Tuesday, June 05, 2007

Flows & Checklists

There are many things about airline flying that are very different from GA flying. You often cannot apply techniques from one to the other. I'm reminded of a Piper Aztec crash about 50 years ago. It was being flown by a TWA Constellation pilot and two other TWA pilots were riding along when they lost an engine shortly after takeoff. The airplane wasn't climbing well - the first Aztecs had only 150 hp per side - so the pilots applied the engine-out technique used in the Constellation: deploying the flaps. The results were predictable and an aviation truism was born: "The only thing more dangerous than an airline pilot in a light plane is two airline pilots in a light plane." That said, there is one area of airline operations that GA pilots would do well to mimic: our usage of flow patterns and checklists.

Most GA instructors do teach their students to use checklists, but they are most often taught as "do-lists." In other words, as you read each item, you flip the switch, adjust the knob, or read the gauge that it directs you to. This can be cumbersome, as your attention is continually flitting between the checklist and the instrument panel, and longer checklists can take a long time to work through. Many pilots stop using checklists as soon as they have the procedures memorized and they're out of their instructor's watchful gaze. When I was an active CFI, I found that advanced students who'd been flying on their own for long had to be cajoled and threatened into consistent checklist usage.

At the airlines, the desire to keep one's job provides ample motivation to use checklists and comply with the other dictates of standardization. Fortunately, we have a pretty good system of checklist usage. They tend to be fairly short given the level of complexity in our cockpits. If it's not important, it's left off the checklist, and if a number of switches can be grouped into one item, they are (de-ice boots, prop anti-ice, pitot-static heat, and windshield heat are all grouped under "Ice Protection," for example). Furthermore, checklists are actually used as checklists, not do-lists. You first configure the airplane appropriately for the stage of flight and then read the checklist to verify that the listed items have been accomplished.

"But wait!" you protest. "My instructor told me not to memorize the checklist!" Well, your instructor told you that so you wouldn't ditch the checklist the moment he was out of the plane! If you're using the checklist to verify everything, it's perfectly acceptable to accomplish the procedures by memory. At the airlines, we memorize every procedure for each normal stage of flight, on airplanes considerably more complex than the average light plane. Now, the best of us occasionally miss items, but that's what the checklist is for. Another tool we have to help us remember the procedures are flow patterns.

A flow pattern is simply a logical pathway across the panel or panels that will guide you to the systems that need reconfiguring for each phase of flight. Each phase of flight will have a different flow pattern, but they often follow roughly the same order. Here's a picture of the First Officer's "Before Start" flow pattern on the Megawhacker:

If you asked me to name each of the fourteen items that the Flight Standards manual says I should accomplish before start, I could rattle them off to you - not because I memorized a list of procedures but because I can visualize the flow pattern and know which systems it leads me to and in which order. Obviously, this works only because the flow pattern follows a logical, linear path. If it had me jumping all over the panel, it'd be worthless and I might as well remember the procedures by how they're listed in the FSM.

The airlines have full-time flight standards people to put together and revise flow patterns, procedures, and checklists. You can do it for the airplanes you fly, though. You can develop your own flow patterns, checklists, or both. The goal is to come up with something that you like and that you find easy to use consistently, and keeps your eyes out of the cockpit for more time than the system you're using now.

You'll typically design flow patterns for the following phases of flight: before start, after start, before takeoff, after takeoff, approach, before landing, after landing, and parking. I suggest you work out the flow patterns either by sitting in your cockpit or using a high resolution picture of it. For each phase of flight, trace an easy-to-remember "trail" that connects each item that needs to be checked or reconfigured in an order that makes sense. Memorize each "trail," thinking about which items you would be touching, checking, or moving along the way.

Here's a sample Before Start flow I put together for the Cessna 150:

You start at the lower left corner of the panel with the master switch (turn it on) and work your way counterclockwise. This directs you to the electrical panel (CBs in, lights as required), trim (set), throttle quadrant (throttle & mixture set for altitude & type of start), flaps (up), radios (off, ELT armed), flight instruments (clock and altimeter set) and finally back down to the lower left corner (prime as appropriate, then in and locked). You would then read a simplified Before Start checklist that ensures the major items for the start have been accomplished.

Master Switch-------ON
Lights--------------AS REQUIRED
Mixture------------ SET
Primer--------------IN & LOCKED

Note that this checklist says nothing about flaps or trims even though it's in the Before Start flow. That's because you'll also be checking them in the before takeoff flow, and then they're in the Before Takeoff checklist. You keep the checklists short and usable by including only items that are applicable to that phase of flight, even though you may be taking care of "housekeeping" items ahead of time in the flows.

The C150, like most smaller piston singles, is simple enough that you can use the same flow pattern for most phases of flight. For example, imagine how the above counterclockwise flow would cover approach items: lights set as appropriate, mixture set for density altitude, ATIS received and radios set, altimeter and DG set, primer in and locked.

I remember using an abysmally long before start checklist for the PA28 that was actually a do-list and went so far as telling you, step by step, how to start the engine. The engine on the PA28 really isn't that complicated to start - you don't need to include simple memorized procedures like this on your checklist. Now, there may be more complicated variations that you don't use often - hot or flooded starts, for example - and it's perfectly acceptable to include these on your checklists as designated do-lists.

Certain time-critical emergency procedures are memory items both in GA and at the airlines. For an engine failure at low altitude, for example, there is a procedure you should have memorized and be able to execute within seconds. These memory items should have associated checklists that can be accomplished if time permits to make sure that the appropriate actions were taken. Any emergency checklist that does not back up a memory item should be used as a do-list. If you don't have a good emergency checklist for your airplane, make one - the emergency checklists in the Pilot Operating Handbooks are typically inadequate and usually inaccessible anyways. Keep yours in a handy place and make it visible - I suggest pasting the checklist to hot pink card stock and laminating it.

Flow patterns and checklists used as checklists aren't completely foreign to General Aviation: most of the structured Part 141 training programs use them from Day One, as do more progressive FBOs and independent CFIs. If you've never used this method, I suggest you give it a try. It makes good cockpit discipline a whole lot more palatable.


Ron said...

Well said. So many GA checklists are miles long, which only encourages people to skip items, get lost while performing the checklist, or just do away with the list altogether. Keep it short and simple.

I'm also a big believer in using the checklist as a checklist, not a do-list, whenever possible. To do otherwise makes flying so cumbersome that the temptation to just do things "from memory" is quite strong.

I haven't seen many people who are dogmatically attached to traditional do-list checklist techniques. But every now and then I do run across one. One guy I recall, in particular, had every screw, nut, and rivet listed on a checklist for preflighting the airplane. And sure enough, he read each item, did what it said, and then hunted for the next item on this 10 page monstrosity.

Must have taken him 30 minutes to look over the plane. Ugh.

Even short and sweet checklists are no guarantee, however. I was flying with a student in the Extra 300 the other day, and it was hot so he left the canopy open until ready to start. I don't have a problem with that -- it can get up to 150 degrees in there really quickly. The canopy comes down right before start, even though closing it is at the top of the "start" checklist. Well, you can guess what happened: he started to crank the engine with the canopy open before I could say anything (I'm strapped in the front cockpit, facing away from him). But I yelled "STOP!!!" so loud that it went over my head, through his headset, and over the sound of the cranking engine.

Replacing an EA300 canopy is a $15-20k affair.

Fred said...

Sam, you've done it again: written a post worthy of printing to read with a cup of coffee. Thanks.

Anonymous said...

I came by this tonight and plan to pass it by my daughter who is learning how to fly. I started with flows from the first day I ever stepped into a PA28. One flow did pretty much everything from starting the engine to dealing with an engine out. Since then I've taken the same ideas to PA28R and other aircraft. I guess it's what happens when your first CFI moonlights as a Lear captain (or maybe it was a Lear captain moonlighting as a CFI).

Anyway, thanks for the great post from "someone other than dad". She will find it in some obvious place and maybe I'll get to see her stop flailing around the cockpit when life gets "busy".

D. Patrick Caldwell said...

I do agree that checklists are better than do lists, but I think do lists are better than memorizing the list and checking your work afterward.

I think that's how pilots get complacent and very experienced pilots end up skipping steps (sometimes disastrously).

Now, I'm not a highly experienced pilot, but I do actively seek the opinions and techniques of others to boost my flying skills. I was looking for opinions on checklists to write about on my aviation blog and I've discovered something really interesting. There are a lot of medical posts about checklists.

It turns out, the medical field is adopting the do-list strategy of checklist-ing because it is so effective. I wouldn't really be all that keen on a surgeon flow-patterning through my body ensuring that she didn't leave anything important in there.

I wrote a post about a time I got distracted in the middle of my GUMPS check and I missed an item because I didn't use my checklist. Everything turned out okay, but even a simple checklist would've helped me avoid some embarrassment.

I still use the GUMPS mnemonic, but usually just as a mental comfort confirmation. I always use my descent and approach checklists. If I don't have time, I shouldn't've let myself get so far behind the plane.

I may be one of those sticklers people talk about, but it strikes me that memorizing a checklist is a little like memorizing an approach plate. I'd much prefer to work through the approach plate like a do list that like a checklist.

One thing to keep in mind is that it's possible to configure the airplane and then get distracted and to say, "well, the checklist is really just a check anyhow." A do list would verify that you're unprepared.

Just a thought. What do you think?

Sam said...

DPC, you're right that a do list is preferable to simply memorizing the checklist...memorizing checklists does encourage one to simply skip the real thing afterward. Flow patterns, on the other hand, are about following the geography of the cockpit rather than reciting a litany on paper. Their use does require a firm commitment to checklist usage. Fortunately, this commitment is a lot less burdensome than that associated with a do-list. I think the reason so many GA pilots are lax about checklist usage is because of the cumbersome checklists they used in training and the distracting manner in which they were trained to use them. If more were trained to configure the airplane using flow patterns before running a simple, short checklist, a LOT more would use the checklist religiously.

Your basic point about using some sort of checklist at all times without fail stands, though. Even in simple GA aircraft, it's quite easy to miss something important when distracted.

checklistguy said...

Hi to all

this is a very insightful topic, and the replies so far have been great... though for airline flying (I am a junior airline guy) I do have some concerns with "memorizing"

in our operations here, we also do the flow system... it is good for when the airplane is already moving, however, during preflight setup, our company trains us to setup the airplane by using the flow system on its own ONLY... which means not using any preflight procedure/checklist to crosscheck that everything is on its proper place...

for example - on the 747/777, the preflight setup, from the overhead to the center pedestal is always being done solely by memory... we are even forbidden, sometimes, to use the amplified preflight checks on the QRH to verify setup accuracy... and to further emphasize this potentially dangerous practice, practically every controls setup for critical airplane systems are on the amplified preflight checks...

I do agree that do and verify cockpit practices are an efficient way to manage cockpit work, but if one would say that memorization is a good way to go here, (or just using the cockpit flow, without a means of crosschecking stuff), then we are setting ourselves up in trouble..