Chugalug2
I can only recommend that you do some homework on this system off thread – ask colleagues/contacts just how it was used – come back and enlighten us.
Answering your points for the benefit of other readers in the meantime and not really wanting another deluge from you:
The handset is a UHF radio and transponder – factory calibrated, it is intrinsically accurate and either transponds or it doesn't as opposed to giving an inaccurately timed return – same as for on board kit – works or it doesn't – if you are getting consistent returns of the right order (say, in rough agreement with a STANS or what you could visually judge) then you would expect it to be very accurate such that you could forget about the STANS and your fuzzy visual judgement and concentrate on the readout.
Plus it is a radio – the operator on the ground can talk directly to the pilot – as you can so clearly hear helos approaching, you could be standing halfway up the hill in mist but pulling the pilots leg about it being clear on the LZ and you can see them and their approach is fine, etc..
If they had been doing a fast approach but were misled as to their range to go, they could reasonably have expected to have been down to a speed at which the pilots and the loadmaster could have clearly seen the shoreline by the time they got there as opposed to its whizzing past unexpectedly.
They would not have been at fault if they were misled as to their closing range by a third party on the ground using this equipment.
For those of you wondering about about ½ mile extra being sufficient for slowing down enough to actually land there, bearing in mind there was a 30kt tailwind and, while within the capabilities of a Chinook with an experienced crew, there would not have been need to demonstrate the equipment by landing, especially with the passengers on board – just a tight turn at 60kts right over the LZ would have been impressive enough – hence the H-B track aready being set up – just turn around and head NW until picking it up.