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place, and that these rules are
approximate, because altering
heading changes the relationship of
the wind to your machine.
Departure
For the most accuracy when learning
to fly, it is best to get to a safe height
over the departure point, then set
course, making sure you pass the
start point in the cruise. Although
this means you won't have to make
separate calculations for the climb,
with more experience, you will be
able to climb away on course directly
from the circuit, making the proper
allowances.
En Route
Accurately fly your planned heading
for six minutes, note your position,
then compare it to the map, and the
10 nm intervals you drew on it.
Whatever distance you have flown in
six minutes multiplied by ten is your
groundspeed, so 10 miles in 6
minutes is 100 kts. You now have
either confirmation of planned
groundspeed or a new one, so you
can create a new ETA.
Check your DI against the compass
every 15 minutes or so. Also, check
your fuel state against your progress,
noting large reductions in particular,
as they may indicate that you have
left the fuel cap undone, or that you
have a leak.
The Circle of Uncertainty
Assuming you have flown as
accurately as possible, and the wind
velocity was accurately forecast, and
you made no mistakes in your flight
planning, you should find yourself
pretty much on track throughout the
flight. However, life is not always
like that, and once in a while you
may find yourself unsure of your
position, which is the technical term
for being lost.
The circle of uncertainty is a way of
trying to remedy this by allowing a
percentage of error and drawing a
circle of appropriate size centred on
your destination. In theory, you
should be somewhere inside it. Its
diameter will very rarely be more
than 10% of the track distance.
Map Reading
Get used to recognising ground
features from the map and angles
and distances between them. When
Navigation 151
identifying a fix, you need at least
three ways of confirmation.
Also get used to not necessarily
needing to know exactly which field
you are over at all times – a common
fault is too much accuracy when you
start flying. Knowing you are so
many miles in a particular direction
from somewhere is good enough.
If operating inside a particular area,
choose a prominent landmark and
rotate round it, that is, keep an eye
on your position in relation to it.
Check Features are prominent
landmarks selected in the planning
stage to look for during the flight.
The span of your hand is about nine
inches, very useful for measuring
distance. From the middle of your
thumb to the tip is about an inch.
Some Questions
1. How far will you fly in 2 hours 38
minutes at a groundspeed of 364
knots?
2. If an aircraft flew 60 nm in 14
minutes with a TAS of 250 kts, what
is the wind component?
3. With a wind velocity of 260/15
and a track of 296°T, what heading
and airspeed should be flown to
maintain a groundspeed of 120 kts
on track?
152 JAR Private Pilot Studies
Some Answers
1. 960 miles. Line up 60 against 364
on the outer scale, then look for the
answer against 158 minutes.
2. Line up 14 on the inner scale
against 60 on the outer, to read the
groundspeed of 257 kts against the
60 triangle. Since this is more than
the TAS, there is a 7 knot tailwind.
3. 292° at 132 kts.
Flight Planning
This may appear tedious in the early
stages, but planning is actually
around ¾ of a trip. The more you
do, the more answers you will have
to hand when things go wrong and
the better the trip will be, as any plan
you have spent time over is better
than one cooked up on the spur of
the moment. If you get yourself into
a little routine, the process will
become speedier as time goes by.
Proper Planning Prevents Poor
Performance.
Well begun, half done.
Points to remember are the weather
details for the destination and
alternates, plus takeoff alternates if
you have to land back in a hurry (this
could mean up to eight airfields),
check the runways available (and
crosswinds!) and NOTAMS, in case
any aids are out.
Sometimes ATC have preferred
routings. Check the altitudes on the
chosen route, and ensure you have
the performance to maintain them –
adjust your all-up weight.
Always ensure you are using the
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