NOTAMs) and coordinate with local air traffic control when conducting launches to keep relevant partners informed of our operations.
So, what’s the gist of balloon requirements? WindBorne’s Global Sounding Balloons (GSBs) fall under a few categories. First, they’re meteorological balloons, meaning they’re used for gathering weather data. Second, they don’t have “active propulsion,” meaning our balloons don’t use any type of motor or onboard fuel to fly. Instead, our balloons are powered through a combination of a small solar panel and the autonomous ability to surf the wind by changing altitude by dropping ballast or releasing gas.
For balloons without active propulsion (like ours), the FAA and ICAO define a threshold for the payload weight, below which the balloon is considered light enough to not pose significant hazards in the air or on landing. If the balloon is below this weight, which is less than 4 pounds (2 kg) in the U.S. and internationally, then the balloon falls into the exempt category (by comparison, the average Canada goose weighs 8.5 pounds). FAA and ICAO regulations also deem a balloon exempt if it has a payload weighing less than 6 pounds (3 kg) and has weight-to-size ratio of less than three ounces per square inch (13 g/cm^2) on any surface. Per these rules, WindBorne balloons fall into the exempt category globally (barring any unique, temporary restrictions that sometimes affect specific regions).
Why is the presence (or lack) of active propulsion so significant? Active propulsion can make unmanned aerial vehicles (UAVs) like drones more dangerous for several reasons:
By contrast, a balloon does not require any active power to stay aloft.
How does WindBorne approach flying over country lines? ICAO permits lightweight, meteorological flights like ours over countries other than the country of launch, as long approval for a launch was obtained in the launch country. WindBorne routinely and successfully receives this approval across all of our international launch sites, which span three continents.
It’s worth noting that the suspected China balloon that the U.S. Air Force shot down in February 2023 was not in compliance with ICAO regulations, which is why it caused an international incident. It was an entirely different type of balloon than WindBorne’s. The China balloon’s payload was estimated by the North American Aerospace Defense Command (NORAD) to weigh several thousand pounds, about 1,000x heavier than WindBorne’s balloon.
Incidents like this underscore why WindBorne is proud to make easy-to-use, live balloon tracking software available to government agencies like NORAD. We believe it should be easy for government and regulatory partners to track the location of all balloons and are excited to continue supporting this transparency.
Regulations can always shift over time; we at WindBorne will always be committed to being fully compliant and communicative stewards of the sky.
At WindBorne, we are deeply committed to offering transparent, seamless visibility into the location of our active and past global sounding balloons (GSBs) to our government partners, regulators, and customers. This is why we built our state-of-the-art data viewer, WindBorne Live.
WindBorne Live enables users to view our global constellation, individual GSBs, search soundings by geographic region, and compare GSB readings to NOAA and the Global Forecast System (GFS)’s model data.
Our software platform is regularly used by hundreds of meteorologists and partners, including the North American Aerospace Defense Command (NORAD), the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense, the National Center for Atmospheric Research (NCAR), the U.S. Air Force, and the Scripps Institution of Oceanography.
If you’re a WindBorne partner or government agency interested in exploring WindBorne Live, please get in touch to request access at windbornesystems.com/access.
Since its founding in 2019, WindBorne has conducted more than 4,000 launches. We have been coordinating with the FAA for the entire history of the company and file NOTAMs (aviation alerts) for every balloon we launch and we exceed the safety and operational standards outlined in 14 CFR Part 101, which governs high-altitude balloon systems. We take airspace safety very seriously.
In addition to making all of our active and past global sounding balloons (GSBs) viewable and trackable by our government and regulatory partners (see more in our FAQ on location data sharing), WindBorne balloons are also equipped with several key safety and security features.
By design, WindBorne maintains both autonomous and manual control over each individual balloon at all times. Our proprietary AI-powered flight system is designed to enable balloons to autonomously navigate toward targets with the option to dynamically retarget as needed. WindBorne Atlas, our global constellation, is monitored by WindBorne personnel 24-7, with the ability to make manual, expert intervention at any time from our Mission Control Center (MCC).
WindBorne has achieved unparalleled precision for balloons without active propulsion. Our constellation’s unique, smart altitude control allows our balloons to autonomously shift into different wind layers, catch the right currents, and reach their assigned target. A 2022 WindBorne balloon, for example, collected data directly within the eyewall of Hurricane Ian. Our navigation control also allows us to smoothly steer clear of specific regions, such as active conflict zones.
In the unusual event that a WindBorne balloon experiences an issue, such as the loss of satellite communication of a certain threshold, our platform has systems in place to automatically and safely conclude flights.
In October 2025, a United Airlines flight impacted one of our balloons. The plane landed safely and to our knowledge there were no serious injuries. Within 24 hours, our team of engineers shipped out new flight software and the R&D team created our first string bean ballast (named after its long, string bean-like appearance). Our goal was and continues to be: to create software that reliably gets balloons away from planes, and hardware that minimizes potential damage in the worst case collision. Following the United Airlines impact, WindBorne immediately added four additional safety features.
1. Reduced Exposure in Commercial Airspace:
Balloons no longer maintain superpressure neutral buoyancy within the primary commercial altitude bands (FL300–FL400), cutting total time spent in that zone by approximately 50% across our fleet.
2. Enhanced Air Traffic Coordination:
In addition to the live dashboard previously available to air traffic control organizations, WindBorne now provides automated reports via email every two hours for all balloons in a given airspace. Additional alerts are issued as each balloon enters and exits that airspace.
3. Active Collision-Avoidance Development:
We have integrated live global ADS-B data through an API feed to identify potential intersections and automatically adjust flight paths. The detection system is operational, and avoidance algorithms are in active testing and near deployment.
4. Payload Geometry and Mass Optimization:
We are refining the design of the payload housing to reduce cross-sectional density and impact energy. This includes testing lower-density ballast materials and further reducing overall payload mass.
WindBorne balloons (officially named Global Sounding Balloons or GSBs) are purpose-built to be both extremely sustainable and cost-effective. We’re proud to power the only atmospheric sensing technology that can sustainably and safely observe the atmosphere anywhere around the world.
While a WindBorne balloon uses a similar amount of material as a conventional weather balloon, our balloons’ unique long-duration capabilities enable them to gather up to 150x more data per cost dollar than alternative collection methods such as conventional weather balloons and aircraft-carried dropsondes. (An aircraft-carried dropsonde is a sensing device with a small parachute, which piloted aircraft can carry and release over oceans or directly into extreme weather. This is a highly costly effort that poses risk to human operators.)
How is that possible? Conventional weather balloons, which are typically single-use, can only ascend vertically from a launch point on land, travel for a few hours to collect one vertical slice of atmospheric data, pop, and descend straight back down. By comparison, WindBorne balloons can fly for weeks at a time, even double-circumnavigating the globe, to gather dozens of vertical profiles in a single flight. This is the result of our team’s rigorous engineering efforts to reduce parts and waste, as well as our unparalleled, proprietary full-stack flight system, which spans hardware, communications technology, and proprietary, autonomous flight software.
While we’re proud of our sustainability break-throughs, we see significant room for improvement, which is a top priority. As WindBorne Atlas, our global constellation scales, WindBorne is committed to ultimately collecting at least 80% of our balloons after flight to enable as much reuse and recycling as possible. We’re uniquely positioned to do this thanks to the autonomous nature of our flight system, which can navigate balloons to chosen landing sites.
In the meantime, WindBorne continues to be plastic negative. In partnership with rePurpose Global, we retrieve and recycle 2x more plastic than we use. We also continue to innovate on our underlying balloon design and manufacturing processes,which are fully California-based and compliant, in order to continuously reduce our apparatus size and minimize material use and waste.
WindBorne Systems is based in Palo Alto, Calif. Our technology is invented, designed, and manufactured in the USA.
© 2024 by WindBorne Systems