This past Sunday, I noticed something unusual at SFO: instead of a plane taxiing by itself all the way to the gate, they stopped the plane just before entering the gate area, and had a tug pull the plane into the gate itself. This happened to the flight my stepfather returning from Hong Kong arrived on, Singapore Airlines Flight SQ002; they stopped the 777-300ER first, then had a tug pull the plane into Gate G91 on Concourse G at the International Terminal.
Does anyone know why this is was done? Was it done as a fuel-saving and pollution-reduction measure? Or was the spacing around Gate G91 so tight with a 773ER they decided to use a tug for easier placement of the plane into the gate parking spot? I've noticed that when the SQ 773ER parks at the gates further out into Concourse G they don't do this practice, and the 773ER taxis by itself all the way to the gate.