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accidents so, unless you feel the
aircraft will be uncontrollable, your
chances may better in the air.
Charts
These may look complex, but once
you've figured out the way to enter a
performance chart, it becomes
considerably easier. For exam
purposes, the best tip is to read the
small print around the graph itself, as
this is where you will find the
conditions on which the chart is
based, such as "generator off", or
"ant-icing on".
Here is an overview of a typical
performance chart:
It's kept deliberately clear so you can
see the basic procedure more easily
(they have loads more lines on
them). Essentially, it's a combination
of several graphs in one, each one
feeding off the other, and a typical
flight manual has a miniaturised
version to show you what goes on.
Flight Planning 353
Usually, to take landing distance
required as an example, you start
with something like your landing
weight against Pressure Altitude, go
from their intersection to
temperature deviation, then runway
slope, then the wind component to
find your answer. Note that, very
often, you have to work backwards,
or at least go through the process
several times to get what you need.
For example, in the above case, you
most often need to know how heavy
you can be to fit into the runway at
the other end.
Excellent examples are in the
Transport Canada Study Guides.
Height/Velocity Curve
Otherwise known as the Dead Man's
Curve, this is a chart for helicopters
that compares speeds against heights
to give you an idea of where not to
be if you want to make a successful
recovery from an engine failure, that
is, you don't want to be at high
altitudes with low speeds, or low
ones with high speeds, so the best
place to be is in the gap between the
shaded areas. In other words, the
graph shows combinations of speed
and height that the average pilot
would find it impossible to make a
safe emergency landing from. To
give the average pilot more of a
chance, a one-second delay is
factored in for minimum skill levels.
A couple of points to note first of
all: one is that you should check to
see if the chart is in the Limitations or
Performance section of the Flight
Manual (the BK 117's moves to the
limitations section once you go into
high density seating). If it's in the
latter, its requirements are
recommended, not mandatory. You, as
a licence holder, have enough
knowledge to exercise your
judgement, and the chart is there as a
guide to aid you in that process. In
some circumstances, it is more
dangerous to try to avoid the curve,
especially if you might only be in it
for a few seconds (as when getting
out of a confined area, for example).
Another is that it is not necessarily
valid for approaches, being
calculated for level flight (see below).
Some helicopters, like the TwinStar,
sometimes don't have one at all.
Anyhow, the vertical shaded area in
the diagram above is called the low
speed section, which is actually split in
two parts at the knee of the curve,
although it's never shown (the knee
is the furthest point at which the
curve extends). The lower portion is
for takeoff power (no intervention),
and the upper portion is for level
flight (cruise power, hand not
necessarily near the collective, so one
second allowed for intervention
time), and the whole area will
expand with Density Altitude. On
approach, you have your hands on
the controls and are using less than
cruise power, so the same figures
don't work.
The other shaded area is the high
speed section, and the clear area
between them is the takeoff corridor.
Takeoffs and performance
calculations should take account of
354 Canadian Professional Pilot Studies
the curve, which is constructed at
maximum weight, with no wind at a
density altitude of at least 7,000 feet.
Those of lesser quality must be
verified (that is, actually flown) by
the relevant Authority.
V-Speeds
Significant aircraft speeds, on large
aircraft, calculated for every takeoff,
and varying with weight or mass.
Some, like V1, are found in tables in
the Performance section of the
Flight Manual. Typically, you would
enter a table at the appropriate PA,
then go across until you reach the
relevant temperature range (making
sure you use C or F). Then apply
gross weight and flap settings and
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