High-Rise Firefighting Drones: Fact or Fiction
Using firefighting drones for high-rise fires in major metropolitan areas of the United States is not an option. That’s as simple and straightforward as an answer that I can give…At least for now.
Some time ago, I was sent a link to a Heavy Lift UAS that was extinguishing a fire in a high-rise building. While the visual appeal of such a device is no less than spectacular, it is safe to say that too many factors exist to make such an activity, safe, effective, and efficient. So, before we even begin discussing UAS operations in a complex urban environment, let’s step away and just focus on a high-rise fireproof buildings of 75 feet or more in height.
How to Co-ordinate a Firefighting Effort For a High Rise Structure
Firstly, we usually are dealing with the fire of the contents of the building and not the structure itself. The fire code also dictates that high-rise fireproof buildings be sprinkled throughout. Some buildings were built before these fire codes existed. With that being said, fires in these buildings can still be extensive, scorching, and depending on wind conditions, complicated to extinguish. They demand an aggressive multilayered approach from designated stairways of attack, management of the floor above/below, and ventilation.
The potential for life hazards is extreme, with the rapid development of heavy smoke conditions on the fire floor and all floors above. Stairwells, shafts, and even the building’s HVAC system allow for vertical travel of smoke throughout the building and notably to the top level.
The standard attack by an Engine Company is a ”Direct Frontal Assault.” Starting from a stairwell, members operate into the public hall, then to the fire area door, and finally through the doorway into the fire location. These attacks are coordinated dynamic, and fluid. As conditions improve or decline, operational procedures are modified. In the end, the ultimate goal of saving LIFE, then property will be attempted with prominent variables changing the outcomes.
Is it Safe to Fly Firefighting Drones Considering the Chaotic Ground Situation?
Now that we have a fundamental idea of what is happening in the interior of the structure let us start outside the building, from the ground, and work our way up to the window and ultimately fire floor itself.
As firefighters, we are all too familiar with the chaotic scene that happens outside of an incident. In New York City, there are upwards of 90 Fire Department Personnel staging at an all-hands High Rise fire. We can guarantee apparatus, Police, Medical Personnel, civilians, and NEWS media to blanket an area of operation entirely. How do you create a safe space of service for a
Heavy Lift UAS that has the potential to be hundreds of feet in the air? How do you mitigate the risk of a large UAS footprint without the use of accessory personnel, all while operating? Let us just say for argument’s sake, we eliminated all ground issues associated with an incident and focus on our next topic; weight.
The Risks of Flying Large Firefighting Drones with Heavy Payload in Dense Cities
Weight, along with the other three forces of flight, is always a factor in UAS. In level flight, lift equals weight, and thrust equals drag when a UAS flies at a constant velocity. Maintaining a steady trip requires a balance, or equilibrium of all the forces, acting upon a UAS.
A standard 5/8” garden hose carries 0.8 gallons of water per 50 feet. At 500ft high, you would need a lift above the 64 pounds of water weight alone. Now factor in the frame, motor, payload, and battery size capable of lifting that combined weight, and you have more than a solid object hovering above. On your risk versus reward meter, where does your pendulum swing?
Once again, let’s assume that all factors are considered and move to the next issue; Piloting in the human-made “canyons” of a densely populated city.
Tackling Magnetic Interference and Unique Weather Conditions of Big Cities
You attempt to take off, but the wall of buildings surrounding you block out all but 15 degrees of the open sky. GPS is nonexistent due to lack of satellite connections, or if available, multi-path issues tell you that the UAS is on the opposite side of the building instead of the street.
Steel EVERYWHERE throws off the compass on your UAS, and you once again realize that there’s another city of subway and infrastructure is built under your feet. You resort to dropping a handheld boy scout compass to the ground to see if the needle spins(still the most accurate and cost-effective way to check magnetic interference at ground level in my opinion)…Welcome to Big City, USA.
Unique weather systems are created. Vortex-like winds wrap around buildings, and temperature variations fluctuate drastically from grass to concrete to steel. Layered pockets of weather patterns are standard while advancing in altitude.
These are the “typical” factors you face while operating a UAS in a High-rise environment. Factors that can be mitigated through the use of smaller UAS capable of quick relocation and pilots that make informed decisions based on training and real-world experience. While these issues do not disappear, they can be downsized.
Why You Should NOT Use a Drone to Breach a Fire Window
Finally, you make it to the fire window. If the window is still intact and has not self-ventilated, then there is nothing more you can do. These windows can often be very thick and would require a powerful projectile. Do you think it is legal to equip a UAS with a powerful projectile? If you answered yes, I’m sure the ATF would disagree. How would you justify shooting a powerful projectile into the area your members are operating? However, let’s say we could breech the window…Premature ventilation by your UAS can cause negative consequences for those working in the interior. Doing so creates a flow path from the high-pressure fire area to lower pressure areas of public hallways and stairwells. Basically, if you breach the window, you can
put your members on the business end of a blow torch. All horizontal ventilation should be strictly controlled by the Ladder Company Officer operating in the fire area.
Should You Operate a Hose Line into a Building?
If the fire window has failed and access to the interior is viable, do you operate a hose line into the building? “Air Entrapment” can occur where fire and superheated gasses can be “pushed” by air from a hose stream, creating flow paths of products of combustion into unwanted areas of operation. Is the apartment door open? Are you negatively affecting the efforts of firefighters pushing down a charged hallway? Again, you can create that same blow torch.
The drastic difference in exterior and interior pressure along with “canyon” wind also has the potential to create airflow inducement. This effect causes the airflow to be funneled into the relatively narrow gaps and building spaces, increasing wind speeds dramatically. There is also the potential for thermal turbulence from the increased temperatures of the building vs. surrounding air. You would be operating in a multi-directional tornado. I have yet to find a flight controller that would be able to compensate for that, and I would be amazed if there were one.
Conclusion
In short, the risk greatly outweighs the firefighting capability of heavy-lift UAS. I’m not saying this task is impossible but requires the use of advanced systems such as LiDAR and very accurate GPS that can compensate for multi-path issues and correct them accordingly. Before someone says obstacle avoidance… I’m just going to stop that thought by saying It will not work on a highly reflective surface if the sun happens to be on that side of the building. That’s not to say there isn’t a use case for rural and industrial usage, but the urban landscape is a decade away. The human Firefighter in the United States, in conjunction with real-time UAS data, will be the future high-rise firefighting, and High-Rise UAS fire suppression will simply remain a novelty for YouTube.
STAY SAFE! FLY SAFE!
Michael Wall
FDNY Firefighter/ sUAS Operator
Co-Founder of Aerosponse