The ski jumpers changes his position in the air during all phases of the jump. He tries to use the aerodynamic forces of the air. The equipment also has its influence on the aerodynamic.
In order to find out the best position in the inrun and during the flight, the teams make tests in wind tunnels. In opposite to a jump on a hill, the athletes there have various minutes to test various positions.
An aerodynamic position in the inrun is important in order to reach a high inrun speed, during the flight-phase it's about using the aerodynamic forces of the air in the best way possible.
For example the position of the arms and skis are having an influence on aerodynamics during a jump.