Airdrops from military cargo planes are not always performed at high altitude, as the one showed in the spectacular video posted a few days ago.
LAPES (Low Altitude Parachute Extraction System) enables cargo aircraft to quickly deploy large cargo without the need to land and take off, which would expose the plane to enemy fire. The technique is also used to deliver those heavy loads that could not be delivered from high altitude with a direct parachute descent.
However, since LAPS involves a drop sequence at low altitude it implies a heightened risk as there is little margin for pilot error.
As the following video shows.
It was taken on Jul. 1, 1987, 26 years today, when a U.S. C-130E crashed while performing a LAPES demo at the Sicily Drop Zone, on Ft. Bragg during a Capabilities exercise (CAPEX).
Pilot pulled up too late and after deploying M551 Sheridan tank, hit treeline, burned, killing three on board, one soldier on the ground, and injuring two crew.