CFI-to-CFI Newsletter - Volume 10 Issue 4 - 6

If you release the parking brake, it will start
rolling down the hill, even though the engine is
not running. In the same way, if your airplane
has excess altitude, you can trade that altitude for
airspeed by pitching the nose down, effectively
tapping into that stored energy. The reverse is also
true. Excess airspeed can be traded for altitude by
pitching the nose up. If you think of it in financial
terms, thrust represents your income, drag
represents your bills, airspeed represents your
cash flow, and altitude represents assets such as
money in savings accounts, etc.
Let's look at the example of flying aerobatics.
If you begin a loop without sufficient energy, as
you approach the top of the loop, you will run
out of energy. You could fall out of the loop, or
even slide backwards on your tail, known as a
tailslide. With many aerobatic airplanes such
as the Citabria-in level flight at full throttle-
you will not have enough airspeed to begin
a loop. You often have to dive and accelerate
to a higher airspeed before beginning the
maneuver. If you are performing a sequence
of aerobatic maneuvers, you need to evaluate
your energy state at the end of each maneuver
before beginning the next. Airspeed and
altitude are both part of that equation. If there

isn't sufficient altitude and airspeed, you will
have to break off the sequence and climb before
resuming the sequence.
APPROACH AND LANDING

Now let's think about the application of these
principles during approach and landing. Would
you want to approach for landing at just a couple
knots above stall speed? Probably not, since
such a slow speed gives you no margin above
stall speed to account for wind gusts or poor
technique. Stalling the airplane at low altitude is
hazardous to your health.
On the other hand, would you approach to land at a
speed just a couple knots below redline? If you tried
to flare to land at such an outrageously high speed,
you would have so much excess energy that you
would float into the next county before the airplane
would be ready to land! Running off the end of the
runway is likely to ruin your day, or worse.
Think of it this way. The stalling speed might be
thought of as representing the point where you
are out of energy, because the airplane no longer
has enough airspeed to sustain level flight. When
you compare the manufacturer's recommended
approach speed versus the stall speed in the

landing configuration, you will typically see a
20 to 30 percent margin above stall speed. This
represents reserve energy to help protect against
an unintentional stall. It also represents energy
that must be bled off during the flare to land.
Until that reserve energy is used up, the airplane
will float down the runway. This manufacturer
recommended approach speed is a good balance
between too little reserve energy and too much.
When flying the recommended approach speed,
you will have some float during the flare, but it
shouldn't be excessive.
Some pilots get into the habit of automatically
adding 10 or 20 knots to the recommended
approach speed, perhaps because of fear of
stalling. Arbitrarily adding extra speed is not
good energy management. When you calculate
landing distance from the manufacturer's Pilot
Operating Handbook (POH), it is based on
using the recommended approach speed.

IF YOU TRIED TO FLARE TO LAND AT
SUCH AN OUTRAGEOUSLY HIGH SPEED,
YOU WOULD HAVE SO MUCH EXCESS
ENERGY THAT YOU WOULD FLOAT
INTO THE NEXT COUNTY BEFORE THE
AIRPLANE WOULD BE READY TO LAND!
CFI-to-CFI Newsletter - Volume 10 Issue 4

Table of Contents for the Digital Edition of CFI-to-CFI Newsletter - Volume 10 Issue 4
