UA.V.F.K6: Preflight inspection for night operations.

ACS Area V — Operations Task F: Maintenance and Inspection Procedures References: A-7

Key Concepts

Define “Night,” Plan Lighting, and Verify Night Equipment

Know when your operation is legally “at night” versus “civil twilight.” Night is the time between the end of evening civil twilight and the beginning of morning civil twilight. In the continental U.S., evening civil twilight runs from sunset until 30 minutes after sunset; morning civil twilight is 30 minutes prior to sunrise until sunrise. During civil twilight, the small unmanned aircraft must be equipped with anti-collision lighting visible for at least 3 statute miles. For operations at night proper, comply with § 107.29. Preflight at night means confirming that anti-collision lighting is installed, secure, and functioning to meet visibility requirements before departure, and that your time-of-day determination is based on published sources such as The Air Almanac (converted to local time).^[6]

Night operations also demand honest crew self-assessment. Conditions such as illness, medication that impairs alertness, or a debilitating physical condition can prevent the remote PICRemote Pilot in CommandCloseThe certificated remote pilot responsible for the Part 107 operation., manipulator of controls, or visual observer from maintaining situational awareness. If there is a hearing or speaking impairment, the remote PICRemote Pilot in CommandCloseThe certificated remote pilot responsible for the Part 107 operation. must implement an effective alternate means of communication (e.g., nonverbal methods) before flight.^[6]

Required Preflight Inspection and Maintenance Status

Your regulatory duty is twofold: ensure the aircraft is in a condition for safe operation (§ 107.15) and perform a preflight inspection prior to each flight (§ 107.49). Practically, this means using the manufacturer’s inspection procedures when available, or an operator-developed procedure, to examine the aircraft for equipment damage or malfunctions before every launch. All required maintenance should be completed before each flight; if you or maintenance personnel cannot repair or overhaul a component back to its safe operational specification, replace it with one that is in a condition for safe operation. Consider creating a scalable inspection program tailored to your aircraft, aligned with manufacturer guidance or industry best practices.^[3][1]

During the inspection, actively look for conditions that would ground the aircraft at night just as in the day, with extra attention to items that can be harder to detect in low light. Examples that warrant further inspection and likely corrective action include:

• Structural or skin cracking (possible hidden damage, compromised integrity)
• Delamination of bonded surfaces
• Liquid or gel leakage (fire risk and performance impacts)^[5]

If Operating Over People at Night: Verify Category, Labeling, and Limitations

Night doesn’t change which category (1–4) your operation uses; the categories and their restrictions for operations over people are time-of-day neutral. The remote pilot is responsible for confirming the aircraft is in the correct category for the mission, ensuring it is properly labeled, and verifying it is listed on an FAAFederal Aviation AdministrationCloseThe U.S. aviation regulator responsible for Part 107 rules, airspace, and pilot certification processes.-accepted Declaration of Compliance (DOCDeclaration of ComplianceCloseManufacturer compliance document that matters for some Operations Over People categories.). If the aircraft is eligible for operations over people at night, you may operate over human beings at night pursuant to §§ 107.29 and 107.39. Note that the mass of your anti-collision light may affect a manufacturer’s category qualification analysis; ensure your configuration matches the aircraft’s eligibility.^[8]

Before any Category 2 or 3 operation, check the Category label. If it is damaged, destroyed, or missing, the remote PICRemote Pilot in CommandCloseThe certificated remote pilot responsible for the Part 107 operation. must affix a legible, prominent English label that remains on the aircraft for the duration of the operation and correctly identifies the eligible categories before conducting operations over human beings.^[2]

For Category 4, confirm the aircraft has an airworthiness certificate issued under part 21, you will operate in accordance with the approved Flight Manual (and any Administrator-specified limitations), and that maintenance, preventive maintenance, alterations, or inspections are performed per § 107.140(c)(1). Category 4 also prohibits sustained flight over open-air assemblies of human beings unless the operation meets § 89.110 or § 89.115(a).^[2] If operating in Category 1, remember the takeoff weight threshold is 0.55 pounds (250 grams) or less throughout the flight, a detail you should confirm during preflight configuration checks.^[7]

Night Weather and Hazard Considerations

Night preflight includes conservative weather evaluation. Thunderstorms and lightning present serious hazards; a common safety practice is to avoid electrical storms within 10 nautical miles, recognizing lightning can travel significant distances beyond the visible storm. While this reference comes from rotorcraft fueling guidance, the hazard principle applies to small UASSmall Unmanned Aircraft SystemCloseA small drone plus the control and communication links used to operate it. operations at night as well.^[4]