Optionally piloted vehicle

An optionally piloted vehicle (OPV) or optionally piloted aerial vehicle is a hybrid between a conventional piloted aircraft and an unmanned aerial vehicle (UAV). Able to fly with or without a human crew on board the aircraft, OPVs are a low-cost alternative to UAVs in research, experimentation, and concept exploration, but may also become used in mainstream operations as familiarity with them increases.

Source: Wikipedia — Optionally piloted vehicle (CC BY-SA 4.0)