Concept provides definition of relationship between safety and reliability, personnel safety measurement, and equipment safety evaluation. Safety systems cope with single or combined risks. Cost and effectiveness of alternate hypothetical safety systems are estimated and used as basis for final system design

Hano, G.

English

NASA Technical Reports Server

June 1971	 Brief 71-10183 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology. Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Generalized Safety Equation: A Concept 
A proposed concept, based on a simple and 
straightforward mathematical probability model, 
attempts to provide a means of defining the re-
lationship between safety and reliability, as well as 
measuring personnel safety and evaluating equipment 
safety. 
The probability function P(x) is defined as the total 
probability that a specific safety category, x, will not 
sustain injury or damage in excess of a defined degree. 
The confidence placed in P(x) is directly related to the
design. However, effectiveness equations should include 
all categories of interest. For example, if a product's 
safety system is effective for the public, it will in-
variably be beneficial to the safety of public property; 
conversely, a system which prevents equipment 
damage generally contributes to the safety of operat-
ing personnel. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Code A&TS-TU 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B71-10183 
Patent status: 
No patent action is contemplated by NASA. 
Source: George Hano of

IBM Corp.
under contract to

Marshall Space Flight Center

(MFS-20522) 
. thoroughness with which the hazards are identified 
and the effects on the safety category are analyzed. 
When the desired numerical value of P(x) cannot 
be achieved solely through reliability, a safety 
system must be incorporated. However, the safety 
system need not prevent injury or damage from 
all known hazards. It is sufficient that injury or 
damage be prevented only for enough hazards 
to achieve the desired P(x) value. 
Using this technique, safety systems can be hy-
pothesized to cope with any single risk or com-
bination of risks. The cost and effectiveness of 
alternate hypothetical safety systems can be es-
timated and used as a basis for the final system
Category 06 
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Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	
will be free from privately owned.rights.
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Generalized safety equation - A concept

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