The right-seated pilot’s failure to correct the left-seated pilot’s mismanagement of the engine thrust, which resulted in undesired speed and thrust oscillations during the final approach and a subsequent descent into terrain.

The pilot's decision to land the fully loaded parachutist drop airplane on a wet grass runway that had insufficient length for the landing in high temperature conditions, which resulted in a runway overrun, when a more suitable longer runway was available at a nearby airport.