A Flybe flight plummeted 500ft in 18 seconds after an incorrect autopilot setting caused it to aim for the ground, a probe has found.
Forty-four passengers and four crew were on board the flight from Belfast City Airport to Glasgow Airport when the incident occurred shortly after take-off on January 11.
A report by the Air Accidents Investigation Branch (AAIB) stated that the autopilot was engaged when the Bombardier Dash 8 Q400 turboprop plane reached an altitude of 1,350 feet.
The aircraft continued to climb to 1,500ft (about one-third of a mile up) but it “pitched nose-down and then descended rapidly” because autopilot was mistakenly set with a target altitude of zero.
Cockpit alarms alerted the captain and first officer to what was happening. They later reported they had “become visual with the ground”.
The captain disconnected autopilot and recovered the aircraft, having dropped to 928ft.
The maximum rate of descent of 4,300 feet per minute during the event suggests the aircraft may have hit the ground just a few seconds later if the crew had not intervened.
They continued the flight to Glasgow and landed without incident.
The AAIB concluded the crew’s selection of a particular autopilot mode before take off led to the zero altitude target.
Flybe has taken several safety measures in response to the incident, including revisions to simulator training and amendments to pilots’ pre-take off checklists.
A spokeswoman for the airline said: “Flybe maintains a rigorous approach to ensuring the very highest flying standards are maintained.
“As reported by the AAIB, Flybe implemented remedial actions quickly in response to the incident and our training and procedures have been amended to minimise the risk of a reoccurrence.
“Flybe operates over 158,000 flights a year and the safety of our passengers and crew remains our number one priority.”
It is not the first near-catastrophe on a Northern Irish flight in the last few years.
In July 2017, there was a bungled take-off of a Boeing 737 with 185 people (including crew) on board as it left Belfast International Airport for Corfu. On that occasion, the AAIB said “the aircraft tyres struck a runway approach light”, standing just 13 inches high, when it was already a full 95ft beyond the end of the runway.
It said the only credible reason for this was an error in entering data in the flight computer.