In 1998, the McDonnell Douglas AV-8B Harrier II was the only fixed-wing vertical/short takeoff and landing (V/STOL) aircraft in the free world. Its ability to take off vertically makes it one of the most maneuverable combat aircraft in service, and it can zoom out of the range of enemy fire extremely quickly. The AV-8B Harrier II Plus, with a more powerful engine and advanced radar and avionics, can operate efficiently in darkness and in adverse weather conditions. Currently, the U.S. Marine Corps is converting all its day-attack Harrier IIs into Harrier II Plus aircraft.