Second of three Good Practice Notes on Human Factors in the design/writing of operating procedures.

1. Good Practice Note: Applying Human Factors to Procedure Writing: Part B,
Action Steps –Special Types
1. Non-Sequential steps.
The user will assume the steps must be performed in the order listed unless
the procedure states otherwise. Some times, the action steps are not orderdependent, i.e., the steps can be carried out in any order.
When that is the case try to save the user time and frustration and reduce
likelihood for error by putting the steps in a “natural” order. For example,
close multiple valves that are located close to each other instead of requiring
the operator to walk back and forth or climb up and down a ladder needlessly.
If a sequence can be done in any order, state that clearly in the procedure
step or in a note immediately preceding multiple steps.
2. Repeated steps.
Some tasks require the user to perform a step multiple times. For these
steps, state the following in specific terms:
•
When or how often the action is to be performed.
•
Conditions under which the action no longer needs to be carried out.
EXAMPLE:
MONITOR tank level every 30 min until level reaches “Max
Normal” (45 ft.)
If the recurrent step requires monitoring on a continuous basis and a data
sheet is required, include a data sheet with the procedure, either in the text or
in an appendix, as appropriate.
3. Concurrent steps.
a. When two or more steps must be performed at the same time, state
specifically which steps are simultaneous by using terms such as
“concurrently,” “simultaneously” or “at the same time”.
EXAMPLES:
INCREASE inlet flow
AND simultaneously MONITOR outlet flow to maintain level
at 60 cm.

2. ADJUST indicator brightness by rotating thumbwheel while
depressing “Indicator On” button.
b. If the concurrent action(s) require two persons, place a note preceding
the action step(s) that specifies:
•
Which steps are concurrent.
•
Personnel needed to perform each step.
•
Location where each person will perform their respective actions.
•
Means of communication between locations.
EXAMPLE
Steps 27 through 30 require an outside operator at the tank and a
controller in the control center working together. Maintain continuous
communication via area communication system or two-way radio.
4. Time-dependent steps.
Some steps must be performed within certain time constraints. Those time
constraints need to be specified precisely and, if possible, quantitatively.
When the time constraint applies to a single step, write it directly into that
step. When there are multiple actions to be performed within the same
constraint a note preceding the applicable steps is acceptable.
EXAMPLES:
VERIFY “Oil Pre-Lube Pump” stops after 3 minutes of
operation.
OR
Action steps 7 through 10 must be performed within 10 minutes
5. Conditional statements. (Action taken only if/when specified condition
exists).
a. Put the condition as the first word, bold and underline. “IF” is used for an
unexpected but possible condition. “WHEN” is used for an expected
condition.

3. EXAMPLE:
IF product temperature is above 90F,
NOTIFY Controller
EXAMPLE
WHEN controller output reaches 10%,
PLACE controller in AUTO.
b. The specified condition always comes before the action because the user
needs this information to decide whether to perform the action. The “IF” or
“WHEN” clause is followed by a comma. It is a good idea to place a
“THEN” after the comma and before the verb statement, especially when
there are multiple conditions or multiple steps to be performed depending
on the answer to a condition; but it’s not necessary to use it when it is
obviously implied.
EXAMPLE:
IF drain sump level is above the HIGH LEVEL limit,
THEN DRAIN sump using NOP 31.1.A.
AND NOTIFY control room operator
AND ALIGN sump flow to catch basin.
c. Use “AND” to link two or more conditions that must be met before an
action is performed.
Use “OR” to link two or more conditions when at least one of them must
be met before an action is performed.
EXAMPLES
IF <Condition A exists> AND <Condition B exists>,
THEN INITIATE controlled system shutdown (NOP-001).
IF <Condition B exists> OR <Condition D exists>,
THEN NOTIFY Supervisor and Control Center
AND INITIATE abnormal condition system shutdown
procedure (AOP-001)
d. Where three or more conditions must be determined, a vertical list is
preferred.
EXAMPLE

4. IF any of the following conditions exist:
<Condition A exists>,
OR <Condition B exists>,
OR <Condition B exists>,
THEN GO TO Step 30.
e. Be careful when using “AND” and “OR” together in a one step Avoid
using them together in the same phrase. The logic can be easily
misinterpreted.
Preferred:
SAMPLE
IF <Condition A exists> AND <Condition B exists>,
OR
IF <Condition A exists > AND <Condition B exists> ,
THEN GO TO Step 50.
Instead of:
IF <Condition A exists> AND <Condition B exists> OR
<Condition B exists exists>,
THEN GO TO Step 50.
f. In some cases it may be necessary to state exactly what to do if the
expected condition is NOT met.
EXAMPLE:
IF <Condition A exists>,
OPEN Drain.
OR,
IF <Condition A exists> does NOT exist,
NOTIFY Supervisor immediately.