In the course of the safety investigation concerning the accident involving the drone SUI-9903 on 9 May 2019 near the city of Zurich (ZH), the Swiss Transportation Safety Investigation Board STSB identified a safety deficit and issued Safety Recommendation SR No. 587 in its final report No. 2390.
SR 588: Compliance of drone operators with Service Bulletins on flight-critical components or their software
| Status | closed |
|---|---|
| STSB assessment | |
| status of implementation | not implemented |
| FOCA opinion | |
| Safety deficit | agreement |
| Safety recommendation | partial agreement |
| next update due | - |
Safety recommendation
Ensure that operators of drones comply with Service Bulletins on flight-critical components or their software
Safety deficit
Amendment instructions, controlled flight abortion and sensor technology
Ensure that operators of drones comply with Service Bulletins on flight-critical components or their software
The Federal Office of Civil Aviation (FOCA) should ensure that operators of drones that are used in scenarios with higher risk – in particular for flights beyond the visual line of sight (BVLOS) over populated areas – comply with Service Bulletins on flight-critical components or their software.
Amendment instructions, controlled flight abortion and sensor technology
About one minute after take-off at the University of Zurich (UZH) Irchel, the M2 V9 drone automatically triggered the flight termination system (FTS) and initiated an emergency descent with a parachute. After ejecting the parachute, the connecting rope broke and the drone hit the forest floor without deceleration and was de-stroyed.
As the investigation showed, the applied firmware of the flight controller based on the software version ArduCopter 3.5.0-rc5 was only capable of using two of the three available inertial measurement units (IMU) for the flight control of the drone. As a result, the flight controller's software lacked the ability, known as resilience, not to fail completely in the event of malfunctions or the failure of individual components, but to maintain control of the drone.
Only from software version 3.6.12 onwards was it possible to achieve this resili-ence with the corresponding configuration of the safety-critical parameter ("EK2_IMU_MASK = 7"), as published in a discussion forum of the flight controller manufacturer as Service Bulletin SB 0000002.In the case of the accident involving the largely identical drone SUI-9909 on 25 January 2019 (cf. summary report), the FTS was also immediately triggered due to a loss of the GPS signal. As the investigation showed, the drone's flight attitude was still stable at this time and thus a landing under engine power, either manually controlled on sight or autonomously, would not have been fundamentally impossible.
When operating under extreme climatic conditions, corresponding flight-critical parameters such as ambient temperature and humidity are not included in practice. This would allow a flight mission to be aborted early or not carried out at all under certain conditions.
Implementation and FOCA opinion
15.11.2023 | Response on the status of implementation
29.09.2023 | Initial (and conclusive) statement
09.05.2019 | Unfall mit SUI-9903, bei Zürich (ZH)
In its letter dated 15 November 2023, the Swiss Transportation Safety Investigation Board STSB informs the Federal Office of Civil Aviation FOCA that it has assessed SE No. 588 as "implemented".
Das Bundesamt für Zivilluftfahrt (BAZL) ist mit der Sicherheitsempfehlung (SE) Nr. 588 teilweise einverstanden.
Das BAZL ist nicht die zuständige Behörde für die Überwachung der Regelkonformität bezüglich Konstruktion (design) und Aufrechterhaltung der Lufttüchtigkeit (continuous airworthiness) eines unbemanntenLuftfahrzeuges. Die Rollen und Verantwortlichkeiten der zuständigen Behörden werden in derDurchführungsverordnung (EU) 2019/947, bzw. den Applicable Means of Compliance (AMC) 1, Art. 11,Abs. 1.5 (f), festgelegt:
According to Regulation (EU) 2018/1139 (the EASA ‘Basic Regulation’), EASA is the authority competent in the European Union to verify compliance of the UAS design and its components with the applicable rules, while the authority that is designated by the Member State is competent to verify compliance with the operational requirements and compliance of the personnel’s competency with those rules
Dementsprechend sieht das BAZL die Agentur der Europäischen Union für Flugsicherheit EASA als verantwortlich für die Umsetzung der Sicherheitsempfehlungan. Zudem wird beim Betrieb von SAIL II-Bewilligungen die Verantwortung zur Aufrechterhaltungder Lufttüchtigkeit, mittels Operational Safety Objectives (OSO) auf den Betreiber des unbemanntenLuftfahrzeugs übertragen.
Mit der vorliegenden Sicherheitsempfehlung anerkennt das BAZL, dass es sich stärker als bisher dafür einsetzt, dass die Betreiber von unbemannten Luftfahrzeugen die Service Bulletins für flugkritische Komponenten oder deren Software einhalten. Dies wird bei der Überprüfung von Betriebshandbüchern oder durch Audits sichergestellt.
Das BAZL erachtet die Sicherheitsempfehlung Nr. 588 hiermit als vollständig umgesetzt und abgeschlossen.
Last modification 23.01.2025
Contact
Federal Office of Civil Aviation FOCA
Postal Address:
Federal Office ofCivil Aviation
3003 Bern
Switzerland
Location:
Papiermühlestrasse 172
3063 Ittigen
Switchboard:
Monday-Friday 8.30–11.30 and 14.00–16.00
Tel: +41 58 465 80 39
Fax: +41 58 465 80 32
Drones:
1. Please consult the corresponding web pages first.
2. Clarify your doubts on the “FAQ” page.
3. If you cannot find the information you are looking for, please contact us by e-mail. We will not answer any questions by phone.
Passengerrights:
Tel: +41 58 465 95 96
(Weekdays from 2.00 to 4.00 pm)
Airworthiness (technical questions):
Tel: +41 58 465 67 89
Fax: +41 58 465 80 32
Swiss Aircraft Registry:
Tel: +41 58 465 35 35
Fax: +41 58 465 80 32
Pilote Licences:
Tel: +41 58 463 54 56 (working days 9.00-11.30am)
Helicopter:
Tel: +41 58 464 62 93
Fax: +41 58 465 80 32
Maintenance Personnel Licences:
Tel: +41 58 465 05 57
Fax: +41 58 465 80 32
Aeromedical Section (AMS):
Tel: +41 58 465 91 65
Fax: +41 58 465 90 63
Diplomatic Clearances:
Tel: +41 58 465 91 77
Fax: +41 58 465 80 60
For the Media (for journalists only):
Tel: +41 58 464 23 35 (de)
Tel: +41 58 464 72 87 (fr)
Readiness on weekends
Tel: +41 58 465 31 31