Helicomparator
Thinking back I can highlight two of my best fails , one significant and one maybe more illuminating. Remember the (Laybarge 234?) Had a deck with side flaps that had to be raised like a gateleg table. Not knowing that (long before helideck manuals and diagrams became the norm) and on my first flight to it after it arrived, we got there to see this rectangular and long but narrow helideck which we promptly landed on, or rather along, unloading and loading through the cargo door as the airstair door was unusable due to edge proximity!.... Only later did we hear that they had raisable side flaps, we had been given landing clearance and thought that was just the way it was. The transit crew expected us to call for the flaps if necessary, but they had only been used to much smaller beasts that the S61. Its companion laybarge was even worse with the deck being between the various structures and the only approach was at right angles to the heading of the barge.
On deck identification, after a short notice request by Ekofisk to do an inter rig shuttle for them on a day long ad-hoc trip, we spent a lot of time and fuel looking for the 'Henry Gibson' as Ekofisk got more and more frustrated with our inability to see it, until the penny dropped it was the 'Henrick Ibsen' and we just didn't connect the name ...... Red faces all round. The final touch on that trip was a landing back into Aberdeen off the ILS in a reported 300 meters RVR (which was our limit at the time - hand flown, no holds, no autopilots ) and then literally having to follow the taxi lines to find the apron. Some trips you never forget.