ISO 26262:2018 - Road Vehicles Functional Safety Professional Free Practice Test — 30 Questions

Question 1

A vehicle manufacturer is developing a highly automated driving system where the primary safety goal, designated SG-ACCEL-D, aims to prevent unintended acceleration and has been assigned an ASIL D. The system architecture includes a primary electronic control unit (ECU-P) and a secondary ECU (ECU-S) for redundancy. However, analysis has revealed a potential common cause failure mode that could affect both ECUs. To address this, a novel, independent sensor monitoring unit (SMU) is introduced. The SMU is designed to detect the same hazardous event (unintended acceleration) and can independently initiate a safe braking maneuver. Assuming the SMU\'s design, development, and manufacturing processes are sufficiently independent from ECU-P and ECU-S to satisfy the criteria for ASIL decomposition, what is the highest ASIL that can be assigned to the safety goal for the SMU, SG-SMU-DECOMP, which is intended to mitigate the same hazard as SG-ACCEL-D?

Accepted Answer

ASIL B

Question 2

Consider a complex automotive electronic control unit (ECU) responsible for managing the braking system. The system\'s primary safety goal, to prevent unintended acceleration, has been assigned an ASIL D. During the safety analysis, it is determined that certain software modules within the ECU, due to their independent development and verification processes, can be considered sufficiently independent to warrant ASIL decomposition. If the ASIL decomposition process is successfully executed according to ISO 26262-9:2018, what would be the ASIL of the primary safety goal itself?

Accepted Answer

ASIL D

Question 3

Consider a complex automotive system designed to prevent unintended acceleration, with an initial safety goal of ASIL D. The system architecture involves a primary control unit and a redundant monitoring unit. During the safety analysis, it is determined that a specific failure mode in the primary unit could lead to unintended acceleration. To mitigate this, the safety goal is decomposed into two sub-goals: one for the primary unit ensuring its safe operation, and another for the monitoring unit verifying the primary unit\'s output. What is the fundamental prerequisite for successfully reducing the ASIL of these decomposed safety goals below ASIL D, according to ISO 26262:2018 principles?

Accepted Answer

Demonstrating sufficient independence between the primary control unit and the redundant monitoring unit to prevent common cause failures.

Question 4

Considering the overarching framework of ISO 26262:2018, what is the fundamental objective that drives the entire functional safety lifecycle for automotive E/E systems, from initial concept to end-of-life?

Accepted Answer

The prevention of unreasonable risk through systematic safety management across the product lifecycle.

Question 5

Consider a complex automotive system designed to prevent unintended acceleration, with an initial safety goal classified as ASIL D. Through a rigorous ASIL decomposition process, the system\'s electronic control unit (ECU) responsible for throttle actuation is assigned a decomposed ASIL of B, based on the implementation of robust safety mechanisms and sufficient independence from other potential failure sources. However, the overarching safety objective for the system remains to eliminate the risk of unintended acceleration. What is the correct ASIL classification for the fundamental safety goal of \"Prevent unintended acceleration\" after the ASIL decomposition of the ECU?

Accepted Answer

ASIL D

Question 6

Consider a complex braking system designed to prevent unintended acceleration, which has been assigned an ASIL D safety goal. During the system\'s architectural design phase, the development team proposes decomposing this safety goal into two independent functional elements, each intended to achieve an ASIL B integrity level. What is the correct interpretation of the ASIL integrity level for the original safety goal following this decomposition strategy?

Accepted Answer

The safety goal's ASIL remains ASIL D, and the decomposed elements must collectively achieve this ASIL D safety goal.

Question 7

Consider a vehicle manufacturer developing a new advanced driver-assistance system (ADAS) with a target ASIL D. During the initial phases of development, the project team identifies a critical need to establish a systematic approach for managing all safety-related activities and ensuring clear accountability. What foundational element, as prescribed by ISO 26262:2018, is essential for effectively orchestrating these efforts and demonstrating compliance throughout the product lifecycle?

Accepted Answer

The establishment of a comprehensive Safety Management Plan and a clearly defined organizational structure with assigned safety responsibilities.

Question 8

Consider a novel autonomous driving system feature that, if it fails, could lead to a situation where the vehicle deviates from its lane and potentially collides with oncoming traffic. The potential for serious injury or fatality to multiple occupants and external road users is high. This failure mode is estimated to occur under specific, but not rare, driving conditions that are difficult for the driver to anticipate and react to effectively. Based on the principles of ISO 26262, what is the most appropriate ASIL determination for the safety goal associated with preventing this specific failure mode?

Accepted Answer

ASIL D

Question 9

Consider a complex braking system where the primary safety goal, \"Prevent unintended acceleration,\" has been assigned an ASIL D. The system architecture allows for the decomposition of this safety goal into two independent safety elements, each contributing to the overall prevention of unintended acceleration. If the independence criteria between these two safety elements are rigorously met according to ISO 26262:2018 guidelines, what is the maximum ASIL that can be assigned to the safety requirements allocated to each of these decomposed elements?

Accepted Answer

ASIL B

Question 10

Consider a vehicle\'s electronic stability control (ESC) system, which has been assigned an ASIL C safety goal to prevent unintended vehicle yaw. To achieve this, the system architecture is designed with two independent processing units, each responsible for a portion of the ESC logic. The safety analysis has determined that if the ASIL C safety goal is decomposed into two independent ASIL B safety goals, one for each processing unit, the overall safety integrity can be maintained. What is the fundamental safety objective for each of these decomposed ASIL B safety goals in relation to the original ASIL C safety goal?

Accepted Answer

To achieve the target probability of failure of the ASIL C safety goal through independent means.

Question 11

Consider an advanced driver-assistance system (ADAS) designed to provide adaptive cruise control and lane-keeping assistance. During the preliminary hazard analysis and risk assessment (HARA) phase, a hazardous event is identified where the system, due to a latent fault in its sensor fusion module, incorrectly perceives a stationary object as clear, leading to a potential collision. The severity of this potential harm is assessed as high, the exposure to this situation is considered frequent, and the controllability by the driver is deemed difficult under certain operating conditions. Based on these inputs, what is the primary purpose of defining a safety goal in the subsequent conceptualization phase of the ISO 26262 V-model for this specific hazardous event?

Accepted Answer

To establish a top-level safety requirement that specifies the necessary risk reduction for the identified hazardous event, thereby guiding the development of functional safety requirements and ensuring the system's integrity against potential failures.

Question 12

Consider a scenario where a novel electronic control unit (ECU) is being developed for an advanced driver-assistance system (ADAS) that manages emergency braking. During the hazard analysis and risk assessment (HARA) for a specific failure mode of this ECU, a hazard is identified: \"Unintended full deceleration of the vehicle without driver intervention.\" The assessed severity of this hazard is classified as S3 (severe or life-threatening injuries, fatal accidents), the controllability is assessed as C2 (normally controllable), and the exposure is assessed as E3 (high probability of occurrence). Based on these assessments, what is the fundamental characteristic of the safety goal that must be established for this hazard?

Accepted Answer

It must define a top-level safety requirement aimed at preventing or mitigating severe injuries or fatalities, commensurate with the determined ASIL.

Question 13

Consider a complex automotive system where a critical safety function, initially assigned an ASIL D, undergoes ASIL decomposition. This decomposition results in several lower-level components being assigned ASIL B. During the safety validation phase, what is the primary consideration for demonstrating the effectiveness of the safety measures that were subject to this decomposition, in relation to the original ASIL D safety goal?

Accepted Answer

The safety validation must confirm that the combined effect of the ASIL B components, when integrated into the system, adequately fulfills the original ASIL D safety goal, potentially requiring system-level validation activities that provide evidence commensurate with ASIL D.

Question 14

Consider a complex automotive system where a safety-critical braking control function, designated ASIL D, and a non-safety-related infotainment feature, designated QM, are both executed on the same microcontroller. The ASIL D braking function requires specific, non-critical sensor data that is pre-processed by the QM infotainment feature before being passed to the braking algorithm. What is the most critical consideration for ensuring freedom from interference between these two software components, as per ISO 26262:2018 principles?

Accepted Answer

Implementing robust mechanisms to ensure the ASIL D component's integrity is not compromised by the QM component's execution or data handling.

Question 15

Consider a complex automotive system designed for autonomous driving, assigned an ASIL D rating. The development team has meticulously crafted the safety plan, outlining all necessary safety activities, verification methods, and validation strategies. According to ISO 26262:2018, what is the most appropriate confirmation measure for this safety plan to ensure its adequacy and the effective implementation of functional safety throughout the lifecycle?

Accepted Answer

A confirmation review of the safety plan conducted by an independent functional safety assessor.

Question 16

Consider a complex braking system where a critical safety goal, aiming to prevent unintended acceleration, has been assigned an ASIL D. The system\'s safety concept proposes decomposing this safety goal into two independent safety requirements, each assigned ASIL B, to be implemented by separate hardware and software modules. Assuming all criteria for independence as per ISO 26262:2018 are rigorously met and verified, what is the ASIL of the original safety goal that necessitates this decomposition?

Accepted Answer

ASIL D

Question 17

Consider a scenario where a complex automotive braking system has undergone system-level safety validation, and specific safety requirements have been allocated to the electronic control unit (ECU) hardware. To ensure the integrity of the braking function, what is the most appropriate method for validating that the allocated hardware safety requirements are met by the ECU\'s design and implementation?

Accepted Answer

Conducting a comprehensive hardware safety analysis, including failure mode and effects analysis (FMEA) and fault tree analysis (FTA), to assess the hardware's ability to achieve its safety goals and verify the effectiveness of implemented safety mechanisms.

Question 18

Consider a complex braking system function designed to prevent unintended acceleration, which has been assigned an ASIL D safety goal. Through a rigorous ASIL decomposition analysis, this safety goal is broken down into two independent safety requirements, each allocated to a separate hardware element. The decomposition process results in each of these elements being assigned an ASIL B. What is the correct interpretation of the safety integrity level required for the original safety goal in this scenario?

Accepted Answer

The original safety goal retains its ASIL D integrity requirement, necessitating safety mechanisms that collectively achieve this level.

Question 19

Consider a complex automotive braking system where the primary safety goal, identified as $SG_{BrakeControl}$, has been assigned an ASIL $D$. Due to architectural considerations and the need for efficient development, the system is decomposed into two functionally distinct and independent electronic control units (ECUs), ECU\_Alpha and ECU\_Beta. ECU\_Alpha is responsible for hydraulic pressure modulation, while ECU\_Beta manages sensor data fusion and actuator commands. Through rigorous analysis, including fault tree analysis and dependency assessments, it has been determined that the probability of a common cause failure affecting both ECU\_Alpha and ECU\_Beta simultaneously is negligible, and the independence criteria for ASIL decomposition are met. Consequently, the safety requirements allocated to ECU\_Alpha are assigned an ASIL $B$, and similarly, the safety requirements allocated to ECU\_Beta are also assigned an ASIL $B$. What is the ASIL of the safety goals associated with ECU\_Alpha and ECU\_Beta, respectively, following this decomposition?

Accepted Answer

ASIL B for ECU_Alpha and ASIL B for ECU_Beta

Question 20

Consider a complex automotive system where a hazard analysis and risk assessment (HARA) identified a critical safety goal with an ASIL D rating. Through a rigorous ASIL decomposition process, the system was redesigned into multiple independent elements, each assigned a lower ASIL. What is the fundamental implication for the original safety goal following a successful ASIL decomposition?

Accepted Answer

The original safety goal must still be achieved, but potentially through the combined efforts of the decomposed elements with their respective lower ASILs.

Question 21

Consider a complex automotive system where the Hazard Analysis and Risk Assessment (HARA) identifies a critical hazardous event leading to a safety goal with an ASIL D rating. During the system design phase, a specific function crucial for achieving this safety goal is identified. To manage the complexity and potential for common cause failures, the system architect proposes to decompose this function into two independent sub-functions, each implemented on separate hardware and software elements. Through rigorous analysis of independence criteria as per ISO 26262, it is determined that each sub-function can be assigned an ASIL B rating. What is the ASIL of the original safety goal after this ASIL decomposition has been applied to the sub-functions?

Accepted Answer

ASIL D

Question 22

Consider a complex automotive system where an initial hazard analysis and risk assessment (HARA) identifies a critical failure mode leading to a safety goal with ASIL D. The system architect proposes an ASIL decomposition strategy to manage the development effort and complexity. Following a successful decomposition, the system is re-architected into several interconnected elements, each assigned a lower ASIL (e.g., ASIL B and ASIL C). What is the fundamental implication of this ASIL decomposition on the system\'s overall safety objectives and the requirements that must be met?

Accepted Answer

The safety goals established prior to decomposition remain the ultimate objectives, and requirements are derived to ensure these goals are met by the decomposed elements.

Question 23

Consider a novel automotive system designed to assist drivers in maintaining lane discipline. During the hazard analysis and risk assessment (HARA) phase, a specific malfunction scenario is identified where the system might inadvertently steer the vehicle towards oncoming traffic. Analysis of this scenario reveals the following: the potential for fatalities or severe injuries is high, the operational situation where this malfunction could occur is frequent during normal driving, and the driver\'s ability to react and correct the vehicle\'s path in such an event is limited. Based on the principles of ISO 26262, which combination of the three core risk assessment parameters most accurately reflects this scenario and dictates the most stringent safety development requirements?

Accepted Answer

High Severity, High Exposure, Low Controllability

Question 24

Consider a novel braking system designed for autonomous vehicles that, in the event of a critical failure, could lead to a significant deceleration without driver intervention. During the Hazard Analysis and Risk Assessment (HARA) phase, a specific hazardous event is identified where the system unexpectedly applies full braking force while the vehicle is traveling at highway speeds. The assessment of this event indicates a high potential for severe injuries to occupants and other road users due to the abrupt and uncontrolled deceleration. Furthermore, the operational scenario analysis suggests that such a situation, while infrequent, is plausible during normal highway driving conditions. The controllability assessment concludes that a driver would have very limited ability to mitigate the consequences of this sudden, extreme braking. Based on these inputs, what is the fundamental determinant for the stringency of the safety measures required for this hazardous event?

Accepted Answer

The Automotive Safety Integrity Level (ASIL) assigned to the safety goal derived from this hazardous event.

Question 25

Consider a vehicle\'s electronic stability control (ESC) system, which has a safety goal to prevent unintended yawing moments that could lead to loss of vehicle control. This safety goal is initially assigned an ASIL D. Through a rigorous ASIL decomposition process, the system is partitioned into a sensor processing unit (SPU) and a braking actuation unit (BAU). The SPU is designed with sufficient independence and diagnostic coverage to achieve ASIL B, and the BAU is designed to achieve ASIL C. What is the correct interpretation of the safety goal\'s ASIL in the context of this decomposition?

Accepted Answer

The safety goal's ASIL remains ASIL D, as decomposition addresses the ASIL of elements, not the safety goal itself.

Question 26

Consider a complex automotive system designed to manage vehicle dynamics, which has been assigned an ASIL D for its primary safety goal of preventing unintended acceleration. Due to architectural considerations, the development team decides to decompose this function into two independent hardware modules, each responsible for a distinct aspect of the control logic. If the decomposition is deemed valid according to ISO 26262:2018, what is the most accurate implication for the ASIL of the individual hardware modules and the overall safety requirements?

Accepted Answer

The individual hardware modules can be developed to ASIL B, provided their safety requirements, when integrated, collectively satisfy the original ASIL D safety goal.

Question 27

Consider a scenario where an automotive supplier develops a braking control module as a Safety Element out of Context (SEooC) with an ASIL C rating. This SEooC is intended for use in various vehicle platforms. A vehicle manufacturer then decides to integrate this SEooC into a new electric vehicle model. What is the primary functional safety activity the vehicle manufacturer must undertake to ensure the safe integration of this SEooC, given that the SEooC was developed independently of any specific vehicle project?

Accepted Answer

Conduct confirmation measures to verify the SEooC's safety goals are met within the target vehicle's operational environment and system context.

Question 28

Consider a safety-critical braking system function with an assigned ASIL C. During the system design phase, this function is decomposed into two independent hardware elements. The first element, responsible for primary sensor data processing, is allocated ASIL B. The second element, handling actuator command generation, is allocated ASIL A. What is the ASIL assigned to the decomposed element that carries the most stringent safety integrity requirement resulting from this decomposition?

Accepted Answer

ASIL B

Question 29

Consider a safety-critical automotive system designed to meet ASIL D requirements. A particular hardware component within this system is protected by a safety mechanism that achieves 99% diagnostic coverage for single-point faults and 90% diagnostic coverage for latent faults. What is the primary implication of these diagnostic coverage figures in the context of achieving the stringent safety goals associated with ASIL D for this component?

Accepted Answer

The safety mechanism's diagnostic coverage is likely sufficient to meet the residual failure rate targets for ASIL D, assuming the underlying component failure rates are within expected bounds.

Question 30

Consider a complex electronic control unit responsible for managing a vehicle\'s adaptive cruise control system. A critical safety goal, identified as SG-ACC-001, has been assigned an ASIL C. During the safety analysis, it is determined that this safety goal can be decomposed into two independent functional elements, FE-ACC-001a and FE-ACC-001b. FE-ACC-001a, which handles sensor data filtering, is successfully implemented with an ASIL A rating. What ASIL must be assigned to FE-ACC-001b, responsible for actuator command generation, to ensure the overall safety integrity of SG-ACC-001 is maintained according to ISO 26262:2018 principles?

Accepted Answer

ASIL B

ISO 26262:2018 - Road Vehicles Functional Safety Professional Free Practice Test — 30 Questions

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