Hawker Siddeley Harrier to the pilot by a head-up display and a moving map display. The Harrier's VTOL abilities allowed it to be deployed from very small prepared clearings or helipads as well as normal airfields. It was believed that, in a high-intensity conflict, air bases would be vulnerable and likely to be quickly knocked out. The capability to scatter Harrier squadrons to dozens of small "alert pads" on the front lines was highly prized by military strategists and the USMC procured the aircraft because of this ability. Hawker Siddeley noted that STOL operation provided additional benefits over VTOL operation, saving fuel and
Harrier Jump Jet to proceed with ordering a modified derivative of the P.1127/Kestrel for service, which was designated as the Harrier GR.1. The "Hawker Siddeley Harrier GR.1/GR.3" and the "AV-8A Harrier" were the first generation of the Harrier series, the first operational close-support and reconnaissance attack aircraft with vertical/short takeoff and landing (V/STOL) capabilities. These were developed directly from the Hawker P.1127 prototype and the Kestrel evaluation aircraft. On 18 April 1969, the Harrier GR.1 officially entered service with the RAF when the Harrier Conversion Unit at RAF Wittering received its first aircraft. The United States Marine Corps (USMC) also chose to procure