I think the answer to the OP's question is "not really much of a problem at all", however if you do it, even though in reality its almost certainly no big deal, the oil companies will go ballistic!
Therefore we do have various SOPs to prevent it, but it still happens just occasionally when its least expected, and as always its a combination of rare and unfortunate circumstances that leads the crew down the wrong path.
My only personal experience was back in the days of the S61 (1981 I think) where we were going to a semisub under tow. Popped out of cloud in the aprox location where the semisub should be by now, there it was, landed on it but oops, there was another one a couple of miles away also under tow, which was the correct one. How unfair was that! Fortunately in those days less of a fuss was made!
It would of course help if the rig's name could be read without having to nearly crash into the structure to see it - hidden behind all those pipes and hoses and covered in bird poo and rust.
Last edited by HeliComparator; 3rd Feb 2013 at 23:03.