Friday, April 10, 2009

I Can See Clearly Now


One of my favorite teaching techniques is not in the syllabus, but lots of instructors do it: find some aviation-related event a reasonable distance away, load up an airplane with students, and fly there. The students get a little extra practice with cross-country flying, they get to fly near maximum gross weight, they get to fly with an aft (but legal: I have them check) center of gravity, and we always have a good time.

One of my students asked about attending Dr. Michael Crognale's seminar on vision and flight, and suggested flying there. He liked the idea of taking someone else along, and plans were made.

The plans did not include the thunderstorm sitting along the route of flight. This was going to make things interesting.

We met and went over the weather. Destination and departure were forecast to be good VFR for the rest of the night, with showers in the vicinity. There was no weather forming behind the storm, and I ran my finger over a route that would miss the storm but get us there.

In my mind, this is "real world application of Aeronautical Decision Making." But this is a mouthful of educational jargon, which is usually a sign of trouble.

But that's when I did the smart thing. "Some airlines have a rule," I said, "that the most uncomfortable pilot makes the decision. Who's the most uncomfortable about this weather?"

This takes discipline: if I had been alone I would have flown. But the teaching point was more important than the flight.

"Call me chicken, but I don't like it," one said. "You've always said not to trust the forecast too much, just like on our cross-country." His long dual cross-country had involved a weather diversion, which was fine by me. Otherwise I would have had to make something up to force a diversion.

"Do you want to drive?"

"Yes."

So we drove. In his car.




The seminar was fascinating, and I highly recommend it. A few years ago I was involved in an image processing research project, so I thought I knew a lot about vision, but Crognale was knowledgeable and entertaining at the same time. He included a lot of fun demonstrations of the effects of accomodation on what we can perceive.

One take-away point was about cockpit lighting. Everyone's eyes react differently to color, and red lights really bother some pilots. His recommendation is to shorten the wavelength of the cockpit lighting as little as possible to make you comfortable; that is, try orange, then yellow, etc. But in any case, never use blue-green lighting; that destroys the most night vision, because of the response curve of the rods. Even white is better than blue-green.

I stopped carrying a red light a long time ago, and use a trick I learned reading Fate is the Hunter. I hold the flashlght between my fingers, and just let a small slit of light through. A lot of the light has to go through the webbing between my fingers, which means that the light I use is yellow-orange, an acceptable wavelength.

His explanation for the prevalence of blue-green cockpit lighting was as a spin-off from the requirements of military pilots wearing night vision goggles, but I'm not so sure. The King Airs I flew had blue-green cockpit lighting, and their design long predates NVGs. The King Air lighting always bothered me. I could turn off one of the panel floods, the worst offender, but there was still plenty of blue in the cockpit. And, I could never turn the lights down as far as I liked.

I was also reminded about a conversation I had with my eye doctor a few years ago. Referring to IFR charts, I said that I had trouble reading small print in dim light.

"Then don't do it!" he exclaimed. But I had no choice.

What I have yet to try is reading one of the charts I keep in my iPhone at night. These are mostly white, with some brown tints, but I'm afraid that the phone will be too bright and ruin my night vision. Oh, hey, this is an excuse to go flying some night soon!

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