Yazılım Yoğun Uçuş Kontrol Sistemlerinde Sertifikasyon Güvencesi ve Operasyonel Öğrenme: Airbus A320 ELAC Arızaları Üzerine Çok Boyutlu Bir Analiz

Öz

Yazılım ağırlıklı “fly-by-wire” uçuş kontrol sistemleri, yüksek sertifikasyon ve geliştirme güvencesi süreçlerinden geçirilerek tasarlansa da, nadir çevresel etkiler, yazılım sınır koşulları ve operasyonel etkileşimler bazı emniyet risklerinin ancak operasyon sırasında ortaya çıkmasına neden olabilmektedir. Bu çerçevede bu çalışma, “Airbus A320 Elevator Aileron Computer (ELAC)” sistemi arızalarını detaylı olarak ele almakta ve tasarım güvencesi, operasyonel emniyet performansı ile sürekli uçuşa elverişlilik arasındaki ilişkiyi incelemektedir. Analiz, 2025 yılında ABD’de meydana gelen spesifik bir hava aracı emniyeti olayının hemen ardından EASA tarafından acil kodlu bir uçuşa elverişlilik direktifinin (EASA AD No. 2025-0268-E) yayımlanması ve bu olaya ilişkin Avrupa Birliği Havacılık Emniyeti Ajansı (EASA) ile ABD Federal Havacılık İdaresi (FAA) tarafından gerçekleştirilen müteakip düzenleyici faaliyetlerden hareketle yapılandırılmıştır. Çalışma, birbirini tamamlayan üç analitik boyutu bir araya getirmekte olup bunlar sırasıyla Airbus “fly-by-wire” anomalilerine ilişkin “NASA Havacılık Emniyeti Raporlama Sistemi (ASRS)” raporlarının yapılandırılmış değerlendirmesi, söz konusu acil uçuşa elverişlilik direktifini tetikleyen olayın vaka temelli analizi ve bahse konu olguya yönelik Sistem Teorik Süreç Analizi (STPA) ile İsviçre Peyniri (Swiss Cheese) modeli kullanılarak gerçekleştirilen sistem emniyeti değerlendirmesidir. Bulgular, hava aracı sertifikasyonunun emniyetin nihai ve değişmez kanıtı olarak değil, operasyonel veriler, olay incelemeleri, düzeltici faaliyetler ve tasarım iyileştirmeleriyle sürekli olarak beslenen uçuşa elverişlilik yönetimi döngüsünün temel bir unsuru olarak görülmesi gerektiğini göstermektedir. Sonuç olarak, çalışma ELAC vakası üzerinden yazılım yoğun aviyonik sistemlerde sürdürülebilir emniyetin ancak tasarım varsayımlarının operasyonel öğrenme yoluyla düzenli biçimde sınanması ve gerektiğinde güncellenmesiyle sağlanabileceğini ileri sürmektedir.

Anahtar Kelimeler

• Airbus a320
• Fly-by-wire
• Uçuş kontrol sistemleri
• NASA ASRS
• STPA
• İsviçre peyniri modeli

Etik Beyan

Bu araştırmada hayvanlar ve insanlar üzerinde herhangi bir çalışma yapılmadığı için etik kurul onayı alınmamıştır.

Certification Assurance and Operational Learning in Software-Intensive Flight Control Systems: A Multidimensional Analysis of Airbus A320 ELAC Failures

Öz

Although software-intensive fly-by-wire flight control systems are designed through rigorous certification and development assurance processes, rare environmental effects, software boundary conditions, and operational interactions may cause certain safety risks to emerge only during service. Within this context, this study addresses failures of the Airbus A320 Elevator Aileron Computer (ELAC) system and examines the relationship between design assurance, operational safety performance, and continuing airworthiness. The analysis is structured around the issuance of an emergency airworthiness directive by EASA (EASA AD No. 2025-0268-E) immediately after a specific aircraft safety event that occurred in the United States in 2025, as well as the subsequent regulatory actions undertaken by the European Union Aviation Safety Agency (EASA) and the U.S. Federal Aviation Administration (FAA). The study integrates three complementary analytical dimensions: a statistical analysis of NASA Aviation Safety Reporting System (ASRS) reports related to Airbus fly-by-wire anomalies; an event-based examination of the systemic failure that triggered the relevant emergency airworthiness directive; and a system safety assessment of these anomalies using Systems-Theoretic Process Analysis (STPA) and the Swiss Cheese Model. The findings indicate that aircraft certification should not be regarded as the final and immutable proof of safety, but rather as a fundamental component of a continuing airworthiness management cycle that is continuously informed by operational data, event investigations, corrective actions, and design improvements. Consequently, through the case of ELAC systemic failures, the study argues that sustainable safety in software-intensive avionics systems can only be achieved by regularly testing and, when necessary, updating design assumptions through operational learning.

Anahtar Kelimeler

• Airbus a320
• Fly-by-wire
• Flight control systems
• NASA ASRS
• STPA
• Swiss cheese model

Kaynakça

1. Airbus. (2023). A318/A319/A320/A321 flight crew operating manual (FCOM): ATA 27 flight controls. Airbus S.A.S.
2. Airbus. (2025, November 28). Airbus update on A320 Family precautionary fleet action. Airbus S.A.S.
3. Airbus. (2026). A318/A319/A320/A321 airplane flight manual (AFM): ABN-27 flight controls. Airbus S.A.S.
4. Castilho, D. S., Urbina, L. M. S., & de Andrade, D. (2018). STPA for continuous controls: A flight-testing study of aircraft crosswind takeoffs. Safety Science, 108.
5. De Florio, F. (2016). Airworthiness (Third Edition): An Introduction to Aircraft Certification and Operations. Chapter 5 - Type Certification, Pages 85-122.
6. Downer, J. (2010). Trust and technology: The social foundations of aviation regulation. The British Journal of Sociology, 61, 83–106.
7. EASA. (2023). European Union Aviation Safety Agency. Easy Access Rules for Large Aeroplanes (Certification specifications for large aeroplanes / CS-25).
8. EASA. (2025a). European Union Aviation Safety Agency. Emergency airworthiness directive AD No. 2025-0268-E: Flight controls—Elevator aileron computer—Replacement.

9. EASA. (2025b). European Union Aviation Safety Agency. Easy Access Rules for Initial Airworthiness and Environmental Protection (EU Regulation No 748/2012 / EASA Part-21).
10. EASA. (2026). European Union Aviation Safety Agency. Airworthiness directive, AD No. 2026-0134: ATA 27 – Flight Controls – Elevator Aileron Computer – Replacement.
11. FAA. (2011). Federal Aviation Administration. AC 20-174: Development of civil aircraft and systems.
12. FAA. (2017). Federal Aviation Administration. AC 20-175: Airborne Software Development Assurance Using EUROCAE ED-12 and RTCA DO-178.
13. FAA. (2020). Federal Aviation Administration. Return to Service of the Boeing 737 MAX Aircraft: Summary of the FAA’s Review of the Boeing 737 MAX.
14. FAA. (2025). Federal Aviation Administration. 14 CFR Part 21 - Certifıcation Procedures for Products and Articles (FAR Part-21).
15. FAA. (2026a). Federal Aviation Administration. 14 CFR Part 25 - Airworthiness Standards: Transport Category Airplanes (FAR Part-25).
16. FAA. (2026b). Federal Aviation Administration. Airworthiness directives; Airbus SAS airplanes. Federal Register, 91, 199–202.
17. Knight, J. C. (2002). Safety critical systems: Challenges and directions. In Proceedings of the 24th International Conference on Software Engineering, Orlando, FL, United States, May 19–25, 2002.
18. Kornecki, A., & Zalewski, J. (2003). Assessment of Software Development Tools For Safety -Critical Real-Time Systems. IFAC Programmable Devices and Systems.
19. Leveson, N. (2010). Applying systems thinking to analyze and learn from events. Safety Science.
20. Leveson, N., & Thomas, J. P. (2018). STAMP handbook.
21. Lewis, E. (2025). Airbus A320 ELACs explained: How a software glitch caused a JetBlue pitch-down and forced urgent inspections. Aerospace Global News.
22. NASA. (2026a). National Aeronautics and Space Administration. Aviation Safety Reporting System overview.
23. NASA. (2026b). National Aeronautics and Space Administration. ASRS Database Online.
24. NTSB. (2019). National Transportation Safety Board. Safety Recommendation Report: Assumptions Used in the Safety Assessment Process and the Effects of Multiple Alerts and Indications on Pilot Performance.
25. NTSB. (2026). National Transportation Safety Board. ENG26LA004 preliminary report: JetBlue Flight 1230 event.
26. Nicolin, I., & Nicolin, B. A. (2019). The fly-by-wire system. Incas Bulletin, Volume 11, Issue 4, 2019, pp. 217 – 222.
27. Orban, A. (2025). The Airbus A320 flight-control crisis: What happened and how it was quickly resolved. Aviation24.
28. Reason, J. (1990). Human error. Cambridge University Press.
29. RTCA. (2011). DO-178C: Software considerations in airborne systems and equipment certification.
30. SAE International. (2010). ARP4754A: Guidelines for development of civil aircraft and systems.
31. Sgobba, T. (2019). B-737 MAX and the crash of the regulatory system. Journal of Space Safety Engineering Volume 6, Issue 4, December 2019, Pages 299-303.
32. Underwood, P., & Waterson, P. (2014). Systems thinking, the Swiss Cheese Model and accident analysis: A comparative systemic analysis of the Grayrigg train derailment using the ATSB, AcciMap and STAMP models. Accident Analysis & Prevention, 68, 75–94.