Checklist

Safety critical systems

Checklists are used to help avoid accidental omission of important preparation of equipment and systems. These may be routine operations like pre-flight checks on an airliner or relatively infrequent occasions like commissioning a nuclear power station or launching a spacecraft. The value of checklists is proportional to the complexity of the system and the consequences of a system failure. They may also aid in mitigating claims of negligence in public liability claims by providing evidence of a risk management system being in place. A signed off checklist with a document describing the listed checks may be accepted as evidence of due diligence. Conversely, the absence of a mandatory checklist may be considered evidence of negligence.^{[citation needed]}

Quality assurance applications

• Used in quality assurance of software engineering, to check process compliance, code standardization and error prevention, and others.^{[citation needed]}
• Often used in industry in operations procedures^{[clarification needed][citation needed]}
• In civil litigation to deal with the complexity of discovery and motions practice. An example is the open-source litigation checklist.^{[citation needed]}
• Used by some investors as a critical part of their investment process,^{[citation needed]}
• The creation of emergency survival kits, first aid kits and other collections of diverse apparatus, to ensure that the set is complete.^{[citation needed]}
• Janitorial checklists are used for quality control.^[17]

For information

• An ornithological checklist (Category:Ornithological checklists), a list of birds with standardized names that helps ornithologists communicate with the public without the use of Latinised scientific names.^{[citation needed]}
• A biodiversity checklist is a list of organisms recorded from a given geographical region or taxon. These include worldwide lists indicating the continued existence of species within specified taxa, and are also used to record the species found in countries, bioregions, or specific protected areas. They may be a form of database.^[18][19]
• A popular tool for tracking sports card collections. Randomly inserted in packs, checklist cards provide information on the contents of sports card set.^{[citation needed]}

Mode of use

A checklist may be used to identify the action, after which it is done, then checked off as complete and the next item identified, known as the read–do, do–list or call–do–response process, or the tasks may be done, and then the checklist consulted to ensure that nothing has been left out, the do–confirm procedure, in which the status of tasks must be remembered until checked off, which may result in more errors,^[16] or challenge, verification, and response process, in which the checklist is used after the tasks have been completed. Both methods have merit and suitable applications, and the most suitable type of checklist will depend on the type of operation.^[10]

In the call–do–response system, the checklist is used to lead the operators through a step-by-step procedure where one operator directs the others, following the list. Each item requiring configuration is listed on the checklist and all relevant operators must be present while the checks are done. This method tends to be more detailed and time-consuming. It may be more appropriate for systems which are less familiar to the operators.^[10]

In the challenge–verification–response, the operators prepare the system following a standard sequence of actions performed from memory, then use the checklist to verify that the critical items have been correctly configured. One operator reads the challenge part of the checklist, the designated parties verify the status, and one of them provides the appropriate response. This is done in sequence until the list is complete. It may be ticked or signed off as specified. This method is efficient, as each operator can get on with their checks and then when the checklist is run through, all the relevant crew are updated on the system status.^[10]

Physical characteristics

Physical characteristics are things such as the actual size of the document, contrast, colour, and typography. The main factors in typography are legibility of text and readability in the conditions in which the document is expected to be used.^[10]

Legibility of text involves the selection of characters to enable the reader to identify them quickly and positively discriminate them from other characters. Readability is the quality of the word or text which allows rapid recognition of single words, word groups, abbreviations, and symbols.^[10]

Thousands of fonts are available, in two major groups: Roman (with serifs) and sans-serif. Research has shown that sans-serif is more legible than Roman as the absence of serifs presents simple and clean typeface. Arial or Helvetica are preferred.^[10]

The consensus of researchers is that lowercase is more legible because the pattern of the whole word is more familiar, and the pattern of ascenders and descenders is helpful for recognition. The occasional use of uppercase words for emphasis or in acronyms is acceptable, particularly where this is the common usage.^[10]

Font size is important for readability, especially for older operators. A font size between 14 and 20 points is recommended for reasonably well illuminated situations. Font size less than 10 points is not recommended. Checklists for use in poorly illuminated conditions should use a larger font for improved readability. Black text on a white background is generally preferred for best contrast, though in some cases a yellow background is acceptable.^[10]

Other factors influencing readability and reducing error include both horizontal and vertical character spacing, stroke width and character height to width ratio, and line length. Italics reduce readability of large areas of text but are acceptable for emphasis of a few words. Bolding does not affect readability significantly, but is useful for emphasis, and is best used with discretion. The use of multiple type faces in body text can be confusing and significantly reduces readability, so should be avoided. Contrast is more useful than colour to provide visibility of characters. White on black can be useful if dark adaptation must be preserved, but is not optimum when illumination is good. If checklists are plastic laminated, an anti-glare finish should be used to prevent disruption by highlights. Opacity of the paper is important if printed on both sides or there is a possibility of backlighting.^[22]

Content and layout

The workload and time available should be considered.^[6] Each listed item should be necessary and together they should be sufficient. Only necessary instructions should be included.^[20] A checklist should be as brief as possible without compromising clarity.^[6] Items should not be over-detailed in description nor ambiguous. A checklist should not try to define or describe procedures which should be familiar to the checker, though critical steps may usefully be listed in order when order is important.^[20] Numbering the items usually helps with place-keeping.^[6] It may be useful to cross-reference the checklist to the standard procedure document, where the process is definitively described in detail, particularly for training and audit purposes. This makes it easy to check if there is any doubt, but does not distract the user. Version number and date may be required to ensure that the current authorised version is in use.^[20]

Ordering of the list should be logical. Where chronological order is important, it should be indicated by order on the list. The most convenient and reliable checklists are normally completed from top to bottom in a single session. It should be easy to recover from any interruption without risking missing an item or redoing a check unnecessarily. Grouping items which can be done at the same time or place, or by the same person, often improves efficiency. Where items to be checked are spatially distributed, an order minimising travel or search time is efficient.^[20]

Checkboxes at the beginning of each item are easier to find and follow to the next incomplete check. A keyword at the beginning of the text will help ensure that the correct box is ticked.^[20]

Format

Checklists are often presented as lists with small checkboxes down the left hand side of the page. A small tick or checkmark is drawn in the box after the item has been completed. If practicable a check should not be split over two pages.^{[citation needed]}

Other formats are also sometimes used. Aviation checklists generally consist of a system and an action divided by a dashed line, and lack a checkbox as they are often read aloud and are usually intended to be reused.^{[citation needed]}

Some checklists must be signed off and kept as evidence, others may be re-usable. This may affect the format and materials.^[20]

Errors

Long or confusing items, an inconvenient order, or any other characteristic that causes the users to perceive it as an obstacle will increase the chances that when constrained for time, the operators will revert to alternative methods, omit items or disregard the checklist entirely.^[6]

Error conditions that may occur include:

• Using the wrong checklist.^[6]
• Difficulty in finding the right checklist.^[6]
• Difficulty in confirming that the checklist is the right one for the situation.^[6]
• Losing track of where one is in the checklist.^[6]
• Missing a step or not completing a step after an interruption.^[6]
• Misunderstanding the action required by the checklist.^[6]
• Difficulty in confirming that an action required by the checklist was done correctly.^[6]
• Difficulty in finding the next step after a conditional statement.^[6]
• Difficulty in reading a checklist.^[6]
• Lack of clarity about who should carry out a checklist action.^[6]
• Failing to complete the checklist.^[6]

History

During the National Transportation Safety Board (NTSB) hearings into the crash of Northwest Airlines Flight 255, human factors specialist Earl Weiner testified that he "did not know of any human factors research on how a checklist should be designed". NASA research into the matter concluded that as of 1989, there was basically no human factors research available anywhere specific to aircraft checklists.^[10]

The NTSB recommended that the FAA investigate ways of presenting checklists that produce better performance. The Safety Board also recommended that the FAA should specify typography criteria for checklists for commercial operators. Researchers found problems with both the physical design and social issues associated with the use of checklists which degrades effective use. Two documents were produced by NASA, Degani, Asaf; Wiener, Earl L. (May 1990). Human Factors of Flight-Deck Checklists: The Normal Checklist. NASA Contractor Report 177549 (Report). NASA. and Degani, Asaf (December 1992). On the Typography of Flight-deck Documentation. NASA Contractor report # 177605 (Report). NASA.. This was followed by a document from the UK CAA: "CAP 676: Guidance on the Design, Presentation, and Use of Emergency and Abnormal Checklist".^[10]