What should a drone pilot do immediately if smoke or fire is detected during flight?

The immediate priority is to land the UAS as quickly and safely as possible, directing it away from people, structures, and flammable material. The remote pilot in command should identify the nearest suitable landing zone, reduce altitude decisively, and execute an emergency landing without delay. According to 14 CFR Part 107, the remote pilot in command is responsible for the safe outcome of the flight, which includes minimizing harm to persons and property on the ground during an emergency.

Why are lithium polymer battery fires considered especially dangerous on UAS?

Lithium polymer (LiPo) batteries can undergo a process called thermal runaway, in which an internal cell failure generates intense heat that causes adjacent cells to fail in a cascading reaction, producing flames and toxic gases that are extremely difficult to extinguish. Unlike conventional fires, a LiPo fire can reignite even after appearing to be out, making post-landing handling especially hazardous. Remote pilots should be familiar with proper battery storage, inspection, and disposal procedures to reduce the risk of in-flight thermal events.

What's the difference between an electrical fire and a battery fire on a drone, and does the response change?

An electrical fire typically originates from a short circuit, overloaded wiring, or a failing electronic speed controller, while a battery fire stems from internal cell damage, overcharging, or physical impact causing thermal runaway in the LiPo pack. The immediate in-flight response is the same for both — land immediately and move bystanders away from the area — but post-landing actions differ slightly, as a battery fire may require containment in a fire-safe bag or bucket of sand rather than water, which can react dangerously with lithium. Pre-flight risk management, outlined in FAA guidance on UAS operations, includes inspecting all electrical components and batteries for damage before each flight to reduce the likelihood of either type of fire.

In-Flight Fire or Smoke Response for Drone Operations

Fire or smoke aboard a crewed aircraft is one of aviation's most serious emergencies. While a small drone does not carry passengers, an in-flight fire or smoke event on an sUAS presents its own urgent hazards: a burning lithium polymer (LiPo) battery can eject molten material, release toxic gases, or cause a sudden, uncontrolled descent into people or property below. Understanding why fires start, how to recognize them quickly, and what to do in the seconds that follow is a core competency for any responsible Remote Pilot in Command (RPIC).

The FAA's Part 107 rules govern small unmanned aircraft systems (sUAS) weighing less than 55 pounds. While the regulations do not spell out a step-by-step emergency checklist the way Transport Category aircraft manuals do, they do establish that the RPIC is responsible for the safe outcome of every flight. That responsibility includes recognizing emergencies, executing the appropriate response, and — critically — reporting certain incidents. This article walks through the full picture: causes, recognition, in-flight action, post-landing response, and regulatory reporting obligations.

Why Fires and Smoke Occur on sUAS

The vast majority of sUAS fire events trace back to the power system. Most modern consumer and commercial drones use lithium polymer (LiPo) or lithium-ion (Li-ion) battery packs because they offer a high energy-to-weight ratio. That same energy density creates risk. A process called thermal runaway can begin when a cell is overcharged, deep-discharged, physically punctured, or subjected to excessive current draw. Once one cell in a pack begins to overheat, it can cascade to adjacent cells with alarming speed. During thermal runaway, the battery releases flammable gases and can reach temperatures exceeding 1,000 °F, producing visible smoke, flame, or both.

Additional ignition sources include:

Motor or ESC failures: A seized motor or a failing Electronic Speed Controller (ESC) can draw enormous current, overheating wiring and solder joints.
Wiring damage: Chafed or improperly rated wires can arc, creating localized heat sources near fuel lines or plastic airframe components.
Foreign object ingestion: A propeller strike that drives debris into the airframe can puncture battery cells or damage ESC connections.
Poor maintenance: Loose connector pins create resistance, and resistance under load creates heat. Batteries with swollen (puffed) cells are already in a compromised state and far more prone to failure.

Recognizing an In-Flight Fire or Smoke Event

Unlike a cockpit crew, an RPIC observes the aircraft from the outside, which can make early fire detection more challenging — but also grants a broader view of the aircraft's exterior. Warning signs include:

Visible smoke trailing from the aircraft body, motor arms, or battery bay.
Unusual odor reaching the ground crew (acrid or burning-plastic smell, especially near the landing zone).
Sudden, unexplained loss of power or erratic motor behavior on telemetry.
Rapid, unexpected battery voltage drop shown on a ground control station (GCS).
Visible discoloration or melting of airframe plastic observed through binoculars or a video feed.
GCS warnings for overcurrent, high motor temperature, or ESC fault codes.

Early recognition is the single biggest factor in a successful outcome. Brief pre-flight agreements with your visual observer (VO) — including a specific call-out phrase like "I see smoke" — ensure the crew responds as a unit rather than experiencing confusion about whether what they are seeing is vapor or actual combustion.

In-Flight Response: The Decision Sequence

The guiding principle in any sUAS emergency is to get the aircraft on the ground as rapidly as possible while minimizing risk to people, property, and infrastructure. For a fire or smoke event, speed is even more critical because thermal runaway can progress from early smoke to full battery ejection in under 30 seconds.

Step 1 — Recognize and Announce

As soon as any crew member identifies smoke or signs of fire, they call it out clearly. The RPIC confirms they have control of the aircraft and understands the situation. This takes one or two seconds and prevents the crew from working at cross-purposes.

Step 2 — Clear People and Property

Before initiating descent, assess what is directly below and downwind of the aircraft. If possible, use horizontal flight to move the UAS over an open area — pavement, bare earth, or a pre-designated emergency landing zone — away from spectators, vehicles, or structures. Do not maneuver the aircraft over people even briefly if an alternative exists. Part 107.39 prohibits flight over moving vehicles and people without a waiver, and the spirit of that rule applies with even more urgency when the aircraft is on fire.

Step 3 — Descend Immediately

Execute a rapid, controlled descent. Do not attempt to nurse the aircraft back to a convenient landing spot if doing so prolongs flight and increases the probability of mid-air battery failure. A short crash-landing in a safe area is far preferable to a mid-air disintegration over people or roads. Some GCS systems have an emergency landing function; use it if it is faster than manual control, but never sacrifice situational awareness to navigate menus.

Step 4 — Cut Power on Landing

The moment the aircraft touches down, cut throttle and, where possible, cut all power to the system. Removing electrical current to a thermally compromised battery may slow (though not stop) the progression of thermal runaway. Stand clear immediately — a burning LiPo pack can eject flaming material horizontally and without warning.

Post-Landing Response

Once the aircraft is on the ground, the emergency shifts from an aviation emergency to a fire-safety emergency. Key actions include:

Do not approach immediately. Wait at least 30 to 60 seconds before moving toward the aircraft. Burning LiPo cells can explode or eject material during this window.
Use appropriate extinguishing media. Water or dry sand can be used to cool a burning LiPo. Standard dry chemical fire extinguishers (ABC type) can suppress flames but may not cool the battery sufficiently to prevent re-ignition. Halon extinguishers are effective but not always available. Never use CO2 alone on a lithium battery fire — it does not cool the cells and re-ignition is highly likely.
Avoid breathing smoke. Burning lithium batteries release hydrogen fluoride and other toxic byproducts. Stay upwind and, if available, use respiratory protection.
Once cooled, isolate the battery. Place the battery in a fireproof LiPo safety bag, a metal container with a lid, or — in a field expedient — a bucket of water. Do not transport a hot or still-smoking battery in an enclosed vehicle.
Notify authorities if needed. If the fire poses any risk to property or public safety, call 911 and inform the fire department that a lithium battery is involved.

Regulatory Reporting Requirements

Part 107.9 requires the RPIC to report an accident to the FAA within 10 days if the operation results in: serious injury (as defined in 49 CFR 830.2, e.g., hospitalization for more than 48 hours, a fracture of a bone other than fingers, toes, or nose, severe hemorrhages, internal organ injury, or second/third-degree burns over 5% of the body) to any person, or property damage (other than to the UAS itself) exceeding $500 in value. A battery fire that damages a vehicle, a building, or injures a bystander almost certainly meets this threshold. Reports are filed using the FAA's online Drone Zone portal or by contacting the appropriate FAA Flight Standards District Office (FSDO). Failing to report a qualifying accident is itself a regulatory violation.

Even when an incident falls below the 107.9 reporting threshold, voluntary reporting through the FAA's Aviation Safety Hotline or NASA's Aviation Safety Reporting System (ASRS) is strongly encouraged. These reports are confidential, shield pilots from certain enforcement actions, and contribute to safety data that benefits the entire sUAS community.

Key Numbers and Rules

55 lb — maximum takeoff weight for Part 107 sUAS operations without further authorization.
10 days — deadline to report a qualifying accident under 14 CFR Part 107.9.
$500 — property damage threshold (excluding the UAS) that triggers the accident reporting requirement.
30 seconds or less — approximate window for thermal runaway to fully develop in a compromised LiPo pack; highlights why immediate descent is critical.
Part 107.39 — prohibits flight over moving vehicles and non-participating people; applies fully during emergency maneuvering.

Common Test Traps

Assuming a low-weight UAS can't cause reportable damage. Even a small drone landing on a car hood with a burning battery can easily cause more than $500 in damage. The reporting threshold is about dollar value, not aircraft size.
Confusing the 10-day rule with immediate notification. Part 107.9 gives 10 calendar days for written reporting to the FAA, but this does not preclude — and does not replace — calling 911 for an active fire or injury situation.
Believing CO2 extinguishers fully handle a LiPo fire. CO2 suppresses flames but does not cool the battery, making re-ignition likely. The test may present CO2 as the sole correct answer; understand its limitations.
Neglecting to plan the emergency landing zone before flight. Part 107 requires the RPIC to assess the operating environment prior to flight. Failure to identify a safe emergency landing area is a pre-flight planning error, not just an in-flight error.
Thinking property damage to the UAS itself counts toward the $500 threshold. The regulation explicitly excludes damage to the sUAS. Only damage to other property — or serious injury to a person — triggers the reporting requirement.