Apparently, the solution to this is retrorockets -

Once clear of the plane a single large main chute opens. The deployment of the main chute triggers the deployment of four long rods which hang beneath the pallet. As soon as the rods touch the ground fires, slowing the BMD to a descending speed between 6 m/s and 7 m/s and giving it a relatively soft landing. This system entered service in 1975 and allows a BMD to be relatively safely parachuted with both the driver and the gunner.