Nav computer: in the
AIRSPEED window place the temperature (-30ºC) next to the Mach No. Index, go to
Mach No. (0.83) on the inner main scale and read TAS next to it on the outer
main scale: 503kts)
Put 60 minutes on the
inner main scale next to 503kts on the outer main scale, go to 360nm on the
outer scale and read time (42.9 mins) next to it on
the outer scale. N.b. zero wind so groundspeed =
TAS.
Aircraft needs to cover
360nm in 47.9 minutes (5 minutes longer than planned).
Put 47.9 minutes on the inner
scale next to 360nm on the outer scale; go to 60 (minutes) on the inner scale
and read required groundspeed/TAS on the outer scale: 451kts.
In the AIRSPEED window
place the temperature (-30ºC) next to the Mach No. Index, go to TAS 451kts
on the outer scale and read Mach No. next to it on the inner scale: M0.74.