The quick answer is that our balloons are designed to be sufficiently lightweight that they are safe even in the unlikely event of a collision.
Before we dive into collision physics, it’s worth zooming out to note that we’re fully airspace compliant, domestically and internationally (more on this in our next FAQ). We go above and beyond to be good stewards of the sky: we take extra measures to coordinate with airspace authorities when we launch balloons. We also openly share the real-time location data of our aloft constellation with our government and regulatory partners, so they can easily and precisely view our balloons’ location at any time.
At its heaviest, a WindBorne balloon is about 2.4 pounds, or ~1 kg. Throughout flight, the balloon drops ballast and gets progressively lighter. By comparison, the average Canada goose weighs 8.5 pounds. The FAA’s focus on weight – they allow balloons under 4 pounds – is driven by lower mass meaning a lower energy and thus safer collision.
Now, back to the question of aircraft: if a balloon and airplane were to get close, generally the airflow around the plane would push a light object like a WindBorne balloon away.
In the unlikely event of an actual collision with an aircraft, our balloon would disintegrate upon impact. This is due to the light, dispersed composition of the ballast. The ballast is the heaviest part of our balloon, which is primarily sand housed in the same thin film that our envelope (the balloon part of the balloon) is made of. The film is 20 microns thick, less than half the thickness of a single human hair, and is built to break on impact to disperse the energy. This interaction would be different, for example, if the object were a hard, dense solid (like a brick or ball) and not a balloon. However, our unit is more akin to one of the 40 million ducks worldwide, which weigh a similar amount to our balloons and share the sky with aircraft every day.
Importantly, our balloons do not fly in flocks, unlike birds, since we have no incentive to achieve a “flock effect” (that level of balloon density would be redundant for data collection). Instead, our balloons prefer to fly solo, which means they don’t carry the same potential for hazard that multiple birds do: the ability for multiple strikes to one aircraft. In other words, the 2009 Hudson River plane landing incident couldn’t be repeated with a WindBorne balloon: our balloon is 100x lighter than even a relatively small flock of geese.
As an extra precautionary measure, we also don’t fly at low altitudes around highly populated areas. (We’re also not incentivized to do this since weather measurement systems like ground stations are usually present throughout densely populated areas).
Update: In light of the incident with UA1093 we are rapidly rolling out new safety systems. While no one was seriously injured to our knowledge, we deem this level of plane collision damage to be unacceptable. You can read more on our blog here: https://windbornesystems.com/blog/ua-1093
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.
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. The balloons’ unique, smart altitude control allows them to autonomously shift into different wind layers to catch the right currents in order to reach their assigned target. A WindBorne balloon, for example, collected data directly within the eyewall of Hurricane Ian. We can also smoothly avoid specific regions. For example, we choose not to fly over active conflict regions.
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.
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.
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