Simplify the following text for a Grade 9 native English-speaking person.
Original: Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne .
Simplified: Gliding is an activity and sport in which pilots fly unpowered aircraft known as gliders or sailplanes using rising air to stay in the air .