TBM Checklist Design Principles

A recent discussion about radio communications taught me something about checklist design.

Many aircraft in our TBM fleet have a registration number that corresponds to the model number with the first owner’s initials at the end.  For example, a friend of mine, Dean Johnson, just purchased N700WE.   On paper, it is a great registration number.  On the radio, however, that registration number is a mouthful -- adding 13 syllables to every transmission.  Even when the controller shortens it to the last three symbols, it is six syllables appended to every radio call. 

Dean is also a recent CFII, and always seeks to use (and model for his students) standard, FAA-approved radio phraseology.  He discovered Jeff Kanarish’s podcast (IFR Flight Radio Show – IFR Flight Radio) and his IFR-related radio book (Radio Mastery for IFR Pilots).  At the end of each podcast, Jeff invites questions regarding radio procedures.   Dean wrote Jeff and asked what a well-known radio procedures expert thought about shortening the registration number by two syllables to “seven hundred whiskey echo.”   

Jeff replied that there is  

“a precedent for pronouncing double-zero as ‘hundred’ in ICAO radio procedures. For example, when ATC clears an aircraft to Flight Level 200, they refer to it as Flight Level Two Hundred.

That said, give it a try your way and see how ATC responds. If controllers consistently reply ‘November Seven Hundred Whiskey Echo’, you are okay to continue with that. If they come back with ‘November Seven Zero Zero Whiskey Echo’, I'd follow the controller's lead.

The most important point of a call sign is that it distinguishes your flight from all other flights in ATC's system. The second most important point is that a call sign should never trip a controller up and cause him to doubt who he is talking to. As long as you and the controller are in sync, you are doing it right.”

It was the last line that really stuck with me.  Synchronization between the controller and the pilot is really the crux of effective communication.   

That synchronization also plays a critical role in checklist design.  If the author of the checklist and the user of the checklist are in sync with what needs to be done, when it needs to be done, in what order, and to what degree, then the checklist is serving its purpose. 

An “abbreviated normal procedures checklist” sets forth a set of tasks the pilot must perform or verify to configure the aircraft for a particular phase of flight.  This is the type of checklist most of us are familiar with.  Many researchers have worked on creating the most effective (i.e., useful for the safe conduct of flight) abbreviated normal procedures checklist.  Some of the many required elements are effective typography, accurate content, and good ergonomics.  (Abnormal and emergency procedures checklist are a different animal, and I may discuss those in a future article.)

After refamiliarizing myself with much of the available research, I have designed a sample normal procedures checklist, and have made it available on my website – www.GoldbergAviation.com – in .docx format.  That sample incorporates some best practices that I will discuss below.  I hope that it can serve as a template for developing an abbreviated normal procedures checklist that is appropriate for your aircraft, its POH, its equipment, and your missions.

 

Typography

It turns out that typography is important.  Although newspapers, magazines, and other publications typically use “serif” fonts (fonts with small lines at the ends of the characters), research has shown that “sans serif” fonts – fonts without those small lines – actually have better word-shape recognition, and are easier to interpret because the characters are more dissimilar.  Thus, Edward Tufte, author of the seminal work The Visual Display of Quantitative Information, strongly favors Gill Sans in his publications.  The standard version of Microsoft Word offers Gill Sans MT as a standard font, and I have used it on my sample checklist.  I have used no italics, and have only sparingly used reverse fonts (white letters on a black background) to minimize letter shapes that require unnecessary interpretation effort.

There is a preponderance of upper-case letter usage throughout example checklists from military and Part 121 operators.  Interestingly, the research that I reviewed on effective checklists did not uniformly endorse all-upper-case usage and, in fact, included some checklists that were all lower-case examples.  The problem with using all upper-case letters is an illusion called “striping” where the checklist appears to be nothing but horizontal stripes on a page.   

There is some research on word recognition outside of aviation that favors a mix of upper and lower case – just like what you are reading now.  I have chosen to experiment with a mix – the item to be checked is in mixed upper and lower case, while the condition or challenge is upper case.  It is easy to switch back and forth in Microsoft Word should you wish to do so.  Without doubt, long chunks of text should be set in a mix of upper- and lower-case for maximum readability.

The age of the reader determines the size of the font.  Fitting everything onto one page may help the ergonomics of the checklist, but being able to clearly read every line, without skipping a line, is the far more important governing design criterion.  I have used a 12-point font and 0.2” row height.  I have also chosen to implement the more traditional string of periods (called a connector line) that visually connects the item to its desired condition, but I could not help but wonder about the efficacy of shading the table cell to accomplish the same goal.  Irrespective of the punctuation or shading, the wider the gap between the item and its desired status, the more likely the pilot is to misalign the two.

My sample checklist is printed black on white for maximum readability in low or colored light, and keeps the line lengths short so that the readers’ eyes do not slip a line between the item and its desired condition.  Research suggests that color print can introduce an unnecessary cognitive load, and that low-contrasting colors (such as blue on black or vice versa) are poor choices.  However, if you want to get fancy, black type on a bright lemon-yellow back ground has been shown to have the highest readability under normal cockpit lighting.

 

Content

The checklist is set up in a challenge-response format.  The item to be checked is on the left and its desired state is on the right.  This is thoroughly conventional and a well-established best practice.   

Precise wording of the desired state is key to an effective checklist challenge/response pairing.  Specifically, the response should be the desired status or value of the item (29.92 inches or 24.5 volts) and not simply “CHECKED,” “VERIFIED,” or “SET.”

Every checklist should use manufacturer-standard nomenclature and terminology.  If the manufacturer calls the “Bleed Air” switch the “Bleed Valve” switch, the checklist should as well.  Keep in mind that an abbreviated normal procedures checklist should agree with the POH and differ only in abbreviation (omitting the explanatory material in the parent manual). 

Dividing the checklist into phases of flight adheres to best practices for human factors engineering.  A pilot who reaches the end of a section and states “Taxi checklist is complete” has solidified his or her state of awareness, and is better able to move mentally to the next section with the assurance that the previous section has been completed.

There can be a conflict between (1) ordering the items according to a “flow” (a series of cockpit actions that move forward with visual cues, such as adjusting instruments from one side of the panel to the other), and (2) the importance of doing certain tasks in a certain order.  Absolute guidance on the better approach is impossible, although in all cases where the POH speaks, the POH obviously rules.  For example, some sections such as engine start may need to be in a specific order, while other sections such as the descent checklist could be conducted using a flow.  Another conflict that could arise is between putting the most critical items early in the checklist (Flaps …TAKEOFF), so that they are perhaps more likely to be performed, versus executing a flow, which is perhaps more likely to be completed in its entirety. 

Ergonomics

 The sample checklist available on my website is formatted for one 8.5” x 11” page and can be folded in half.  Had the example not fit on an 8.5” x 11” sheet due to type size, content, or other considerations, legal size paper of 8.5” x 14” was the next best option.  The goals of putting normal procedures from “Inside Inspection” to “Shutdown” on a single sheet of paper are simplicity and manageability.

 The industry has numerous examples of pilots not using checklists and making fatal errors.  The final authority and expert on the checklist for your airplane is your POH.  While I cannot stress enough that the manufacturer’s checklist is the final authority, we at Goldberg Aviation hope that you can use this nudge from us to develop a checklist that better suits your equipment and missions – and that you feel that it is “your” checklist, not the product of a manufacturer or training company who doesn’t fly your particular missions.  However, verify, verify, verify your work against the POH.

 If you have questions, comments or suggestions regarding the development of effective checklists, I’d love to hear them.  If you have an especially effective checklist, I’d like to see it and post it on my site.  I am going to work on improving mine and will keep an updated version on my site.  At the same time, leave your comment and let’s turn the comments of this article into long list of suggestions and best practices from the TBM world.  Or just email me from my website at www.goldbergaviation.com if you have questions or comments.

 Let’s all work to make sure that, just as our radio calls are synchronized with ATC, our checklists are synchronized with our equipment, POHs, human factors, and missions.