Safety-Critical Systems CTEL-TM-SM Practice Questions (Page 6)

Questions 26–30

1. 26expert · hard

   A test manager is reporting on the safety readiness of a SIL 2 system to a certification body. The test manager has collected data on requirements coverage, defect density, and test execution progress. The certification body asks for evidence that the system is safe to release. Which additional information would most strengthen the safety readiness argument?

   • AA summary of the test team's experience and qualifications.
   • BA traceability matrix showing that every safety requirement has at least one passing test case.
   • CA list of all test tools used and their versions.
   • DA chart showing the number of test cases executed per day.
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2. 27foundation · easy

   What is the primary purpose of maintaining traceability from safety requirements to test cases?

   • ATo provide a way to assign test cases to specific developers.
   • BTo demonstrate that every safety requirement has been tested and to support impact analysis when requirements change.
   • CTo allow testers to skip testing requirements that are considered low risk.
   • DTo reduce the number of test cases needed by grouping similar requirements.
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4. 28application · medium

   A team is testing a medical infusion pump that delivers medication to patients. The pump has a safety mechanism that must trigger an alarm and stop the motor if the pressure sensor detects an occlusion. The test environment uses a hardware-in-the-loop simulator that can emulate sensor readings. Which test approach best validates the robustness of the occlusion detection mechanism?

   • APerform boundary value analysis on the pressure threshold using only the software model, without the hardware simulator.
   • BInject simulated sensor faults at various pressure levels and verify the alarm and motor stop activate correctly within the required response time.
   • CRun only normal operation scenarios to confirm the pump delivers the correct medication dosage.
   • DReview the code for the alarm logic and rely on static analysis to prove correctness.
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5. 29application · medium

   A test manager is working on a SIL 2 system that must comply with IEC 61508. The team has developed test cases, but the test manager discovers that some test cases cannot be traced back to any specific safety requirement. What is the most appropriate action for the test manager to take?

   • AInvestigate the origin of the untraceable test cases and either link them to a requirement or document their purpose.
   • BMark the untraceable test cases as 'informational' and exclude them from the compliance evidence.
   • CRemove the untraceable test cases because they do not contribute to safety requirement coverage.
   • DKeep the untraceable test cases but do not document their origin since they are already written.
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6. 30foundation · easy

   Which of the following is a direct consequence of a system being assigned a higher Safety Integrity Level (SIL)?

   • AThe system can be tested using only manual testing techniques
   • BThe testing can be completed in a shorter time due to increased confidence
   • CThe test plan must include more extensive documentation and traceability
   • DThe number of test cases is reduced because the system is more reliable
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