This Site is dedicated to all those families of the people that have tragically disappeared on flights in and around New Zealand. I only hope that from all the effort in building this site and from all the effort of those taking part in this venture, that it will bear fruit in bringing ‘closure’ to their memories!
Gavin Grimmer
The above shows the VHF (line of sight) radio reception area at 7800’(green areas)
- just 300’ higher than shown on the previous image (previous page) and so you can
see how precise it is to calculate what height Roy was likely to be at when he made
contact with Hokitika. Go a little higher and there would have been no problem with
reception. Go a little lower than 7500’, and no reception with Hokitika until clear
of Mt Adams.
According to information I have, ZK-CSS was a Cessna 172K model (1969-1970 model)
and it had a cruise speed of 114 knots at 9000’.
It is not known what the wind speed and direction was through the Godley Valley that
day, although the observer inland of the Whataroa Bridge said there was no wind,
and it was also reported that there was no significant wind at Tekapo at the time
the Turners departed , so it appears Roy was ahead of the approaching front. It is
then possible to calculate Roy’s ground speed reasonably accurately , but just to
be sure, we will calculate a likely ground speed using a range from 100 knots to
125 knots to allow for a possible head wind, or tailwind:
100 knots = 1.66 nm covered per min (14 knot headwind)
110 knots = 1.83 nm/min (4 knot headwind)
114 knots = 1.90 nm/min (advertised cruise speed)
125 knots = 2.08 nm/min (16 knot tailwind)
25 minutes @ 100 knots =
41.66 nm (25 x 1.66)
@ 110
knots = 45.83 nm
@ 114
knots = 47.50 nm
@ 125
knots = 52.00 nm
If we then place these distances on his possible track, this is what we get:
You’ll note that the “still air” cruise speed (114 knots) fits the bill perfectly
as it puts the position of ZK-CSS at 7500 feet just inside the first reception area
which covers a distance of 1.34 miles and at 114 knots means it was in coverage for
up to 42 seconds...long enough to get a call to Hokitika, get a call back, and get
a off a request for the weather.
