I've noticed on some days there is an EXTRA assistant with the refueller, and usually dressed in white overalls. This guy usually operates a small valve that seems to come from a separate tank, however the hose from this separate tank connects to the main refuelling hose.. .. .Almost uncannily the day AFTER I have seen this man in white, our passenger loads are chokker block full. I've also noticed that whenever WE fly through another aircraft's contrail, I get this URGE to want to travel forever.. .. .Funny that!