[thehappypm]

Gliders don't launch by winch. They are towed up to launch height by powered planes.

Also, gliders are not really able to handle emergencies that well since they are unpowered -- if there's a need to divert or something, they're completely at the mercy of their own gravitational energy. Gliders are usually very safe to fly in because they're very light and maneuverable, and crash-landings are usually OK. That safety net completely evaporates with thousands of pounds of human cargo.