AOPA Turbine Pilot Magazine - August 2019 - 82

AOPA

PILOT
GUIDES
THE ONLY COMPLETE RESOURCE
FOR FLYING THE ISLANDS

P&E

PROFICIENCY

During the ILS approach back to
MDQ, I lost the left engine and before I
could say a word, Mr. Clyde presented
another scenario. "Ever hear of pilots who
fear turning from the departure leg of the
pattern to the downwind leg? How can
you make sense of that?"
"Identify...Oh sure, I've heard of the
notorious 'downwind turn.'
"Verify..." I told him I believe the best
explanation of both the erroneous thinking
behind it as well as the truth is presented
by pilot and author John Denker on his
website See How It Flies (av8n.com/how).
"Feather." As I secured the Seminole's
left engine and set up for the instrument
approach I explained the scenario used by
Denker: Suppose that a one-ton aircraft
climbs away on the departure leg at 100
knots true airspeed into a 20-knot direct

My spirits sank with
the thought that,
while I had passed his
quizzes, I may have
failed my multiengine
instructor practical
exam.

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headwind. The speed over the ground is
then 80 knots. By the time it turns to the
downwind leg, the groundspeed soars to
120 knots.
The gain in kinetic energy (half the
mass times the speed squared) needs
to come from somewhere. The airplane
must experience an enormous energy
deficit during this turn and is, therefore,
closer to a stall. At least that is how the
argument goes.
Denker continues to explain that this
erroneous line of thinking ignores the "bat
effect." A baseball that hits a wall gains no
energy in the process. But when it hits a
fast-swinging bat, it gains a significant
amount before it soars toward the outfield.
In the flight scenario, the airplane plays the
82 | AOPA PILOT August 2019

role of the ball and the wind is the swinging bat. Without wind there is no change in
energy from the departure leg to the downwind leg. But the 20-knot wind supplies
the extra energy that increases the groundspeed of the airplane. It's the same energy
increase we enjoy as we travel cross-country with a strong tailwind. To avoid a stall
in any turn, take the same precautions one
does in an ordinary no-wind situation.
"The moral of the story is to relax, don't
worry about it, and go with the flow," I
explained.
After a smooth landing, I taxied the
airplane in front of the FBO and went
through the after-landing shutdown procedure. As we removed our headsets, Mr.
Clyde said with a sigh, "You know, I was
trying to distract you during that flight."
Before I knew it I blurted, "Oh but, compared with my kids, you aren't very good
at it." On occasion my mouth moves faster
than my brain and, with that remark, Mr.
Clyde finally got the sterile cockpit he was
seeking all afternoon. Why didn't I tell
him to be quiet earlier? My spirits sank
with the thought that, while I had passed
his quizzes, I may have failed my multiengine instructor practical exam. After
a pause that seemed to last forever, he
chuckled, suggested that we keep those
conversations to the classroom, and
motioned me toward the FBO where he
wrote up my temporary certificate.
Two years ago, the world lost a treasure when Mr. Clyde passed away, but I am
reminded of his lessons often. As a designated examiner myself now, I often smile
inside when candidates instruct me during the preflight briefing to abide by the
sterile cockpit rule-as I have no intention of doing so. Their future passengers
are bound to break this rule, and I need to
ensure that the pilot can handle such a situation appropriately. Of course, we should
firmly ask our passengers who interfere
at critical phases of flight to keep quiet. I
learned this and so much more from the
master himself.
AOPA
CATHERINE CAVAGNARO is an aerobatics

instructor (aceaerobaticschool.com) and
professor of mathematics at Sewanee: The
University of the South.
http://www.av8n.com/how http://www.aopa.org/pilotguides http://www.aceaerobaticschool.com
AOPA Turbine Pilot Magazine - August 2019

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