Driving and flying have some similarities. In both cases, you are responsible for the operation of a heavy piece of machinery that has the potential to hurt you as the operator, as well as others that get in your way. In both cases, poor operating practices can lead to unnecessary outcomes that can create a combination of inconvenience and high out-of-pocket costs. A case in point: Running down a battery. It’s easy to do in a car (leave the door cracked open with the key in the ignition and the dome light on) and in an airplane (leave the master switch on).
When we learn to drive a car, though, we don’t learn to use checklists. We just…do stuff. But think about what you learn fairly early as a driver. You learn to work in a pattern to start up and to shut down the car. Some of us put the seatbelt on before closing the door, some after. Some of us set the parking brake before the car is shut down, some after, and some not at all.
The reality is that we learn to do things in a predictable pattern, or flow, when we drive. We don’t use checklists. Airplanes are different. The environment is three-dimensional versus two-dimensional. Cars do not have retractable landing gear or adjustable propellers. We don’t need to memorize speeds in our cars that affect the operation of certain items like the flaps or the aforementioned retractable gear. Plus, we don’t fly airplanes nearly as often as we drive our cars.
But the idea of a flow is transferable. If you watch pilots in more sophisticated airplanes—especially those with crews of two or more—you will see that they often follow a predictable pattern for each checklist. While companies and manufacturers differ in their philosophies, the flow is a commonly accepted practice.
At its simplest level, a flow is a series of visual and tactile checks that a pilot can use to verify proper switch/lever/button/dial/control position. For example, prior to applying electrical power to a airplane, a pilot might physically touch each switch in the cockpit, or only certain designated switches, to make sure that everything is set just so. This is done primarily to avoid a problem as a result of mechanics doing work on the aircraft and forgetting to return systems to their normal condition. Likewise, after electrical power has been applied to an airplane, the pilot will usually follow a pattern of testing the functionality or set-up of each system.
In each case, the flow is followed by the checklist. It can be done as either a Challenge-and-Response (C/R), in which one pilot reads the checklist line by line and the other responds accordingly, or it can be done as a Read-and-Response (R/R), in which case the pilot who performed the flow reads the checklist aloud and verbalizes that each item is complete. What is very rare is one pilot reading each item, and then doing it. This actually slows things down and increases the risk of an error because of a radio call or other distraction.
Flows transfer well to most general aviation aircraft. In fact, some never really had a checklist (Piper Cub), so a flow is the only option. Flows are not always appropriate, but they can expedite pre-departure checks (runups) and after-landing and shut-down duties.
Work with your CFI to set one up (assuming s/he is game), or carefully practice one yourself using a poster or photo of the cockpit. A flow is not a replacement for the checklist, but merely a tool to use the checklist more efficiently.—Chip Wright