Friday, March 04, 2005

Cute But Useless Mnemonics

In continuation of my checklist rant, I present my complaints about checklist mnemonics, the little acronyms people stuff into their heads and recite at crucial moments in aviation. They have their place. Sometimes they are great. Sometimes they are misapplied, and sometimes they were poorly devised in the first place.

The most common is probably GUMPS:
Gas - correct fuel tanks selected
Undercarriage - landing gear up or down as appropriate
Mixture - full rich for sea level take-offs and landings, leaned in cruise
Propellers - full fine for landing, lower rpm for cruise
Switches - fuel pumps, magnetos, landing lights, heater, whatever

Likely half a dozen people are looking at this saying things like, "No, no, Aviatrix. The P is for pumps." However you say it probably attaches to the airplane you were flying at the time you learned it, and whatever that was had its own unique set of prelanding and after takeoff tasks. That in itself is not a problem, and if you have mapped the letters to tasks that are required for your aircraft, and those tasks properly associate with the letters in your mind, well GUMPS away and I won't even give you a dirty look.

But the trouble begins when the words don't properly associate. For North American pilots half the time the GUMPS recitation stands for Gear, Um ... The only time many pilots here would refer to the landing gear as "undercarriage" is during a GUMPS check. It's more of a British word. Which is odd, because gas for fuel is more of an American thing. Most pilots say fuel. Look at Kristopher, the student pilot who inspired this posting, saying "I had to ask the instructor to remind me what 'P' and 'S' stood for." So here's the poor guy, smart enough to program computers for a living, and instead of just memorizing a sequence of prelanding checks, he has to memorize it in association with a nonsense word. If you can't remember something, sure, use a mnemonic. But if the mnemonic is harder to get right than the task?

And then there's the fact that Kristopher is flying a fixed gear aircraft with a fixed pitch propeller. That means that (a) the gear is welded permanently in the down position and cannot be raised or lowered in flight and (b) the propeller is one solid piece of metal and the angle of the blades cannot be adjusted. So what is he using GUMPS for? If he has been advised to say, "Gas: fullest tank, Undercarriage: already down, Mixture: full rich, Propeller: still going around, Switches: fuel pumps on, landing light on," then no wonder the sequence was difficult to learn. If his instructor has twisted GUMPS to align with the tasks that actually have to be completed before landing, then good, but will those associations stick in a complex airplane, causing him to neglect gear and propeller levers? Probably not, because the appropriate lights and levers will be in plain sight. I'm not sure what the use of the mnemonic is when being in the airplane tell you what to do.

Mnemoniccs get worse, though. I've seen CCCC recommended for an overshoot checklist.
Cram - the mixtures, propellers and throttles
Cowl flaps (and/or carb heat)
Call and advise ATC
Presumably at some point in here you remember to get the flaps and gear up, too. CCCC is useless, because there's nothing in the mnemonic to put the tasks in the very essential right order. Raise the nose before adding power and you may not be doing much climbing.


Kris Johnson said...
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Kris Johnson said...

FWIW, I was told that 'P' was "pump" and 'S' was "seatbelts." I agree that this is a silly way to try to learn important procedures.

I'm memorizing the mantra "mixture, pump, tank, gauges, seatbacks and seatbelts, flaps" which are the steps in my school's official pre-landing checklist. I can't come up with a pronounceable acronym for it, but I think learning it this way and visualizing the flow will be a lot more useful than some nonsense word.

Another popular-but-misleading mnemonic is "A TOMATO FLAMES," which lists the equipment the FAA requires to be operational for a flight. Unfortunately, this acronym provides a generic list, and the actual requirements will vary by aircraft model. It was a lot easier to just memorize the list of required equipment in my airplane's operating handbook.

Lost Av8r said...

I try to use the checklist as much as I can, rather than try to remember silly mnemonics. I still, however, use TILTFF:
Ignition/inertial seps

I find that after a good couple of months of flying that the checklist is so engrained in my memory that I would need help to forget it.

Anonymous said...

There was once a companion to this for pre-takeoff: CIFFTRS

Seat Belts

It's also said that there was once a military training flight where the intercom failed. The instructor was trying to get the student to do his pre-landing checks, so he shouted at the top of his lungs, "GUMP! GUMP! GUMP!" The student, ever obedient, jumped. (Bailed out.)


Anonymous said...

As for the four Cs, I heard it later in my piloting career. However the version I heard did cover the necessary things and in a more reasonable order.

Cram (power)
Climb (pitch)
Clean (drag, flaps/gear up)
Cool (cowl flaps)

Unknown said...

I have been taught the BUMFHH method.

Mixture rich
Fuel selector on

Anonymous said...

Moronic Nitwits Eventually Memorize Oddball Nomenclature If Cognizance Slacks