Flight Training - March/April 2025 - 22

PREFLIGHT FLIGHT LESSON
BY CHRIS GRECO
SILENT AND DEADLY
A CARBON MONOXIDE ENCOUNTER
TEST / RESET
ALERT / STATUS
WHAT HAPPENED
We were about five miles from the airport
when I noticed a warning light.
Carbon monoxide is produced as a
REAL PILOT STORY
MY HELICOPTER INSTRUCTOR ASKED ME WHAT I WANTED TO DO
for the lesson, and I responded that I would like to practice
autorotation procedures and basic maneuvers. We decided to
start with a short cross-country and were about five miles from
the airport when I noticed a warning light. I mentioned it to the
instructor, who immediately recognized it and acted to prevent
something that could affect us both.
The warning light was labeled Carbon Monoxide (CO). This
is something that is covered in the knowledge tests and pilot test
prep, but rarely comes up in real life, at least not as dramatic as
looking at a bright light telling you there is a tasteless, odorless
gas in the cockpit that can kill you.
The instructor commended me for seeing the light and
started to open the vents, shut off the cabin heat, and turn on the
cabin air. It was evident he was doing the right things, including
waiting a few seconds after the corrective actions to ensure the
light was not just being finicky or was broken. The CO light had
activated before, but only for a few seconds. In all, the entire process
from identifying the light to deciding to turn around back to
the airport took one minute. The reason I am so sure about the
time is that I had a camera in the cabin that recorded the entire
incident. We turned back to the airport, and I predicted the light
would go out after we landed, which it did.
After we landed my instructor found an issue with the
exhaust line, which he reported and helped to prevent any
further incidents. It seems that the Robinson R22 doors were not
used much until recently because of the warmer weather, which
is why it hadn't been a problem on recent flights.
22
FLIGHT TRAINING MARCH/APRIL 2025
'HIDDEN HAZARD'
The AOPA Air Safety
Institute's Real Pilot
Stories allow pilots to
share their encounter
with a dilemma so
others can benefit-
while comfortable
on the ground-from
lessons learned the
hard way in flight. In
Hidden Hazard, pilot
Dan Bass reflects on
a haunting flight in
his Mooney when he
was overcome by
carbon monoxide
poisoning and lost
consciousness while
airborne.
airsafety
institute.org/
RPS/HiddenHazard
byproduct of exhaust emissions from
engines, and helicopter engines are no
different. The NTSB recommended
requiring carbon monoxide detectors in
airplanes and in helicopters in 2021 after
a review of accident reports identified
31 accidents attributed to carbon monoxide
between 1982 and 2020 resulting
in more than 40 deaths. The idea that
such a little molecule could cause havoc
made me realize just how important it
was to understand and combat this type
of danger.
The lessons that I learned from this
incident are three-fold. First, always
check the warning lights and gauges. It
is drummed into your head during each
flight to do a landing or maneuver check,
but it should be done as part of your
normal scanning. I just happened to be
looking at the warning lights when the
carbon monoxide warning light came on.
Call it luck, but I hope it was just part of
the routine scan. Second, practice a carbon
monoxide warning emergency so that
you can do the corrective measures by
heart. Third, and final, this incident raised
my alertness to the carbon monoxide
problem and to not treat it like something
that one can just ignore until it goes
away. The light is there for a reason. I am
hoping that I never have to take corrective
action again but knowing what to do is the
first step in knowing when to do it. If the
light is lit, you must commit.
CHRIS GRECO is a private pilot with more than
200 flying hours, with over 40 hours in the
Robinson R22 helicopter. He has been flying
periodically since 1972.
TOP LEFT: ALEX WILLIAMSON ABOVE: STEVE KARP
http://airsafetyinstitute.org/rps/hiddenhazard http://airsafetyinstitute.org/rps/hiddenhazard http://airsafetyinstitute.org/rps/hiddenhazard
Flight Training - March/April 2025

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