If the engine quits between Sumburgh and Foula or a few miles past it and your at say FL 75 at least you have dry land to aim for or get as close too.
You should try Tingwall / Lerwick EGET - its a nice and challenging little airstip.
It is my local airstip and they get allot of people like you flying into it.
Its NDB is 376.0 and "Tingwall Information" is on 122.600Mhz
I should also mention there are 3 Search and Rescue Helicopters based at Sumburgh so at least if you do have to ditch between Sumburgh and Foula, you will be picked up pretty fast
Cheers,
Shetlander
