The plane had taken off from Belfast City Airport and climbed to 1,350feet before the accident happened.
The Flybe flight out of Belfast fell more than 500 feet in 18 seconds. Early autopilots were only able to maintain a constant heading and altitude, but modern autopilots are capable of controlling every part of the flight envelope from just after take-off to landing.
At one point, the crew in the cockpit was looking straight at the ground.
In the United Kingdom the pilot of a Flybe airline flight made a mistake with the settings of the autopilot, and this has led to a sharp decrease of the aircraft, noted in a released on 8 November the official investigation report of the incident, which happened on January 11.
They continued the flight to Glasgow and landed without incident.
The setting was disconnected by the pilot when the aircraft dropped to 928ft. At its fastest, the plane descended at a rate of 4,300 feet per minute.
A last-minute change in the plane's payload left the crew with less time to carry out preflight checks and they missed the problem with the autopilot setting, the report said.
However, they soon realized that something went dangerously wrong, when the plane, after reaching the altitude of about 457 meters, suddenly "pitched nose-down" and rushed to the ground, activating both "don't sink" and "pull up" warnings, a report on the incident issued by the Air Accident Investigations Branch (AAIB) on November 8, says.
The AAIB concluded that the incident was down to the crew's selection of a particular autopilot mode before take-off.
Flybe, an independent regional airline based in England, said it "implemented remedial actions quickly in response to the incident" and changed procdures and training to lessen the risk of a similar incident.
Airline Flybe after the incident has revised the training on the simulators and added to the checklist.
"Flybe operates over 158,000 flights a year and the safety of our passengers and crew remains our number one priority".