Interesting topic for sure. This March I was flying NW from AMS-JFK on a 747. The entire business class section in front of the Economy section was empty. I think they did not have that many passengers in Business and moved everybody to First since the whole sections was clear; or maybe they had seated everyone in another section upfront. It was not an equipment change (the original booking said 747 though individual configurations may be differnet). Incidentally economy was packed.

You could clearly see the empty cabin from your coach seat since the curtains were not drawn. From my seat in economy the film screen in business offered the best view of the movie!

I was wondering why NW did not move some passengers over from economy to business (just for seating); they could have kept the same food/drinks service. There were no business class passengers anyway, and a lot of passengers were connecting via AMS from flights from Asia. I personally had another 8 hour flight from DEL before the AMS-JFK connection. Would have loved the extra space and the chance to relax rather than being stacked in coach, which did not have a single empty seat. I think NW lost a chance to earn their travellers goodwill here. On AA I know of cases (3 cabin 767 on domestic routes), where all the elites are seated in the business section on coach fares, since they do not normally sell business seats on those segments.

Makes me wonder what would have happened if I had sneeaked in to snooze in the business class seat. After all it was not that I was expecting better service of anything, just a little more space on the 20 hour journey. Would it have been unethical or was it justifiable?