Frequently Asked QuestionsFAQ

Anything that shares the sky with aircraft—birds, weather, drones, and balloons like ours—carries some risk. Aviation safety is about managing that risk. Our balloons spend most of their flight in the stratosphere, above the altitudes where airliners cruise, and pass through busy airspace only briefly. While they do, each balloon is checked against live positions of nearby aircraft and automatically changes altitude to keep clear. The lightweight payload is designed to reduce harm if an impact occurs.

There has been one midair impact to date after more than 11,000 launches. In October 2025 a United Airlines flight hit one of our balloons. Based on publicly available information, 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 and landed safely. The plane itself later flew to Chicago.

WindBorne works to exceed the safety and operational standards for unmanned free balloons outlined in 14 CFR Part 101. 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 loiter at altitudes from FL300 through FL460. They continue moving up or down through these bands, reducing time spent in commercial airspace.

2. Enhanced Air Traffic Coordination

   In addition to our live tracking dashboard, WindBorne makes automated email reports available to all Air Route Traffic Control Centers (ARTCCs). These reports cover balloons in a given airspace every two hours, with additional alerts as balloons enter and exit. We are also working with other high-altitude operators on shared systems for flight-data coordination.

3. Active Collision Avoidance

   We integrate live global ADS-B data through APIs to identify potential intersections and automatically adjust balloon flight paths to maintain vertical separation from aircraft. The detection and avoidance systems are operational. We continually monitor their output and update parameters to improve performance.

4. Payload Geometry and Mass Optimization

   We have refined the payload housing, adopted lower-density ballast materials, and reduced overall payload mass to reduce cross-sectional density and impact energy.

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 Nations’ International Civil Aviation Organization’s (ICAO) “Rules of the Air,” Appendix 5). 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.) We issue NOTAMs (aviation notices) for every U.S. launch and coordinate with local air traffic control 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 propulsion, FAA rules consider individual payload weight and density, total payload weight, and the force needed to separate the suspension line. Under Part 101, the thresholds include a package over 4 pounds with a weight-to-area ratio over 3 ounces per square inch, any package over 6 pounds, a combined payload over 12 pounds, or a suspension line requiring more than 50 pounds of impact force to separate. The prohibition on hazardous operations applies regardless of these thresholds.

ICAO classifies balloons with a combined payload under 4 kg as light, unless their individual package weight, density, or suspension-line strength puts them in the heavy category. WindBorne’s payload weighs about 2.7 pounds. Individual countries can impose additional requirements, which we account for in our operations.

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:

1. If the active propulsion system fails or loses power, the unmanned aerial vehicle (UAV) would fall out of the sky and could cause damage to something upon landing.
2. Active propulsion usually requires high-speed spinning blades, which present a number of safety hazards.

By contrast, a free balloon does not require any active power to stay aloft.

How does WindBorne approach flying over country lines? ICAO requires authorization from the country of launch. Its rules provide an exception to separate overflight authorization for light balloons used exclusively for meteorological purposes and operated as prescribed by the appropriate authority. National operating conditions still apply. WindBorne holds launch approval at its international launch sites, which span six continents.

The Chinese surveillance balloon shot down in February 2023 was an entirely different kind of platform from our lightweight meteorological balloons. Its large surveillance payload placed it far outside the light-balloon category. The meteorological exception does not apply to surveillance flights.

That is part of why we make live balloon tracking available to government agencies. Government and regulatory partners should be able to see where our balloons are and understand our operations.

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 with data from NOAA’s Global Forecast System (GFS) model.

Our software platform is used by meteorologists, government partners, and research institutions.

Beyond WindBorne Live, we are working with other high-altitude operators on shared systems for flight data. Operators already use one of these systems to flag close passes between their platforms. Another system, a “state bridge,” is in development to give aviation authorities such as the FAA a single source of telemetry from participating high-altitude platforms, which they can distribute internally.

If you’re a WindBorne partner or government agency interested in exploring WindBorne Live, please get in touch to request access.

Since its founding in 2019, WindBorne has conducted more than 11,000 launches. We have coordinated with the FAA throughout the company’s history and file NOTAMs (aviation alerts) for every U.S. launch. We work to exceed the safety and operational standards for unmanned free balloons outlined in 14 CFR Part 101.

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 a loss of satellite communication beyond 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, based on publicly available information, 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. Our aircraft-safety answer describes the four additional measures: reduced exposure in commercial airspace, enhanced air traffic coordination, active collision avoidance, and payload geometry and mass optimization.

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.

Backtests for both WeatherMesh-6 models are available from April 2025 to present, so you can score on your own variables and regions before going live. Our blended model MetaMesh dynamically recalibrates its weights as new input models arrive, so historical backtests would not accurately represent live model performance. For this reason, MetaMesh is available as a live forecast product only.

WeatherMesh-6 is our AI forecast model, trained on proprietary observations and running hourly. MetaMesh is our blended point forecast product: it combines HRRR, GFS, GFS Ensemble, IFS, IFS Ensemble, AIFS, AIFS Ensemble, and WeatherMesh models with dynamically learned weights that adapt by variable, lead time, region, and season. WeatherMesh is the raw AI signal. MetaMesh is the best-of-breed consensus. It updates on a rolling basis with hourly time steps out to 15 days, optimized for over 5,349 METAR stations with dynamic global coverage.

REST API with JSON and Zarr responses for point and gridded data, plus a Python SDK. Most teams can begin pulling data within a day of onboarding. No portals or file downloads required. View API documentation.