Wednesday, October 27, 2010

Darn Clab, Bard Calm

Reading Matthew May's In Pursuit of Elegance got me thinking about how, try as we might to keep things simple, aviation tends to be a complicated activity. Many GA aircraft have a peculiar steam punk sort of appearance when compared to the simplicity of modern automobile designs. Perhaps the lack of progress in simplifying aviation designs has to do with the very regulations that are supposed to ensure aviation safety. Compare a non-IFR-certified handheld GPS receiver with an IFR-approved panel mount unit: The handheld units generally have simpler user interfaces while the panel mounts seem needlessly complicated. But it's not just avionics that complicate the picture. Instrument approach procedures, with the advent of RNAV, have certainly gotten more arcane. The promise of FADEC notwithstanding, GA pilots routinely fly behind aircraft engines produced with the latest manufacturing techniques, but based on designs from the 1950's that require more user input and a lot of monitoring. In the face of research that shows the human brain is not very well-suited to monitoring, pilots, instructors, and the FAA recommend procedures like checklists, flow checks, and mnemonics to help manage the workload and remember to do important stuff.

Checklists & Do Lists

Every practical test standard (PTS) publication from the FAA contains the phrase "... completes appropriate checklist ..." Not just once, but several times. Typically checklists contain a series of tasks grouped by the phase of flight - preflight inspection, engine start, taxi, before takeoff, and so on.

A checklist can be used as a "do list," where a pilot completes one item at a time, in sequence. Some instructors teach pilots to read the check list out loud in a single-pilot environment. In multi-crew environments, one pilot may read the challenge part of the task while the other pilot responds after the required action has been completed. Checklists need to be used intelligently in single-pilot operations, which is why the FAA included the following language in the Instrument Rating PTS:
The situation may be such that the use of the checklist, while accomplishing elements of an Objective, would be either unsafe or impracticable, especially in single-pilot operation. In this case, a review of the checklist after the elements have been accomplished would be appropriate. Division of attention and proper visual scanning should be considered when using a checklist.
That's good advice, though I'd change the word "should" to "must." In any event, what the FAA seems to be suggesting is that the use of a flow check or mnemonic is called for during high workload situations, after which the pilot can use their checklist to verify that they haven't forgotten anything.

Go with the Flow

A flow check is a procedure where a pilot sets aircraft controls in a particular sequence that follows the layout of the controls, thereby making the position of the controls a reminder to the pilot of what to do. The flow check may or may not group the actions to be accomplished in the same exact order as the checklist. A flow check is not foolproof because as your attention shifts to each gauge or control, you must take the appropriate action and take notice of any abnormal or emergency conditions. When using a flow check in single-pilot operations, you'd best to back it up with a real checklist when time permits.

Becoming a (Wo)Man of Letters

Mnemonics are memory devices that can help a pilot accomplish a sequence of tasks from memory when they don't have the luxury of picking up and reading a checklist. I've taught many of the common mnemonics (like CGUMPS and the five T's), even though I'm not necessarily fond of some of them. My teaching experience has shown me that to be effective, an acronym needs to be catchy and it should contain unique letters that spell out some recognizable word. While no mnemonic is perfect, correlating a series of tasks to a string of identical letters requires more mental effort. And if the same letter is used multiple times, the order of the tasks is more likely to be mixed up in the heat of the moment. Consider the following two mnemonics for an approach briefing.

M - Missed approach
A - Altimeter(s) set
R - Radios set, Nav & Com
T - Time from FAF to MAP
H - Heading on intermediate and final approach
A - Altitudes at FAF, stepdown fixes, DH or MDA

A - Altimeter
A - Airspeed
A - Approach speed
A - Avionics

I've seen pilots make more mistakes with the five A's, the five C's, and the five T's. I've seen pilots unintentionally omit one of the items. Just as often they confess that they know they are forgetting something, but are only able to recall the first letter of the item.

Of course, which mnemonic works for you is up to you. Here's a mnemonic that seems to harken back to an era when smoking was more commonplace. I don't use it, but some pilots swear by it.

C - Controls, free and correct
I - Instruments, left to right, top to bottom
G - Gas set to fullest tank, auxiliary fuel pump
A - Altimeter set
R - Radios, runup completed
T - Trim(s) set for takeoff
I - Interior, doors and windows secure
P - Propeller full
S - Seatbelts, switches

Lastly, here are some memory devices I learned from Lou Fields, a Naval aviator who returned to civilian life in the late 1960's and has been an instructor and designated examiner at the Oakland Airport for as long as anyone can remember.

This is Lou's before takeoff check for an IFR departure:
D - D/G, De-ice
A - Airspeed, Attitude Indicator Altimeter
R - Radios
N - Needle & Ball

C - Clearance, charts, cockpit
L - Lights
A - Altimeter error
B - marker Beacons

And here's Lou's instrument approach checklist.
B - marker Beacons on
A - ATIS recorded
R - Radios set
D - Directional gyro checked/set

C - Clock
A - Altitude error noted
L - Landing check completed
M - Missed approach briefed

In single-pilot operations, it's obvious that mnemonics have shortcomings similar to flow checks: You best back-up a memorized list of tasks with a checklist.

Mistakes Still Happen

After a long day of flying behind glass panel aircraft, is it any wonder how some pilots might yearn to fly a taildragger made of wood and fabric, with a few simple controls and the minimum compliment of instruments? The problem is that even in a simple aircraft a pilot with good checklist discipline can still make critical mistakes. There are steps pilots can take to reduce these risks and I'll cover that in my next installment.

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