Has anybody ever noticed that PW-engines smoke a lot more than GE's or RR's? Seeing a 747-400, MD11 or a 777 with PW's take off is like watching a Tu154M!!! (Not that I have any objection to smoking planes!! :-) )
In Amsterdam we have Martinair operating PW MD11's and 767's, and KLM operating GE MD11's and 767's... You can sure see the difference! I know smoke is no indicator of fuelconsumption or pollution. The real polluters like SO2 and NOx and such are invisible. But I can imagine that to a passenger that has no knowledge of engines and aircraft it would be a bit of a worrying sight!