In the 70s we lived on the Forties Field using a Bolkow for mainly inter platform changing. The rigs are similar & at night or in poor weather it was hard to see the platform. The Doppler often would drop off line on those short legs & so the procedure was to call on final & get a positive landing clearance. The system worked well as I must have done well over 10000 landings without a problem, sometimes 120 a day or night but I can see how easy it could be to land on the wrong platform. I feel sorry for that crew as I'm sure that dung will come their way!