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or leave someone behind. If you take
the same fuel anyway, you will be
overweight, with not enough power
in the engines to get you out of
trouble, and invalid insurance.
You will need more power to
counteract the effects of ice. Fuel
flow will also have to be adjusted if
you use specialised equipment in
flight, such as heaters, or not use
anything essential, such as an engine.
Don't forget, on the exam, that you
have to calculate fuel for the
alternate as well as the destination.
Fuel and oil consumption rates and
weights for flight planning should be
in the Flight Manual. It's usual to
keep a check on the fuel contents to
see if things are going according to
plan, thus keeping track of fuel
consumption.
When it comes to flying bigger
machines, however, fuel planning
and management becomes much
more critical. When heavy at the
wrong level, you could be burning an
uneconomical amount of fuel
relative to what you would burn
when lighter at a more sensible level
– jet engines are that sensitive. The
weights of fuel carried can make
significant differences in airspeed
and/or performance as it is burned
off, but this is covered more under
The Cruise (under Performance), below.
The main thing to bear in mind is
that your weight at the end of a leg
will be a lot different than that at the
start of it, and so will the fuel flow,
which changes in sympathy. You
therefore have to get used to making
educated guesses as to the mid-leg
weight to get a mean fuel flow.
Helicopters
Helicopters don't need aerodromes,
and minimum figures reflect this.
However, they are calculated for
level aircraft. Odd attitudes, say
when slinging, may cause a fuel
boost pump to become uncovered
and give you a nasty surprise just
when you don’t want it. On a 206,
the unuseable fuel after a boost
pump failure can be up to 10 US
gals, which is uncomfortably close to
the minimums.
You must be able to fly for 20
minutes at normal cruising speed
after reaching your destination. For
IFR and night VFR, it’s 30 minutes.
Fixed Wing
The plan should be to arrive over
the destination in a position to make
an approach, overshoot and fly to an
alternate, and still have enough to
hold for 45 minutes (30 if a turbo
jet) at the alternate. Even then, you
must still be able to carry out an
approach and landing, so you should
carry enough for the estimated time
to the destination, plus 5% for
contingencies, time to alternate, and
holding fuel.
Flight Planning 327
IFR
Journeys are split into specific
phases, such as start, checks, and taxi
(that is, before take off), take-off and
climb (another phase), cruise and
descent (yet another), approach and
landing, plus 10%, plus missed
approach and diversion to the
alternate. Then there's holding at the
alternate, unuseable and contingency
fuel, which covers errors in forecast
winds, navigation, ATC restrictions
and individual variations from
standard fuel consumption. By
arrangement, block figures can be
used which ignore the take-off and
climb. In fact, headings required are:
· Start, taxi and run-up (plus icing
systems and APUs)
· Departure and enroute climb
· Route fuel, to include climbs
· Approach
· Missed Approach
· Alternate fuel
· Reserve
· Contingency fuel
Point of No Return
This is the furthest point you can fly
to and return to your point of
departure, based on a given amount
of fuel, which usually, for obvious
reasons, takes account of a certain
amount of reserves (so-called "dry
tanks" PNR is not a good idea). After
the Point of No Return, you do not
have enough fuel to return home on
a navigation leg, hence the name. It
is purely a fuel problem, having
nothing to do with distance, so if
PNR is beyond the destination, so
much the better. The formula below
can also give you a patrol time, in a
radius of action problem, which is just
the same thing, really (the edge of
the radius is your limit if you want to
use the same fuel to get back to base,
quite useful in the Arctic, over water,
or in similar hostile territory).
If you have to calculate this after an
engine failure (in real life, not the
exam), refer to Specific Ground Range,
below, and add the fuel used per
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Canadian Professional Pilot Studies2(77)
