From the Coll and Colonsay NOTAMs:
ALL AIRCREW AND PILOTS MUST WEAR HI-VIZ WHEN AIRSIDE
and
PPR WILL NOT BE GIVEN TO ANY ACFT IF ETA/ETD WOULD CONFLICT WITH SKED MOVEMENTS
Strange [NOT] that no such strictures apply at the Orkney strips, almost all of which have far more regular scheduled services.
Perhaps the Highland Airways pilot has recently failed an eyesight test.
NS