Enter on
TRIP DISTANCE scale at 2400 NM … go vertically up to the WIND REF line – make a
pencil mark ...
... adjust to 25 kt TAIL WIND condition … so follow the adjustment curves down
and left to 25 kt TAILWIND … make a pencil mark … now draw a line vertically UP
through the 2 sets of PRESSURE ALTITUDE curves.
From the first set of PRESSURE ALTITUDE curves … find 31000ft (interpolate
between 29000 and 33000) … from this point, go right horizontally to the
LANDING WEIGHT REFERENCE line … make a pencil mark.
Now adjust to the LW condition 52000kg … there are 2 curves … the dashed line,
which you would follow IF you were at 37000ft, and the solid line, which you
would follow IF you were at 10000ft … so you need to interpolate between the
two. This is a bit of a fiddle – but if you just draw both adjustment lines
(37000ft and 10000ft – the interpolation will become straight forward – look at
the answers – the spread is quite reasonable.
For trip time, go to the TOP PRESSURE ALTITUDE curves … 29 & ABOVE … across
to the ISA DEVIATION REF LINE - make a pencil mark … now adjust to your condition
ISA-10⁰C, so right and up to ISA -10 … now read the scale.