UA.V.C.K2: Characteristics and potential hazards of lithium batteries.

ACS Area V — Operations Task C: Emergency Procedures References: ACAdvisory CircularCloseFAA guidance that explains acceptable ways to comply with rules or understand FAA procedures. 107-2; FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-H-8083-25; FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-G-8082-22; SAFOsSafety Alert for OperatorsCloseFAA safety alert that shares operational safety information. 09013, 10017, 15010

Key Concepts

Identify and assess battery hazards before flight (§107.49)

Lithium batteries power most small UASSmall Unmanned Aircraft SystemCloseA small drone plus the control and communication links used to operate it., so their condition is part of the mandatory preflight familiarization, inspection, and actions required by §107.49. As Remote PICRemote Pilot in CommandCloseThe certificated remote pilot responsible for the Part 107 operation., you must assess the operating environment, including local weather, airspace/flight restrictions, the location of people and vehicles, and other ground hazards, before beginning operations. This preflight assessment explicitly includes equipment condition and operational limitations—capture battery health, state of charge, and any limits your aircraft imposes when you evaluate “condition of the equipment.” Crewmember briefings are also part of this preflight requirement, ensuring everyone understands how power-system issues will be handled in flight.^[3]

Use a structured risk process to capture battery-related hazards in your plan. In the hazard column, document relevant factors such as current/forecast weather, equipment condition, crew fatigue/awareness, terrain/obstacles along normal and contingency routes, risks of flying over people, and—if operating at night—visibility of anti-collision lighting for at least 3 statute miles. Then, for each hazard, list its causes and effects, assess likelihood and severity, and define your emergency or contingency procedures if the event still occurs. This turns abstract “battery risk” into concrete, testable steps in your operations manual and crew briefings.^[2]

Electrical and fire hazards: controls that also apply to battery events

Electrical and fire hazards demand disciplined controls. While written for helicopter hot refueling, the underlying safety principles translate directly to sUASSmall Unmanned Aircraft SystemCloseA small drone plus the control and communication links used to operate it. operations around energy sources: avoid ignition risks and uncontrolled electrical discharge, and account for weather. Key controls include:

• No electrical storms (thunderstorms) within 10 nautical miles; lightning can propagate far beyond the cell core of a storm.^[6]
• Place applicable electrical/electronic equipment in standby-off to preclude electrical discharge or other fire hazards; avoid unnecessary transmissions that could create arcs.^[6]
• Prohibit smoking anywhere near aircraft and energy sources.^[6]
• Recognize that operations with fuels and electricity carry hazards tied to quality control, weather, static electricity, bonding, and spill/fires potential—plan procedures that address each of these elements when handling or staging aircraft power systems.^[6]

Practical takeaway: incorporate “no-go” weather thresholds for nearby thunderstorms, require electronics discipline during ground handling, and brief fire response and evacuation plans before arming the aircraft. These measures reduce the probability and severity of battery-related ignition scenarios.

Protecting people and vehicles during power emergencies (Subpart D; moving vehicles)

If a power anomaly occurs in flight, your preplanned emergency/contingency procedures should prioritize areas clear of people and moving vehicles. Part 107 limits sustained flight over moving vehicles unless you are operating over or within a closed- or restricted-access site; outside such sites, only transit is permitted—no loiter—over vehicles not directly participating in the operation. Category 4 aircraft may have additional allowances if not prohibited by their FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-approved Flight Manual.^[8]

Over people, the aircraft’s eligibility depends on the operation’s category. Category 1 operations require a small unmanned aircraft that weighs 0.55 pounds (250 grams) or less at takeoff and throughout the flight; added components that increase mass may change the category your aircraft qualifies for. Knowing—and respecting—these limits ensures that if a battery issue forces an immediate landing, your operation was already minimizing risk exposure to people and vehicles as required by Subpart D.^[8]

Night factors that interact with batteries (lighting, mass, and category)

At night, anti-collision lighting must be considered in your hazard and preflight assessments, including whether other aircraft can see the light for at least 3 statute miles. Account for night vision adaptation, unlit obstacles, and current/forecast weather that may degrade conspicuity.^[2] If you operate over people at night, you must meet §§ 107.29 and 107.39, and the aircraft must be eligible for the applicable Subpart D category. Manufacturers and pilots should consider the mass of any anti-collision light when determining if the aircraft satisfies Category 2 or 3 performance-based requirements; added lighting can change both the aircraft’s total mass and its category eligibility. These category determinations and restrictions apply equally by day and night.^[4]

Operational implication: ensure your lighting choice both meets night visibility needs and keeps the aircraft within its intended category. A heavier light may disqualify a <0.55 lb platform from Category 1, altering where you can fly people-wise and how you manage emergency descents if a battery anomaly occurs.^[4][8]