STOL to ISC
Hi Phileas
I think the jetfoil is an interesting red herring. I don't know enough of the subject to make any sensible comments. My only thoughts apart from the initial costs and the lack of winter traffic is that the harbour at St Mary's may not have enough depth of water at all tides. The present vessel can only berth there as it is shallow draft and flat-bottomed. I'm guessing that a jetfoil would be more expensive than an additional Twotter or two.
I think your SOU/BOH comparison is relevant. However, if SOU closed, there would be no alternative to BOH. The heliport at Penzance is a five minute ride on a dedicated mini-bus service/800 metre walk from the station. Lands End is pretty remote. Its worth mentioning that the car-park at the heliport is usually packed to capacity with several hundred cars during the summer meaning that there are those willing to drive considerable distances. I think that the attraction, and boasting rights, of going on holiday by helicopter should not be overlooked.
Most people seem to agree that the dash7, while technically capable, is not a profitable option, a view supported by the fact that it has apparently never worked the route. From local knowledge I know that there is a high percentage of visitors who not wish to use the sea-route and I think that they will continue to fly even if they have to trek to Lands End. If you have driven from Bristol and further east and north, another ten miles is unlikely to be a problem. There will no doubt be an increased bus service PZE station to Lands End.
How the S61 will compete with the Twin Otter under equal conditions remains to be seen. Again worth mentioning, the S61's have a GPS/NDB IFR approach into ISC which was specific to type and approved crews and which the fixed-wing did not use in my time. Not to say that they couldn't.
Interesting to see what happens in 2012