The Forest Service is evaluating two high-altitude drones to help wildland firefighters

Illustration of how a Thunderhead Stratospheric balloon can help wildland firefighters.

The US Forest Service is partnering with NASA to evaluate the use of two high-altitude, long-endurance drones to improve situational awareness for wildland firefighters.

1. A balloon

Last week, a balloon loaded with a sophisticated array of electronics hovered 60,000 feet above the Moose Fire in Idaho. Its mission was to help firefighters improve and maintain situational awareness. Some of them may have seen the bright object the size of a football stadium, even though it was more than 18 kilometers above the incident.

The company that built and operates the plane, Aerostar, calls it STRATO, or Strategic Radio and Tactical Overwatch, a technology that is in the research and development phase.

Raven Aerostar Balloon
File photo of a partially inflated Raven Aerostar balloon just after launch. Still image from Aerostar video.

The STRATO is essentially a giant mylar balloon with solar panels, batteries, radio equipment, cameras and sensors. It has the ability to collect infrared and visual data, broadcast an LTE (cell phone) signal, has a broadband radio that can enable push to talk communications, and can operate a WiFi network. The huge helium balloon can hover over an incident in the stratosphere taking pictures, providing data to incident managers and providing communication options to incident command post and ground crews.

Aerostar Thunderhead Moose Fire Stratospheric Balloon
Flight path of an Aerostar Thunderhead stratospheric balloon over Moose Fire the week of August 7, 2022.

Last October, Fire Aviation wrote about the system operated by Aerostar, a company based near Sioux Falls, South Dakota, which has worked with lighter-than-air technologies since 1956. We reached out to the communications manager of the company, Lisa McElrath, who told us that in June, July and August of 2021, they launched one of their Thunderhead balloons from South Dakota and flew it west to monitor the fires of forest. While covering more than 16,000 miles during its 70-day flight, it engaged in finding stations above four active fires for the company’s research and development. It collected visible and thermal imagery data over extended periods of time on the Robertson Draw Fire (Montana), Dixie Fire (California), Dixie-Jumbo Fire (Idaho), and Dry Gulch/Lick Creek Fire (Washington). .

In October, we asked Ms. McElrath if Aerostar had cooperated with federal land management agencies to map the fires. She said not yet, but that representatives from the National Interagency Fire Center had contacted them and expressed interest in discussions after the fire season slowed. But this year, the US Forest Service is officially cooperating in the pilot project.

“We can provide real-time images of the ball today in both visible and infrared,” Ms McElrath said. “Going forward, the goal would be to automate the detection and upload of critical images, fire perimeters, probable fire starts and other key information via on-board processing so that more actionable information are available. We see stratospheric balloon technology as the key to cost-effective, scalable wildfire monitoring that shortens the time between new fire detection and response. Indeed, balloons can alert firefighters to a new fire while it is still small, before the fire becomes something interesting and very expensive.

She said the balloons can also act as radio repeaters for ground personnel and could collect information from tracking devices about firefighting assets which could then be displayed on a map.

More flights over the fires are planned, said Sean Triplett, team leader for tools and technology, US Forest Service, Fire and Aviation Management. He said NASA is matching the funding the Forest Service is spending on flights this year.

2. Fixed-wing aircraft

SULE HALE-UAS by Swift Engineering
SULE HALE-UAS from Swift Engineering. Quick engineering photo.

Another high-altitude, long-endurance (HALE) aircraft the Forest Service is considering is Swift Engineering’s SULE HALE-UAS, capable of staying aloft for more than 30 days at a time. The Forest Service, again in partnership with NASA, has entered into a contract with the company and as of March 31, 2021, they have performed more than 10 demonstrations of the solar-powered fixed-wing aircraft.

The key to long-duration flight using solar power in an airplane is having an upper surface area large enough for the solar cells needed to power the electric motors day and night, using a battery for nighttime operations. Big wings mean more solar cells, but also more wind resistance. So the answer, using today’s technology, is to fly very high at 60,000 to 70,000 feet where the air is thin, the sunlight on the solar panels is strong, and there’s less wind resistance.

The SULE, which made its first flight in July 2020, has a wingspan of 72 feet, operates at 70,000 feet and can carry a payload of 15 to 22 pounds.

“A series of medium and high altitude flights are underway,” Triplett told Fire Aviation on Wednesday. “At this stage, the platform only provides remote sensing products. However, if successful, additional systems can be incorporated. These additional systems could include a radio system to provide connectivity to allow tracking of firefighting resources in the field in addition to live imagery of the fire.

Triplett said one of the benefits of having NASA on the project is that they can handle the airworthiness of the aircraft and interactions with the FAA.

The Swift Engineering video below shows what could be the SULE’s first flight two years ago.

A step towards the holy grail of wildland firefighter safety?

Our view is that providing wildfire supervisors with the real-time location of fire and firefighting resources is the holy grail of wildfire fighting safety. The lack of this information has resulted in at least two dozen firefighter deaths. These high-altitude, long-endurance aircraft 13 miles above the fire could be an important link to transmit live video of the fire to personnel and provide radio connectivity for tracking firefighting assets. fire on the ground, even when they are in a rough and steep topography. Of course, the resources would need to have the necessary hardware to transmit the coordinates of their locations.

The John D. Dingell, Jr. Conservation, Management, and Recreation Act, which went into effect March 12, 2019, required that before March 12, 2021 the five federal land management agencies “…develop consistent protocols and plans for the use of unmanned aircraft system technologies on wildfires, including the development of real-time maps of the ‘location of forest fires.’

Although this technology has proven itself, real-time mapping seems to be far from being used routinely, at least within federal agencies. But at the state level, the governor of California has requested $30 million in his next budget for 31 positions and funds for the state’s office of emergency services to operate the real-time intelligence system ( FIRIS). aircraft that have shown they can provide real-time fire mapping information. A pilot program for FIRIS began on September 1, 2019 with funding secured in the 2019-2020 California State budget. This year, two FIRIS ships assisted the firefighters.


The Dingell Act also required that the five federal land management agencies “jointly develop and operate a tracking system to remotely locate fire resource positions for use by wildland firefighters, including, at a minimum, all fire resources assigned to Federal Wildfire Type 1 Incident Management Teams,” again, due before March 12, 2021.

Other High Altitude Solar Planes

One aircraft with which the Forest Service is not involved is the Zephyr, manufactured by AIRBUS. It is an unmanned, solar-powered, fixed-wing aircraft designed to stay aloft at high altitudes for months.

AIRBUS Zephyr, stratospheric unmanned aerial vehicle. Photo by Airbus.

On its final test flight which began June 15, 2022, the Zephyr took off from the US Army’s Yuma, Arizona, test range and has since flown over the Yuma Test Range and Kofa National Wildlife Refuge. Now, 63 days later, the flight has broken Zephyr’s previous record of 25 days which it set in August 2018. When we checked on August 17, it was cruising at a ground speed of 40 knots at 70,500 feet at the above the Earth.

ZULU82 Zephyr flight path
Flight path of the ZULU82 Zephyr, a solar-powered unmanned aircraft on August 16, 2022, day 62 of a flight that began June 15, 2022.

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