There are several theories represented in this thread, if you have read through it. What I will say is that in the years that we have been staying at Beachside Villas--5 or 6 years now--I have seen several planes take off the 'wrong' way. I have NEVER seen KLM 747 (or Corsair before they stopped flying 747's) take off the 'wrong' way, so the 'heavier' theory is not correct, I don't believe.