PET chart

The project evaluation tree is an analytical tree to be used primarily as a graphic check in basically the same manner as the management oversight and risk tree (see Chapter 18). The PET chart, however, contains fewer than 200 event symbols and no transfers the MORT chart contains approximately 1,500 events symbols, multiple transfers, transfers within transfers, and drafting breaks. The PET chart is divided into three branches procedures, personnel, and plant and hardware. 

It is self-tailoring in that for a simple inspection, mishap, or analysis involving only a few procedures, personnel, and/or facilities or items of hardware, the PET chart can be applied to the relevant items relatively quickly. For a complex situation involving many procedures, personnel, and/or facilities and items of hardware, many iterations of the PET chart are required, thus producing an in-depth analysis. 

Basically, the PET chart is just a graphic checklist. The general procedure is to identify each procedure, individual and/or organization, facility, and piece of equipment or hardware to be analyzed and then systematically use the appropriate branch of the PET tree, in conjunction with the PET user s guide, to evaluate each part of the system or project (Fig. 16-1). 

Color coding of the PET chart is recommended, using red for evaluation criteria determined to be less than adequate (LTA), green for items that are adequate, black for criteria or branches of the PET chart than do not apply to the particular project or item being evaluated, and blue to indicate areas with insufficient input data to make a decision. (This color-coding system is the same that is used for the MORT chart and the mini-MORT chart (see Chapter 18). 

The PET chart is used primarily as a working tool to guide the analyst through the analysis. Information, especially items identified as less than adequate (red) is transferred to a PET analysis worksheet (see Fig. 16-6). These worksheets are then used like other hazard analysis worksheets for hazard tracking and preparing a narrative summary of the analysis. 

First, as with other analyses, define the scope of the analysis and the ground rules. Then collect the appropriate input data organize the data into procedures, personnel, and facilities/hardware and systematically evaluate the system or project using the PET user s guide and the PET chart. Note that multiple copies of the PET chart may be required. 

For accident analyses and other efforts for which input information may be provided piecemeal, start the PET analysis as early as practical and update it as new information is available. Use the PET chart as a guide for organizing the accident investigation and collecting evidence (Figs. 16-2 through 16-5). 

Figure 16-3 Personnel branch of PET chart (except human factors).

Figure 18-4 Color coding. These colors are generally used on the MORT or Mini-MORT chart when performing MORT Analysis. They are also used for the PET chart.

Whether using the MORT chart or the mini-MORT chart to perform MORT analysis (or using the PET chart for PET analysis), the general approach is to use the chart as a working paper, begin as early as possible, add information as it is obtained until the chart is complete, and then use the com-... 

For information about courses and materials prepared by the author, including mini-MORT and PET charts, contact Joe Stephenson, S429 Honeywood Circle, Las Vegas, NV 89128. 

Figure 16-4 Human factors portion of personnel branch of PET chart.

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