Incident: Ariane 5 Rocket Launch Failure Due to Integer Overflow Bug

Published Date: 2015-05-14

Postmortem Analysis
Timeline 1. The software failure incident with the Ariane 5 rocket happened on June 4, 1996 as mentioned in [Article 36307]. 2. The software failure incident with the Ariane 5 rocket happened on June 4, 1996 as mentioned in [Article 36305].
System 1. Software system of the Ariane 5 rocket [Article 36307] 2. Unit of control managing engine power distribution in Boeing 787 [Article 36307]
Responsible Organization 1. The software failure incident in the Ariane 5 rocket launch was caused by a simple bug in the software, specifically an integer overflow, which led to incorrect calculations due to being overwhelmed by numbers longer than it could handle. This incident was attributed to a process left over from the previous generation software (Ariane 4) that captured an unexpected speed measurement in the new vehicle, causing the software of Ariane 5 to malfunction [36307]. 2. The potential software failure incident in the Boeing 787 was related to a control unit managing engine power distribution that could enter a fail-safe mode and shut down the engines if left on for more than 284 days. This issue was due to a counter in the control unit software overflowing after the specific time period, potentially leading to sudden engine shutdowns during flight [36307].
Impacted Organization 1. The European Space Agency (ESA) was impacted by the software failure incident involving the Ariane 5 rocket launch failure, resulting in a loss of $370 million [36307, 36305]. 2. NASA was impacted by a similar software failure incident that led to the loss of contact with the Deep Impact spacecraft in 2013 [36307].
Software Causes 1. The failure incident of the Ariane 5 rocket in 1996 was caused by a simple bug in the software, specifically an integer overflow issue due to the software being overwhelmed by numbers longer than it could handle [36307]. 2. The potential problem with the Boeing 787 was also related to a software issue, where the control unit managing engine power distribution could enter a fail-safe mode and shut down the engines if left on for more than 248 days, which corresponds to the maximum positive value that can be stored in a 32-bit processor [36307]. 3. The incident with the Patriot missile defense system during the Gulf War in 1991 was caused by an overflow error in the software, leading to the system failing to track the trajectory of an incoming Scud missile, resulting in casualties [36305].
Non-software Causes 1. The failure incident of the Ariane 5 rocket was not caused by a mechanical failure or sabotage but by a simple bug in the software due to an overflow of integers [36307]. 2. The incident involving the Patriot missile defense system during the Gulf War was caused by an overflow error that led to the system tracking the missile at a distance from the actual target, resulting in casualties [36305].
Impacts 1. The software failure incident involving the Ariane 5 rocket in 1996 resulted in a catastrophic explosion 39 seconds after launch, causing a loss estimated at US$370 million [36307, 36305]. 2. The incident was caused by a simple bug in the software, specifically an integer overflow error, which led to incorrect calculations when the software became overloaded with numbers longer than it could handle [36307, 36305]. 3. Similar errors caused a series of incidents in the past, including the loss of contact with the Deep Impact spacecraft by NASA in 2013 [36307]. 4. The potential impact of a similar software issue was highlighted in a Boeing 787, where the control unit managing engine power distribution could enter a fail-safe mode if left on for more than 284 days, potentially leading to engine shutdown during flight [36307, 36305]. 5. The incident with the Ariane 5 rocket and other software failures demonstrate the critical importance of addressing and mitigating software bugs and limitations, especially in systems that rely on precise calculations and operations [36307, 36305].
Preventions 1. Proper testing and validation of the software to identify and address potential integer overflow issues could have prevented the software failure incident [36307, 36305]. 2. Implementing software design practices that account for potential limitations in storing large numbers, such as using appropriate data types and ensuring compatibility with system specifications, could have helped prevent the incident [36307, 36305]. 3. Regular software updates and maintenance to address known issues and adapt to changing technological requirements could have mitigated the risk of software failures related to integer overflow [36307, 36305]. 4. Conducting thorough risk assessments and scenario planning to anticipate and prepare for potential software failures, especially those related to numerical calculations, could have helped prevent the incident [36307, 36305].
Fixes 1. Implementing proper software testing procedures to identify and address integer overflow issues before deployment [36307, 36305]. 2. Updating the software to handle larger numbers and prevent integer overflow situations [36307, 36305]. 3. Ensuring that software systems are regularly maintained and updated to prevent future incidents related to integer overflow [36307, 36305]. 4. Conducting thorough risk assessments and scenario planning to anticipate and mitigate potential software failures due to integer overflow [36307, 36305]. 5. Enhancing software development practices to include better error handling mechanisms for handling large numbers and preventing system failures [36307, 36305].
References 1. The software failure incident information is gathered from the investigation of the European Space Agency's Ariane 5 rocket launch failure in 1996, which was caused by a software bug [36307, 36305]. 2. The articles also mention incidents like the loss of contact with the NASA Deep Impact spacecraft in 2013 due to software reaching an integer limit [36307, 36305]. 3. Information is sourced from the potential software issue with a Boeing 787 aircraft, where the control unit managing engine power distribution could shut down the engines if left on for more than 248 days [36307, 36305]. 4. The articles refer to historical software failures like the Y2K bug and the incident with the Patriot missile defense system during the Gulf War [36307, 36305]. 5. The articles discuss the potential future software issue related to the year 2038 problem, where the number of seconds since January 1, 1970, may exceed the maximum value that can be stored in many computer systems [36307, 36305].

Software Taxonomy of Faults

Category Option Rationale
Recurring one_organization, multiple_organization (a) The software failure incident having happened again at one_organization: The incident of a software failure due to an integer overflow causing the Ariane 5 rocket launch failure in 1996 is mentioned in both articles [36307, 36305]. This incident was caused by a simple bug in the software that made incorrect calculations when overloaded with numbers longer than it could handle. The same type of error was also responsible for incidents like the loss of contact with the Deep Impact spacecraft by NASA in 2013. (b) The software failure incident having happened again at multiple_organization: The articles mention that similar incidents related to integer overflow causing software failures have occurred in other organizations or contexts. For example, the article mentions a potential issue with a Boeing 787 where the control unit managing engine power distribution could enter a fail-safe mode if left on for more than 284 days, potentially causing the engines to shut down mid-flight [36307]. This highlights how integer overflow issues can impact various systems beyond just the Ariane 5 rocket incident.
Phase (Design/Operation) design (a) The software failure incident related to the development phases: The incident involving the Ariane 5 rocket launch failure was caused by a software bug that occurred during the design phase. The failure was attributed to a simple bug in the software that made incorrect calculations when overloaded with numbers longer than it could handle. Specifically, the software from the previous generation, Ariane 4, left a process that captured an unexpected speed measurement in the new vehicle, Ariane 5, which the software couldn't handle, leading to a sequence of self-destruction and the tragic explosion of the rocket [36307]. (b) The software failure incident related to the operation phases: There is no specific information provided in the articles about a software failure incident directly related to the operation phases.
Boundary (Internal/External) within_system (a) The software failure incident related to the Ariane 5 rocket launch in 1996 was within the system. The incident was caused by a simple bug in the software that resulted in incorrect calculations due to an integer overflow issue. The software was unable to handle a large number, leading to a sequence of self-destruction and the tragic explosion of the rocket [36307, 36305].
Nature (Human/Non-human) non-human_actions (a) The software failure incident occurring due to non-human actions: The software failure incident with the Ariane 5 rocket launch in 1996 was caused by a simple bug in the software, specifically an integer overflow. The software became overwhelmed with numbers longer than it could handle, leading to incorrect calculations and ultimately the tragic explosion of the rocket [36307, 36305]. (b) The software failure incident occurring due to human actions: There is no specific mention in the provided articles about a software failure incident directly caused by human actions. The incidents discussed, such as the Ariane 5 rocket launch failure and the potential issue with the Boeing 787, were primarily attributed to non-human factors like software bugs and integer overflows.
Dimension (Hardware/Software) hardware, software (a) The software failure incident occurring due to hardware: - The incident involving the Ariane 5 rocket failure was not caused by a hardware failure but rather by a simple bug in the software. The disaster was attributed to a software bug that made incorrect calculations when overloaded with numbers longer than it could handle [Article 36307]. - The incident with the Boeing 787 potentially facing a similar problem was related to the unit of control managing engine power distribution automatically entering a fail-safe mode if left on for more than 284 days, which could lead to engines shutting down mid-flight. This issue was due to a specific counter in the software overflowing after the specified time period, which is a hardware-related limitation [Article 36307]. (b) The software failure incident occurring due to software: - The failure of the Ariane 5 rocket launch was specifically attributed to a software bug that caused incorrect calculations due to an overflow of integers, leading to a sequence of self-destruction and the tragic outcome of the launch [Article 36307]. - The incident involving the Deep Impact spacecraft losing contact with NASA in 2013 was suspected to be due to the software reaching an integer limit, showcasing another example of software failure related to numerical overflow [Article 36307]. - The article also mentions the Y2K bug as a software-related failure, where systems storing years with only the last two digits faced confusion and potential malfunctions due to the change from 1999 to 2000 [Article 36305].
Objective (Malicious/Non-malicious) non-malicious (a) The software failure incident related to the Ariane 5 rocket launch on June 4, 1996, was non-malicious. The incident was caused by a simple bug in the software, specifically an integer overflow, which led to incorrect calculations due to the system being overloaded with numbers longer than it could handle. This non-malicious software bug resulted in the tragic explosion of the rocket, causing significant financial loss [36307, 36305].
Intent (Poor/Accidental Decisions) accidental_decisions From the provided articles, the software failure incident related to the Ariane 5 rocket launch failure was primarily due to accidental_decisions. The incident was caused by a simple bug in the software that resulted in incorrect calculations when the system became overloaded with numbers longer than it could handle. This bug was not a result of poor decisions but rather an unintended consequence of the software being overwhelmed by the input data, leading to the tragic failure of the launch [36307, 36305].
Capability (Incompetence/Accidental) development_incompetence (a) The software failure incident occurring due to development incompetence: - The failure of the Ariane 5 rocket launch in 1996 was caused by a simple bug in the software, specifically an integer overflow issue. The software was unable to handle a large number, leading to a sequence of self-destruction and the tragic explosion of the rocket [36307]. - The incident involving the Patriot missile defense system during the Gulf War in 1991 was also attributed to a software error related to an overflow issue. The system failed to track the incoming Scud missile accurately, resulting in it missing the target and causing casualties [36305]. (b) The software failure incident occurring accidentally: - The incident with the Boeing 787 potential problem highlighted in the article was related to a control unit that could enter a fail-safe mode, shutting down the engines if left on for more than 248 days. This issue was not intentional but a result of a counter in the software overflowing after a specific period of time, potentially leading to engine shutdown during flight [36307].
Duration permanent, temporary (a) The software failure incident related to the Ariane 5 rocket launch on June 4, 1996, was a permanent failure. The incident was caused by a simple bug in the software that made incorrect calculations due to an integer overflow, leading to the tragic explosion of the rocket shortly after launch [36307, 36305]. (b) The software failure incident related to the Boeing 787 potentially suffering a similar issue with the engine control unit was a temporary failure. The unit could enter a fail-safe mode and shut down the engines if left on for more than 284 days, which could hypothetically lead to sudden engine shutdown during flight. This issue was highlighted in early May, and the FAA and Boeing declined to comment on the matter for the article [36307].
Behaviour crash, omission, value (a) crash: The software failure incident described in the articles can be categorized as a crash. In the case of the Ariane 5 rocket launch failure, the software bug caused the rocket to crash and explode 39 seconds after liftoff, resulting in a catastrophic failure [36307, 36305]. (b) omission: The software failure incident can also be categorized as an omission. The incident occurred because the software omitted to perform its intended functions correctly due to a simple bug that caused incorrect calculations when overloaded with numbers longer than it could handle, leading to the failure of the rocket launch [36307, 36305]. (c) timing: The software failure incident is not directly related to a timing failure where the system performs its intended functions but at the wrong time. Instead, the failure was due to incorrect calculations leading to a crash [36307, 36305]. (d) value: The software failure incident is primarily related to a value failure. The incident was caused by an integer overflow error, where the software was unable to handle numbers that were too large for the system to store, resulting in incorrect calculations and the subsequent failure of the rocket launch [36307, 36305]. (e) byzantine: The software failure incident is not related to a byzantine failure where the system behaves erroneously with inconsistent responses and interactions. The incident was primarily caused by a specific type of software bug leading to a crash [36307, 36305]. (f) other: The behavior of the software failure incident can be described as a specific type of value failure known as an integer overflow. This type of failure occurs when the system is unable to handle numbers that exceed its storage capacity, leading to incorrect calculations and system malfunctions [36307, 36305].

IoT System Layer

Layer Option Rationale
Perception sensor, processing_unit, embedded_software (a) sensor: Failure due to contributing factors introduced by sensor error - The incident with the Ariane 5 rocket failure was caused by a software bug that made incorrect calculations when overloaded with numbers, specifically due to an unexpected measure of velocity captured by a process from the previous software generation (Article 36307). (b) actuator: Failure due to contributing factors introduced by actuator error - The articles do not mention any specific failure related to an actuator error. (c) processing_unit: Failure due to contributing factors introduced by processing error - The failure of the Ariane 5 rocket was directly attributed to a software bug that caused incorrect calculations due to an overflow of integers, leading to a sequence of self-destruction and the tragic incident (Article 36307). (d) network_communication: Failure due to contributing factors introduced by network communication error - The articles do not mention any specific failure related to a network communication error. (e) embedded_software: Failure due to contributing factors introduced by embedded software error - The failure of the Ariane 5 rocket was caused by a software bug related to the embedded software that could not handle the large numbers involved, leading to the catastrophic outcome (Article 36307).
Communication unknown The software failure incident related to the communication layer of the cyber physical system that failed is not explicitly mentioned in the provided articles. Therefore, the information to determine whether the failure was at the link_level or connectivity_level is unknown.
Application TRUE [36307, 36305] The software failure incident related to the Ariane 5 rocket launch failure and the potential issue with the Boeing 787 are both examples of failures related to the application layer of the cyber physical system. In the case of the Ariane 5 incident, the failure was caused by a simple bug in the software that led to incorrect calculations due to an overflow of integers, which falls under the category of failures introduced by bugs and incorrect usage in the application layer. Similarly, the potential issue with the Boeing 787, where the control unit managing engine power distribution could enter a fail-safe mode if left on for more than 284 days, is also related to a software bug that could lead to engines shutting down unexpectedly during flight, indicating a failure due to bugs and incorrect usage in the application layer of the cyber physical system.

Other Details

Category Option Rationale
Consequence death, harm, property, non-human, theoretical_consequence (a) death: People lost their lives due to the software failure - The incident involving the Patriot missile defense system during the Gulf War resulted in 28 soldiers dead and 98 people injured due to the software failure [36305]. (b) harm: People were physically harmed due to the software failure - The incident with the Patriot missile defense system during the Gulf War caused physical harm as the missile failed to intercept the Scud missile, leading to casualties [36305]. (d) property: People's material goods, money, or data was impacted due to the software failure - The Ariane 5 rocket explosion caused a loss of $370 million due to the software bug [36307]. - The potential issue with the Boeing 787 software could lead to engines shutting down mid-flight, impacting the safety of passengers and potentially causing financial losses [36307]. (f) non-human: Non-human entities were impacted due to the software failure - The software failure incidents mentioned in the articles impacted rockets, satellites, and missile defense systems, which are non-human entities [36305, 36307].
Domain information, knowledge, other The software failure incident discussed in the articles is related to the following industries: (a) information: The incident involved the failure of the software used in the space industry, specifically in the European Space Agency's Ariane 5 rocket launch, which carried expensive scientific satellites [Article 36307, Article 36305]. (i) knowledge: The incident also pertains to the knowledge industry as it involves space exploration and the use of software in managing and controlling space missions [Article 36307, Article 36305]. (m) other: The incident is related to the aerospace industry, which is not explicitly mentioned in the provided industry options [Article 36307, Article 36305].

Sources

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