Incident: Boeing 737 "Pickle Fork" Cracks Ground Ryanair Planes

Published Date: 2019-11-06

Postmortem Analysis
Timeline 1. The software failure incident involving the grounding of Ryanair Boeing 737s due to cracks in the "pickle fork" structure happened in October 2019 [91851].
System unknown
Responsible Organization 1. The software failure incident involving cracks in the "pickle fork" structure of Boeing 737s was caused by a fault in the design or manufacturing of the aircraft by Boeing [91851].
Impacted Organization 1. Ryanair [91851]
Software Causes unknown
Non-software Causes 1. Cracks in the "pickle fork" structure between the wing and fuselage of the Boeing 737s, leading to grounding of the planes [91851].
Impacts 1. The software failure incident involving cracks in the "pickle fork" structure of Ryanair's Boeing 737s led to the grounding of at least three planes, namely EI-DCL, EI-DAL, and EI-DCJ [91851]. 2. The incident resulted in urgent inspections and checks on affected aircraft globally, with 50 planes being grounded since October 3 [91851]. 3. The grounding of the affected planes impacted Ryanair's operations and fleet availability, although the airline initially stated it did not expect any operational impact [91851]. 4. The incident raised concerns about the safety of the affected aircraft, prompting regulatory authorities to issue directives for immediate inspections of planes with a certain number of flight cycles [91851]. 5. The software failure incident affected not only Ryanair but also other airlines operating Boeing 737-NGs, such as Qantas, Southwest Airlines, and Gol, with a total of 1,000 aircraft being checked and faults discovered in 50 of them [91851].
Preventions 1. Regular and thorough software testing procedures during the development phase could have potentially identified any issues related to the "pickle fork" structure in the Boeing 737NG model before the planes were put into service [91851]. 2. Implementing a more proactive and transparent communication strategy by Ryanair regarding the number of affected planes and the steps being taken to address the issue could have helped prevent the negative impact of the software failure incident [91851]. 3. Following the recommendations and directives issued by aviation regulatory authorities, such as the US Federal Aviation Authority, for timely inspections and maintenance of aircraft could have mitigated the risk of the software failure incident occurring [91851].
Fixes 1. Conducting immediate inspections and checks on all affected Boeing 737-NG aircraft above a certain number of flight cycles to identify and address pickle fork cracks [91851]. 2. Following regulatory requirements for checking older planes within a week and other planes within seven months to ensure safety [91851]. 3. Implementing fast-tracked checking processes for aircraft below the specified flight cycle limit if cracks are discovered in planes below the threshold [91851].
References 1. Internal Ryanair engineering logs [91851] 2. Flight tracking site Flight Aware [91851]

Software Taxonomy of Faults

Category Option Rationale
Recurring unknown The articles do not mention any software failure incidents happening again at either one organization or multiple organizations. Therefore, the information related to the software failure incident in the provided articles does not align with the scenarios described in the question.
Phase (Design/Operation) design, operation (a) The software failure incident related to the design phase can be seen in the case of the pickle fork cracks found in the Boeing 737s. The cracks were first discovered in China, prompting an urgent check by the US Federal Aviation Authority [Article 91851]. This indicates a design flaw or fault in the "pickle fork" structure of the 737NG model, which is a contributing factor introduced during the system development or design phase. (b) The software failure incident related to the operation phase can be observed in the case of how airlines like Qantas and Ryanair had to ground their planes and conduct urgent inspections due to the cracks in the pickle fork structure. This operational failure was a result of the operation and use of the aircraft, leading to the need for immediate checks and repairs to ensure safety [Article 91851].
Boundary (Internal/External) within_system (a) within_system: The software failure incident related to the cracks in the "pickle fork" structure of the Boeing 737s is primarily a within_system failure. The cracks in the pickle fork structure were found internally within the aircraft during inspections, indicating a structural issue within the system itself [91851]. The failure was not caused by external factors but rather by the design and material issues within the aircraft's structure. (b) outside_system: There is no information in the articles suggesting that the software failure incident related to the pickle fork cracks in the Boeing 737s was caused by contributing factors originating from outside the system. The issue of cracks in the pickle fork structure was identified through internal inspections and was not attributed to external influences [91851].
Nature (Human/Non-human) unknown (a) The software failure incident occurring due to non-human actions: - The software failure incident in this case is not directly related to non-human actions but rather to structural issues in the "pickle fork" of the Boeing 737 planes, which is a physical component of the aircraft [91851]. (b) The software failure incident occurring due to human actions: - The software failure incident in this case is not attributed to human actions but rather to structural issues in the "pickle fork" of the Boeing 737 planes, which led to the grounding of several aircraft [91851].
Dimension (Hardware/Software) hardware (a) The software failure incident occurring due to hardware: - The article reports that at least three Ryanair Boeing 737s were grounded due to cracks between the wing and fuselage, specifically in the "pickle fork" structure, which is a hardware component strengthening the connection between the wing and the body of the plane [Article 91851]. (b) The software failure incident occurring due to software: - There is no mention in the article of the software failure incident being caused by contributing factors originating in software. The primary issue discussed in the article is related to hardware failures in the form of cracks in the pickle fork structure of the Boeing 737 planes.
Objective (Malicious/Non-malicious) non-malicious (a) The articles do not mention any malicious software failure incidents related to the grounding of Ryanair Boeing 737s due to cracks in the "pickle fork" structure. There is no indication that the failure was due to contributing factors introduced by humans with the intent to harm the system. (b) The software failure incident related to the grounding of Ryanair Boeing 737s was non-malicious. The issue was attributed to cracks in the "pickle fork" structure, which is a physical structural problem on the aircraft rather than a software-related problem. The failure was not intentional but rather a result of structural issues in the aircraft [91851].
Intent (Poor/Accidental Decisions) unknown The articles do not provide information about a software failure incident related to either poor_decisions or accidental_decisions.
Capability (Incompetence/Accidental) unknown The articles do not mention any software failure incident related to development incompetence or accidental factors. Therefore, the information regarding these specific types of software failure incidents is unknown based on the provided articles.
Duration unknown The software failure incident related to the pickle fork cracks in Ryanair's Boeing 737s is not directly related to a software failure but rather a structural issue with the aircraft. The cracks in the "pickle fork" structure were found in the physical components of the planes, leading to their grounding for inspection and repair. Therefore, the incident does not fall under the categories of permanent or temporary software failure.
Behaviour unknown (a) crash: The software failure incident in the articles does not involve a crash where the system loses state and does not perform any of its intended functions. The issue reported is related to physical cracks in the "pickle fork" structure of Boeing 737 planes, which is a structural concern rather than a software crash [Article 91851]. (b) omission: There is no indication in the articles that the software system omitted to perform its intended functions at any instance. The focus of the articles is on the structural issues with the pickle fork of the Boeing 737 planes [Article 91851]. (c) timing: The software failure incident is not related to the system performing its intended functions too late or too early. The articles do not mention any timing-related issues with the software systems [Article 91851]. (d) value: The software failure incident is not attributed to the system performing its intended functions incorrectly. The issue discussed in the articles pertains to physical cracks in the pickle fork structure of the planes, not software-related errors [Article 91851]. (e) byzantine: The software failure incident does not involve the system behaving erroneously with inconsistent responses and interactions. The focus of the articles is on the structural concerns with the pickle fork of the Boeing 737 planes, not on byzantine behavior of software systems [Article 91851]. (f) other: The behavior of the software failure incident is not applicable in this context as the reported issue is related to physical cracks in the pickle fork structure of Boeing 737 planes, and there is no mention of software-related failures in the articles [Article 91851].

IoT System Layer

Layer Option Rationale
Perception None None
Communication None None
Application None None

Other Details

Category Option Rationale
Consequence property, delay, non-human (property) The consequence of the software failure incident was related to property. The software failure incident involving cracks in the "pickle fork" structure of Boeing 737s led to the grounding of at least three Ryanair planes (registration numbers EI-DCL, EI-DAL, and EI-DCJ) due to the presence of cracks between the wing and fuselage. This issue impacted the availability of these aircraft for operations and required repairs at specific locations like the Southern California Logistics Airport in Victorville, California, and Stansted airport in London [Article 91851].
Domain transportation The software failure incident reported in the news article [91851] is related to the transportation industry. Specifically, the incident involves the grounding of Ryanair Boeing 737s due to cracks in the "pickle fork" structure, which is a critical component connecting the wing and fuselage of the aircraft. This issue has led to the urgent grounding of 50 planes globally, affecting airlines like Ryanair, Qantas, Southwest, and others. The grounding of these aircraft is a safety measure to address the structural faults identified in the pickle fork, which is essential for the safe operation of the aircraft [91851].

Sources

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