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and 30% when wet (it's not
348 Canadian Professional Pilot Studies
recommended that you operate
when the grass is over 10" high).
For dry short grass (under 5 inches),
the LDR will increase by 20%, a
factor of 1.2. When it's wet, 30%—a
factor of 1.3. For dry, long grass (5-
10 inches), LDR will increase by
30%, and 40% when wet. For other
soft ground or snow, the increase
will be in the order of 25% or more
for take-off and landing.
Obstacles (The Climb)
Takeoff requirements also need to
consider obstacles along the take-off
path which cannot be avoided
visually. The area concerned is a
funnel extending up above the
airfield from the end of the TODR
within a distance either side of track
(with all engines operating). The Net
Flight Path is made up of segments
covering various stages of flight
(such as when undercarriage or flaps
are raised) and is so called because
NET (i.e. factored) performance
data is used to assess it. The NFP
commences from 35 feet above the
end of the TODR, this being the
imaginary screen the aircraft must
clear. This point is known as Reference
Zero, which is where the takeoff
officially ends and the climb begins,
at V2, in fact.
The various stages of a climb are:
· The first segment starts at
Reference Zero and ends when
the gear comes up. Transport
category aircraft must be able to
climb positively during it.
· The second segment lasts until
when the aircraft is levelled off
for the cleanup (usually 400 feet
AGL, with speed at V2, flaps
and power at takeoff settings
and the propeller of the failed
engine feathered).
· The third segment ends when
ready for the enroute climb,
usually a level burst at 400',
during which acceleration is
made to Vyse, flaps are retracted
and power is reduced to Max
Continuous (there is usually a
time limit for the engines).
· The fourth (and final) segment is a
climb to 1500', or higher if there
are obstacles. The aircraft is
clean with Max Cont power on
one engine, the other feathered.
Maximum climb performance in
most jets is achieved at a constant
IAS until a specified Mach number,
which is held constant until levelling
off in the cruise.
Flight Planning 349
If an obstacle (including a frangible
one) intrudes on the Net Flight Path,
then take-off weight must be
reduced until it's cleared by the
relevant margin, so this may be a
determining one in calculating
Restricted Takeoff Weight (see above).
You can make gentle turns to avoid
obstacles, and not have to fiddle
with take-off weights, and there will
be graphs in the Flight Manual
allowing you to calculate radii and
procedures for it. However, you will
need to be visual as well, so a
minimum cloudbase is necessary.
If an engine fails in the climb out,
normal practice would be to return
to the point of departure, but if you
can't (maybe the weather) the NFP
and MSA must be examined at the
flight planning stage. It may even be
necessary to climb overhead the
airfield to get the height before
going for your return alternate.
You must use the one-engine inoperative
net flight path data from the point at
which full instrument flying
commences, or is expected to.
The best Rate of Climb speed is
obtained when there is the greatest
difference between the power
required for level flight and that
available from the engines. In
turboprops, this will coincide with
the speed that gives the best
lift/drag ratio, since power output is
relatively constant. Turbojets,
however, produce more engine
power with speed, which is enough
to overcome the extra drag, so the
maximum differential between
power required and available
happens at a higher speed, and best
ROC occurs above L/DMAX. There
will be performance tables to find
time and fuel required for climbs.
Remember that headwind and
tailwinds will change the distance
figures. To cope with this, work out
the groundspeed with no wind and
apply the corrections then. You can
use the whizzwheel to find out the
distance and time.
The Cruise
That part of the trip from the top of
the climb (TOC) to the top of the
descent (TOD), when the Captain
wakes up. The idea is to use the least
amount of fuel, if only because some
airlines increase your pay packet, but
sometimes, you must get to a point
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