Airplanes Have Been Flown By Remote Control Since 1917

In 1917, Archibald Low as head of the RFC [Britain's Royal Flying Corps] Experimental Works, was the first person to use radio control successfully on an aircraft.
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There were also [during the 1930s] remotely controlled cutters and experimental remotely controlled planes in the Red Army. In the 1930s Britain developed the radio controlled Queen Bee, a remotely controlled unmanned Tiger Moth aircraft for a fleet's gunnery firing practice. The Queen Bee was superseded by the similarly named Queen Wasp, a later, purpose built, target aircraft of higher performance.

On the 31st July 1944 a U.S.N. special air unit, codenamed Project Anvil, moved to Fersfield from Dunkeswell in Devon. The mission was to involve the use of explosive-laden PB4Y-1 Liberator bombers under radio control. The crew of two, Lt Joe Kennedy (pilot), and Lt. Wilford John Willy (radio control technician/co-pilot), were to take off with 21,150 lbs of Torpex in 347 boxes and establish radio control of the Liberator by a Ventura mother-ship. Once full control was established and tested, at a pre-determined point the crew would parachute from the aircraft through the nose wheel bay emergency exit and the bomber would continue the rest of its mission under radio control, finally crashing onto the target.

NORAD (the North American Air Defense Command) had at its disposal a number of U.S. Air Force General Dynamics F-106 Delta Dart fighter aircraft configured to be remotely flown into combat as early as 1959 under the auspices of a program know as SAGE. These aircraft could be started, taxied, taken off, flown into combat, fight, and return to a landing entirely by remote control, with the only human intervention needed being to fuel and re-arm them.

The Semi-Automatic Ground Environment (SAGE) was an automated control system for tracking and intercepting enemy bomber aircraft used by NORAD from the late 1950s into the 1980s. In later versions, the system could automatically direct aircraft to an interception by sending instructions directly to the aircraft's autopilot.
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In normal operation, communications between the SAGE centers and the interceptor aircraft was relayed via radio equipment at the radar sites, which were more widely spread out than the SAGE centers themselves. A properly equipped aircraft, like the F-106 Delta Dart, could feed the SAGE directions into the autopilot and fly "hands off" to the interception.

In 1984 NASA Dryden Flight Research Center and the Federal Aviation Administration (FAA) teamed-up in a unique flight experiment called the Controlled Impact Demonstration (CID), to test the impact of a Boeing 720 aircraft using standard fuel with an additive designed to suppress fire.
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On the morning of December 1, 1984, a remotely controlled Boeing 720 transport took off from Edwards Air Force Base (Edwards, California), made a left-hand departure and climbed to an altitude of 2300 feet. It then began a descent-to-landing to a specially prepared runway on the east side of Rogers Dry Lake. Final approach was along the roughly 3.8-degree glide slope.

"Most modern aircraft have some form of autopilot that could be re-programmed to ignore commands from a hijacker and instead take direction from the ground . . . ."