The Therac-25 and Its Accident Investigation - Case Study Example

When u fix an old bug, it is highly likely that anew bug will develop. After fixing a bug, there is only a fifty per cent chance that the particular program will function over a similar length of time before failing, the same way it did before the bug was rectified. This means that the manufacturer’s claims that the machine’s safety was improved after it was fixed were totally unfounded. The manufacturer’s claim that the machine could never break down, even after getting and rectifying numerous problems was groundless.

So long as the manufacturer had the conviction that the machine could never cause an overdose of radiation, they would not notice any deficiencies in their machine. As much as many people would love to point fingers at the manufacturer as the cause of the Therac-25 accidents, the technicians and operators who operated the machine also made some mistakes which caused the accident. For instance, it was somehow strange that the operators of the machine got comfortable running the machine despite the regular error notices it issued.

The machine normally issued forty error notices in a single day. This was bad since the cost of the Therac-25’s failure may possibly be death and it was the operator’s responsibility to insist for a properly functioning machine without faults. They could also have demanded a clear documentation that showed the machine’s errors and their possible causes. They also over relied on the safety statistics of the machine which were inflated as stated by the manufacturer. This made them not to investigate any overdoses possible hence putting the lives of the patients in danger.

The federal government had a fair share of blame in the accidents because they knew that the manufacturer’s engineering practices were poor but still allowed the use of Therac-25. They seemingly had too much faith in the safety statistics that were posted by the manufacturer and therefore never took a keen interest in the safety precautions. The accidents were caused by institutional and engineering mistakes which could have led to even bigger disasters had the machine’s operation not been suspended.

The manufacturer never had an independent review on the software code and therefore had not followed the right procedure. They never considered the software’s design when assessing the machine’s ability to produce the expected results and if there were any failure modes in its operation. The machine never explained any error codes so the operators just overrode the warning signs since they could not tell if there was an error or just a false alarm. The manufacturer never believed any complaints since there were overconfident that the machine would never fail, to make it worse, the hardware and software combination was never tested until after its assembly at the hospital.

On the engineering side, the machine failed only when a non standard keystroke was entered on terminal VT-100. This machine never had hardware interlocks which could prevent the beam from running in high energy mode when the target was not in position. The programming engineer used software from an old model. The old models used hardware to cover their faults but could not report the faults hence leaving the machine to operate with the