I was talking with a prospective instrument student this morning who, like most, was concerned about approaches. His home airport has three approaches, one VOR-DME and two RNAV, and I know that his airplane isn't equipped for the RNAV approaches. But that's irrelevant: approaches are the last thing he needs to worry about now.
Teaching instrument scan is one of the most challenging assignments I have ever faced. I've tried all sorts of things and maybe there are a few I haven't tried. The diagrams in the FAA Instrument Flying Handbook are of some use, but they can't duplicate the dynamic nature of the situation. One instructor impersonates a metronome, and the student is supposed to look at a different instrument at each tick. Another takes a pencil and taps each instrument in turn, saying "Look here!" "Look here!" "Look here!" (This one works pretty well, actually.)
When I was at my sharpest as an instrument pilot (alas, that was a while ago) I noticed something strange. The perception/reaction sequence seemed to get reversed. Typically, you would expect that first a needle would move, and then you would perceive the movement during your next pass around the panel, right? But when I was at my sharpest I found that I would look at an instrument and then it would move. (This isn't just me; I've heard this from others.) I used to tell my students that that was the goal for being instrument sharp.
I couldn't explain this. It couldn't be that my body sensed any motion, because I had pretty rigorously trained myself to tune out somatic stimuli. How did I know that the needle would move just before it did?
I think I have an answer, and it is going to sound quite strange and mystical, but I assure you that it is pretty solid science. You can read more in the April 25, 2011 issue of The New Yorker; the article is by staff writer Burkhard Bilger.
This explanation depends on two widely-recognized principles: first, the brain takes in more information than our conscious minds can process, so it selects what we attend to; and, second, there is some delay between an event in the world at large and our perception of that event. David Eagleman, a neuroscientist at Baylor University, studies the nature of consciousness, and has spent a lot of time trying to measure the interval between event and consciousness as well as what happens during that interval. This isn't filling cranial cavities with beans: he is using functional MRI to map the regions of the brain that become active in response to certain stimuli.
The short version is that the brain constructs a story around all of the data the senses bring in and merges all of this sensation data into the story. So here's what happens in instrument flying. Say that the airspeed starts to rise but you are conscious of gazing at the altimeter. Your brain perceives the change, and you travel back in time to the instant before the change occured, directing your consciousness to the airspeed indicator. Well, no, you don't travel back in time, but you don't travel ahead in time as quickly as you usually expect. A good neuroscientist like Eagleman could set up an experiment to see if the pilot's eye really moves to the airspeed indicator, or whether the change of conscious focus happens internally.
Instrument training teaches the brain that the airspeed needle movement is important and requires a change of focus, while the corresponding movement of the second hand on the panel clock is of no consequence and therefore should not be brought to attention. When you get it, it doesn't matter which instrument you focus on. Your brain perceives them all, and will let you know when one of them does something important.
If this is correct (and even I have my doubts) then it doesn't matter whether the instructor uses a metronome or a pen or a series of strings going from instrument to instrument that looks like some impossible cat's cradle position. What matters is that the instructor makes the brain attend to the instruments and that the student spends enough time practicing to lay down the neural pathways.
Our society likes speed, and you can certainly find accelerated this and superfast that. I've always had my doubts about accelerated training, though. I think it produces a different kind of knowledge than the slower variety produces. I'm not saying that the knowledge is inferior; in fact, it can be quite useful. But one has to understand that some kinds of knowledge just take time. National Football League coaches say that it takes 20 to 25 games before a new quarterback has the game "slow down" enough in order to make him effective; it's the same kind of thing.
My prospective student told me that he would like to fly every other week for some reason I couldn't quite follow. No matter.
"You'll never finish the rating at that pace."
Learning fades unless it is repeated, and two weeks between practice sessions is too long for an adult. The neural pathways would fade rather than be reinforced.
And every flight instructor knows this. Students who fly infrequently, at every level, drop out. You can speed things up a little (4 or even 5 flights a week), but not too much, and you just can't slow things down.
Even if you can travel backward in time.