Gavin Grimmer
This seemed entirely possible and so I worked out a scenario that he flew over Mt Aspiring – a peak that is easily identifiable, the highest in the area, and not prone to be mistaken for another peak. He then flew over Homestead Peak, lined it up with Niger Peak and took a compass bearing. Then overflew Niger Peak and descended down through the cloud into the Wanaka Basin.
This scenario seemed to be confirmed by a Mr Lamp (Report 34) who was climbing Mt
Iron near Wanaka at noon and “saw the aircraft heading towards Motatapu Valley”....
Note he “SAW”.
Mt Aspiring – HEARD... Mt Iron – SAW!
This means that between Mt Aspiring
and the Motatapu Valley, they somehow got down through the cloud.
Unfortunately,
Mr Lamp of the White Elephant Hotel, Wanaka has by now probably passed on? If anyone
knows of him and he is still alive, I would certainly like to talk to him to find
out precisely what he saw – if he can still remember!
This seemed a very feasable
explanation of where and how Chadwick got down below the cloud, until I remembered
that his original magnetic compass was found still in his office/workshop (LOST page
159)!
He had however installed a Piper Autonav Radio Compass (otherwise known as an ADF -Automatic Direction Finder). He may have had another compass fitted, but there was no record of this.
AUTOMATIC DIRECTION FINDER
ADF (Automatic Direction Finder) is the radio signals in the low to medium frequency band of 190 Khz. to 1750 Khz. It was widely used today. It has the major advantage over VOR navigation in the reception is not limited to line of sight distance. The ADF signals follow the curvature of the earth. The maximum of distance is depend on the power of the beacon. The ADF can receive on both an AM radio station and NDB (Non-Directional Beacon). Commercial AM radio stations broadcast on 540 to 1620 Khz. Non-Directional Beacon operate in the frequency band of 190 to 535 Khz.
(Copied from: https://www.thaitechnics.com/nav/adf.html)
Although it says the ADF signals follow the curvature of the Earth, due to the mountain range in between, the ADF could possibly have been all but useless on the West Coast, although Colin Tuck informs me that there was 3ZA AM Station at Greymouth with a transmitter at Kumara Junction 12 miles north of Hokitika. However Colin also said they used to listen all the time to the AM station at Dunedin from Fox Glacier in those days – so who knows?
Now that I have remembered that he had this ADF installed, it alters everything.
He
didn’t need a compass heading. He only needed a position.
Hence I now believe he positioned
the aircraft over Niger Peak and followed the direction shown on his ADF tuned into
the AM Radio Station at Dunedin. Being at a fairly high altitude over Mt Aspiring
would have made it easy to get a signal strong enough to do this. An ADF is not restricted
to only Navigational Aids (Nav-aid) but to any transmitting station within the AM
bandwidth that the ADF is capable of.
The observers at Mt Aspiring in Report 42, thought
it left the area heading south towards Shotover (presuming they meant Shotover Saddle)
but it could have easily have just been circling back from there towards Niger Peak?
They did however say “generally south” in the direction.
Without being able to speak to these observers and get answers to all the questions I would like to ask them, I am at a loss to explain it all, but often I have found it is more of a case of knowing what they meant – and not what you think they meant... if that makes sense?
However, this doesn’t alter the fact that Mr Lamp claimed he saw an aircraft at noon
heading towards Motatapu Valley, and although when I wrote my book “TRACED ...yet
still missing!” I had envisaged Mr Lamp seeing a plane flying south across Lake Wanaka
towards that valley, whereas now it appears he saw it in the distance flying east
towards it.
Paul Powell’s witness account said the cloud base was at around 6000 ft,
so assuming that the base was the same in the Wanaka Basin, this is what I think
Mr Lamp saw:
Of course the cloud base is never as depicted in this image (that is all Google Earth
will allow) I think he saw an aeroplane popping in and out of banks of cloud heading
towards the Motatapu Valley which is behind the hills shown just to the left of the
arrow.
Often it is possible for a pilot flying towards the base of the cloud, to think
he is still in solid cloud as everything outside the windscreen is white, whereas
in reality, people on the ground – looking up through a thin layer of cloud, can
see the plane.
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