If conditions are normal and a green light is shown, the athlete's coach – who is situated in a coaches' section lower down the inrun with a flag in hand – gives them the final signal to go; coaches may sometimes have to whistle or give a shouted confirmation in low-visibility conditions. Once given this signal, the athlete must commit to their jump within ten seconds or else risk disqualification, and are no longer permitted to exit the gate. To begin descending the inrun, they drop down from the gate to a crouching position. Speed is rapidly picked up within seconds via built-in tracks, made from porcelain or ceramic, into which the skis are slotted. The athlete's streamlined crouch minimises air resistance along the inrun, and a further effort is made to reduce friction by not allowing the skis (which have wax applied to them) to bump too much against the sides of the tracks. Inrun speed is measured from the table using a radar gun.