A Flybe plane on a flight from Ronaldsway with 61 passengers on board had a near-miss with Runcorn Bridge as it came to land at Liverpool John Lennon Airport.
Details of the incident are outlined in a report by the Air Accident Investigation Branch.
The Dash 8 plane was coming into land at 9.07am on June 1 this year when it flew below the recommended glide slope, resulting in an cockpit alert sounding.
However, the flight crew took appropriate action to correct the danger and made a safe landing.
Given the good weather and absence of other air traffic, the co-pilot had asked the commander if he could to convert to a visual approach. The co-pilot disengaged the autopilot and turned the aircraft, tracking Runcorn Bridge while descending.
He was concerned he may fly above the ideal glide path if he turned towards the runway too early, so had maintained his descent - but in doing so, the aircraft descended below the recommended ‘profile’.
The aircraft had been descending at a rate of about 2,000ft per minute and a ‘Caution Obstacle’ alert was sounded at a radio height of 894ft as it approached the runway.
Runcorn Bridge is 285ft over the riverbed and crosses the River Mersey.
The Enhanced Ground Proximity Warning System (EGPWS) uses internal terrain, obstacle and airport databases to predict a potential conflict between a flight path and terrain or obstacle.
‘The obstacle concerned in this case was not positively identified, but was possibly the Runcorn Bridge,’ the report says.
The flight commander said he himself had become distracted from monitoring the vertical profile. He prompted the co-pilot to turn right towards the runway at about the same time as the EGPWS’s alert sounded.
The flight crew adjusted the aircraft’s flight path and confirmed it was safe and appropriate to continue the approach.
Flybe said safety of its passengers and crew is its number one priority.
A spokesman said: ‘The event highlighted in the AAIB report was thoroughly investigated by our own investigators and through correspondence with the AAIB.
‘Both parties concluded that at no time was the safety of the flight compromised. However, in light of the event, and despite the AAIB making no recommendations, Flybe has taken a number of actions to further improve safety.’
Meanwhile, the Civil Aviation Authority has revealed there were 45 incidents of laser pens being shone at aircraft at Liverpool Airport last year.