Subhadrika Sen
Circle with extended fingers: Join the tips of your thumb and index finger to form a circle and extend the other three fingers outside. This mean OK.
Cross palms: If you extend all five fingers of both your palms and cross them against each other, you would be signalling someone to STOP.
Overhead fist: Curl all five fingers into a fist if you want to signal someone to WAIT.
Thumbs up: Use the universal thumbs-up sign to denote that you are ready to ASCEND.
Thumbs down: This signals that you want to DESCEND.