"Jay Honeck" wrote in message news:pPtqd.410498$wV.201320@attbi_s54...
Many of us cold-weather pilots worry about carbon monoxide in the cabin,
especially in winter. After using the "dot-that-changes
color-on-a-piece-of-cardboard" carbon monoxide detectors for the last 9
years, we decided to look at the new battery-operated detectors.

Last year I made a foray into this field by buying a Wal-Mart home model.
It turned out to be too big for use in the plane, and had an alarm threshold
that was set too high.

That's a common problem in the U.S. Fire departments complained about
too many call outs so the feds limit the thresholds. I bought mine
from a firm in the U.K. and have been very happy. I did have a real
life CO emergency and was very happy to have had it. I was surprised
that...

1) Turning off the heater DID NOT lower the CO level enough for
survival. With the heater on I was getting about 1500 ppm near my
head. With it off I was still getting around 800ppm.

2) Opening the pilot window did make a big difference, bringing my
near head level to about 200ppm (that is within Cal OSHA's tolerance
for an 8 hour work day).

3) This happened after take off at night in dark IMC. I heard the
alarm. I'm sure there would have been no way I'd have noticed a
sticker changing color while coordinating with ATC in dark IMC.

4) With the digital gauge I was able to quantify my problem. Without
it, I'm not sure what I would have done. I wouldn't have had any way
to determine the level of severity.

-Robert