AIS shows intense activity around Garths Ness which is a rocky headland west of Sumburgh at lat/long 59.884/-1.355 or grid HU364111.
The activity shows a pattern flown west of the Ness then activity along the shore including three returns to Sumburgh including one recently. The aircraft concerned is on MMSI 2161 which is one of the Bristow S-92 in CG colours (R102) and I believe may be G-MCGC. Currently on the ground at Sumburgh.
Another track shows the Lerwick lifeboat which left Lerwick at 1745UTC and left similar tracks to helicopter and is now steaming back past Horse and approaching Sumburgh Head.
The RO-RO vessel has also just left the scene where it had been steaming loop all evening south and west of the ness.