Sample Worksheet - Safety Critical Systems

[Worksheet 1, Safety-Critical Software]

Read the articles, "Real-Time Operating Systems: The Patriot-Missile System Failure", "Patriot Missile Failure", and "Fatal Error: How Patriot Overlooked a Scud."

To understand the mechanics involved in the patriot computer system failure, complete the description of the software-driven weapons:

QUESTION:		RESPONSE:
1. Real-Time means …		1.
2. The patriot’s brain was designed to …		2.
3.The error in the computer generated data was caused by …		3.
	a. In decimal value, the error was about …		a.
	b. Eight hours of use produce a timing error of _____, creating a range error of _____ meters.		b.
	c. 100 hours magnifies this error to …		c.
	d. During this 100 hour time interval, the scud was able to travel _____, which is out of the "range gate"		d.
4. The immediate fix applied by the soldiers was … (though it was not apparent why)		4.
5. Specs called for _____ hours of continuouse operation.		5.
6. The tacit assumption was …		6.

Read the report, "Activities of the House Committee on Government Operations". Respond to the questions below.

Give some reasons why the initial reports of the Scud destruction were so inaccurate. Some factors that contributed to the high failure rate of the Patriot missiles included:
The army evaluation of the Patriot’s performance was performed by the following group(s):
Summarize the conclusions/problems/inadequacies found relative to each of the following:

CONDITION/OBSERVATION/

QUOTE (from House Activities Report):
PROBLEM/CONFLICTING EVIDENCE/CIRCUMSTANCE/

ETHICAL IMPLICATIONS

"Army’s assessment of Patriot effectiveness could not be supported by the data."

The spreadsheet was actually an inaccurate summary of information.

Gaps and inconsistencies existed between the data presented on the spreadsheet and the supporting records.

The report included information on only about one-third of the Saudi engagements, although the Project Managers’ assessment cited it as a source for all engagements.

Describe some ethical implications based on the following information from the report.

CONDITION/OBSERVATION/QUOTE	ETHICAL IMPLICATION
Spreadsheet was not intended to be used as an analysis of the Patriot’s performance
"… therefore, he made no attempt to analyze and refine the data."
"… there were no records supporting the spreadsheet entries."

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CONDITION/OBSERVATION/ QUOTE (from House Activities Report):	PROBLEM/CONFLICTING EVIDENCE/CIRCUMSTANCE/ ETHICAL IMPLICATIONS
"Army’s assessment of Patriot effectiveness could not be supported by the data."
The spreadsheet was actually an inaccurate summary of information.
Gaps and inconsistencies existed between the data presented on the spreadsheet and the supporting records.
The report included information on only about one-third of the Saudi engagements, although the Project Managers’ assessment cited it as a source for all engagements.