The pilot operating a helicopter scanner which hit a powerline near Balmedie last year was “not aware” of height loss, an investigation has found.
The Air Accidents Investigation Branch (AAIB) has today published its report into the incident which resulted in a power loss for more than 1,600 homes.
On September 17, the AS0-350 helicopter was conducting a survey operation from a field near Auchmacoy in Aberdeenshire.
It is understood the work was being carried out on behalf of Aberdeen Minerals Limited (AML) to scan for potential commercial deposits of base metals in the area.
The AAIB report states: “The incident occurred during the first scheduled survey using the system in the UK, although the system has been operated globally for 17 years and has covered 1.3 million km of survey lines.”
Pilot ‘unaware’ of collision
At about 10.45am, the 73-year-old pilot maneuvered to a new survey track, reducing speed in the process, which resulted in a loss of height.
During this time, the underslung antenna, the sensor attached to the helicopter and carried 164ft below the aircraft, striking an electricity pylon.
Nobody was injured during the incident.
A risk assessment had been completed prior to the survey with measures put in place so the risk register could be recorded as low.
The report states: “The underslung antenna struck an electricity pylon as the helicopter manoeuvred between survey lines. The pilot had reduced speed to minimise the turn radius to keep the antenna clear of buildings.
“However, it is likely as the speed reduced and the power demand consequently increased the pilot did not accurately control the height of the aircraft and allowed the descent.
“The antenna was therefore below its intended survey height and struck a pylon that was 26ft tall, severing the power cables. Unaware of the collision the pilot continued his planned survey.”
Properties lost power
The severed power cables resulted in the loss of power for a total of 1,682 properties in the Balmedie area.
At the time, SSE confirmed that 58 postcodes were affected and had engineers on site to resolve the issue as quickly as possible.
Most homes had power reinstated by 3pm that afternoon.
In summary, the AAIB report states: “The pilot was not aware of a height loss during a low speed manoeuvre between planned lines of an aerial survey.
“As a result of the height loss, the aircraft’s underslung load was below its intended height and struck an electricity pylon that had not been identified as a relevant obstacle on the route.”
Conversation