Overview
ISO 24355:2023 - Flight control system for civil small and light multicopter unmanned aircraft system (UAS) - General requirements - defines the composition, functional and performance requirements for flight control systems (FCS) used on civil multicopter unmanned aircraft (UA) with a maximum take-off mass (MTOM) ≤ 25 kg. The standard targets UAS at levels I–IV (per ISO 21895) and explicitly excludes fully autonomous flights. ISO 24355:2023 is applicable to design and manufacture of FCS units and subsystems.
Key topics and technical requirements
- System composition: Defines typical FCS elements - flight control unit, navigation unit, fault diagnosis/management, power management, flight planning, flight recorder and interfaces (including communication with an RPS).
- Flight control functions:
- Angular velocity (rate) control, attitude control, velocity control and position control (when appropriate navigation sensors are fitted).
- Requirements to reach target values within allowable time and to resist disturbances from external forces.
- Navigation unit:
- Core functions: compute latitude/longitude, altitude, ground speed, heading, IMU-derived attitude/rate/acceleration, barometric altitude and GNSS positioning.
- Sensor calibration, fault diagnosis and optional features such as AGL sensing, relative positioning, geofencing interfacing, sensor redundancy management, covariance/accuracy estimation and environmental monitoring.
- Flight management:
- Mode switching (manual, semi-automatic, automatic), ground/air detection, remaining endurance reporting, component fault detection, envelope protections, and mission guidance including waypoint sequencing (2D/3D/4D).
- Take-off and landing management: pre-take-off checks, home-point recording, environmental monitoring, safe-landing triggers and configurable landing speeds.
- Flight recorder: mandated logging of navigation data, control modes, remote-control inputs, system faults/warnings and flight status at manufacturer-specified frequency.
- Safety, emergency management and interfaces: fault handling, protective measures and RPS/UTM interactions.
- Performance & support: manufacturer responsibilities for system accuracy, flight quality, navigation performance, firmware/version management, user configuration/tuning support, user manuals, identification, packaging, transport and storage.
Applications and users
ISO 24355:2023 is intended for:
- UAS and multicopter manufacturers designing FCS hardware and software
- System integrators and avionics suppliers
- Test labs and certification bodies assessing compliance for small/light UAS (MTOM ≤ 25 kg)
- Fleet operators and service providers implementing safe take-off/landing and mission management workflows
Practical uses include FCS design specification, supplier contracts, verification test plans, and operational procedures for civil multicopter UAS.
Related standards
Keywords: ISO 24355:2023, flight control system, multicopter UAS, FCS, navigation unit, flight recorder, MTOM ≤ 25 kg, unmanned aircraft system.