If there is no upper deck bridge then loading by lower deck only would lengthen loading and unloading process. Normally upper deck passengers, no matter what class, use the upper deck bridge. Lower deck passengers us the lower deck bridge. It is just like a normal plane but with two floors. The airports have the solution with the double level bridges. The old 747's with the spiral stair cases were the tricky ones, the 744 had a straight and wider staircase so much better. Boarding concerns regarding the 380 I find tend to be myths, was on
SQ 833 from
PVG-
SIN last Saturday, sat at 78G upstairs economy rear of plane, flight was full. Boarding was done in about 30 to 35 mins and getting off was about 10-15 mins. Both
PVG/
SIN have three bridges for the 380.