Five judges produce a score for air and a score for form. Air is covers the takeoff, height and distance and is scored out of 2 points (why height and distance are not objectively measured, I have no idea). Form is the body and skate position in the air, scored out of 5 points. The air and form scores of each judge are added together, then the high and low scores are discarded.
Two judges score the landing out of 3 points. The average of the two scores is multipled by 3.
For example, Zongyang Jia got 6.1, 6.4, 6.5, 6.6 and 7.0 for his first jump’s air+form. His combined air+form score = 19.5. He got 2.6 and 2.6 for landing. His landing score = 7.8.
Air+form and landing are added together and multiplied by the degree of difficulty. The difficulty is based on breaking the jump into components. The latest scoring seems to give extra difficulty for twists done earlier, but this Ski Federation manual is almost right.
Aerials ramps are so steep that you can only start with a back-flip, so every jump starts with the word “back” (difficulty = 2.0).
All Olympic-class jumps are done in the layout position because the smaller profile means you can twist faster. So the simplest jump is a “back lay” (difficulty = 2.05).
All male Olympic jumpers do triple-flip jumps. Five people in the world have done quadruple-flips, but the risk of landing on your head makes it illegal in competition (aerials has a lot of safety regulations). Each flip is divided by a dash, so the simplest Olympic-class jump is a “back lay – lay – lay” (difficulty = 3.3)
For each flip, you can do from 0 to 3 twists. One twist is described as a “full”, two as a “double full”, three as a “triple full”. I wish more competitors did half, 1.5 (a “rudy”) and 2.5 (a “randy”) twists to mix things up. Thomas Lambert is the only qualifier who regularly does half twists, such as his “back half – randy – full” (difficulty = 4.525).
Most competitors do a total of 4 twists over 3 flips: a quadruple jump. The 2002 gold medal was won with a quintuple jump but Anton Kushnir (DNQ), Jeret Peterson and Warren Shouldice are the only people who have done 5 twists in competition this season (not always successfully). The most difficult jump ever is a “back double full – full – double full” (difficulty = 5.0).