ISO 5332:2023

Overview

ISO 5332:2023 - Civil small and light unmanned aircraft systems (UAS) under low‑pressure conditions - Test methods - specifies standardized environmental test methods to determine the operational capability of civil small and light UAS when exposed to low‑air‑pressure (high‑altitude) conditions. It applies to UAS in MTOM levels II through V as defined in ISO 21895 and defines chamber conditions, procedures, acceptance checks and reporting requirements for functional performance at reduced pressure and temperature combinations.

Key topics and technical requirements

• Test scope: Functional performance verification of small and light civil UAS at low air pressure; certain functional checks are performed inside a test chamber (Annex A).
• Representative test points: Example low‑pressure test conditions include:
  • –46 °C at 40 kPa (≈ 7 150 m)
  • –19 °C at 70 kPa (≈ 3 000 m)
  • –32 °C at 55 kPa (≈ 4 850 m) (Also includes high‑temperature/low‑pressure variants; pressures can be calculated per referenced formula.)
• Allowed tolerances: temperature ±2 °C; air pressure ±5 %; relative humidity ±3 %.
• Rates of change: temperature change ≤ 3 °C/min; pressure change ≤ 4.8 kPa/min.
• Preconditioning: temperature stabilization times based on UAS mass (≤1.5 kg: 1 h; ≤15 kg: 2 h; ≤150 kg: 4 h), with guidance referencing IEC 60068‑2‑39.
• Test chamber requirements: valid calibration, ability to maintain specified conditions, contamination control for chamber intake air, and continuous monitoring of temperature and pressure.
• Procedures: pretest functional inspection at standard atmosphere (15–35 °C; 84–107 kPa; RH ≤85 %), conditioning (sequence guidance), recovery to standard conditions, and post‑test inspection and reporting.
• Failure handling: rules for interruption, restart, replacement or repair of test articles.
• Documentation: minimum test report contents include model/serial, standards used, methods, results, deviations and date.

Applications and who uses it

• UAS manufacturers conducting environmental qualification for high‑altitude operation.
• Independent test laboratories and certification bodies performing conformity and performance assessments.
• R&D and engineering teams validating flight control, sensors, data storage, camera systems, VTOL takeoff/landing, obstacle avoidance and other functional items under reduced pressure.
• Operators planning missions in mountainous or high‑altitude regions who need documented evidence of operational suitability.

Related standards

• ISO 21895 - MTOM level definitions for small and light UAS (referenced for applicability).
• ISO 21384‑4 - UAS vocabulary and terms referenced.
• IEC 60068‑2‑39 and IEC 60721‑2‑3 - referenced for temperature stabilization and atmospheric calculations.

Keywords: ISO 5332:2023, UAS test methods, low‑air‑pressure testing, unmanned aircraft systems, environmental testing, high‑altitude UAS.