This question involves
‘backwards use’ of the reference lines …
NORMAL use of the REF
LINES means you go to the REF LINE … then adjust to the condition.
Backwards use of the REF
LINES …. To the CONDITION FIRST, then adjust back to the REF LINE.
So for this question, we
need altitude …
Work normally with
DISTANCE and WIND, draw a line straight through the
ALTITUDE section.
Now work backwards with
FUEL and LW … enter at 15000kg, straight across to 50000kg LW condition, now
adjust down to the REF LINE. BUT, which curve do we use – we need to know
altitude – so guess to start with – use a ‘mid’ line, half way between 37000ft
and 10000ft (23000) … this takes me to one grid square above the 14000kg line …
now draw a line straight through the altitude section … the 2 lines intersect
at 17000ft.
Now we could go back and
adjust our LW correction to reflect 17000ft … (we guessed 23000ft) … this would
bring it 1˝ grid squares above 14000kg … answer 16500ft?? (but
looking at the answers, there isn’t really a need!)
Wasn’t that fun!!!!!!
There are a few of these “BACKWARDS” questions in the exam system.