What aircraft was involved and where did it happen?

The accident on 2003-07-21 involved a SA341G, registration G-BAGL, at Street Farm, Street, Essex, GB.

What was the probable cause of the accident?

The aircraft struck power cables that were difficult to see due to their green colour, the obscuring foliage of nearby trees, and the visual background of farm buildings.

Gazelle 1 strikes power cables during departure in Essex

A private flight involving an SA341G Gazelle 1 struck overhead power cables while climbing away from a landing site in Essex, resulting in significant damage to the aircraft.

What happened

On 21 July 2003, an SA341G Gazelle 1, registration G-BAGL, was departing from a private landing site at Street Farm, Essex, destined for Leicestershire. The flight was a private operation conducted in favorable weather conditions with a south-south-west wind of 12 to 15 knots.

As the pilot transitioned from a low hover into forward flight on a westerly heading, the aircraft's front canopy struck three power cables. These cables were suspended at a height of approximately 30 feet. The impact caused the aircraft to pitch forward. In an attempt to recover, the pilot applied aft cyclic and increased collective pitch. During this maneuver, the main rotor blades struck the lateral fins and the tail cone fairing, which severed a hydraulic pipe connected to the fenestron controls. The impact also caused the power cables to snap.

Despite the damage, the pilot maintained control of the aircraft, flying south for roughly 100 metres to clear nearby farm buildings before turning left. The aircraft was successfully landed in a field north of the original site without further incident. There were no injuries to the pilot.

The investigation

The investigation established that the landing site was a field bordered by trees, hedges, and fencing. To the west of the field, power cables ran north-south near farm buildings. The investigation examined the visibility of these obstacles and the sequence of the rotor blade impact. It was noted that the poles supporting the cables were obscured by leafy trees, and the cables themselves were green, making them difficult to detect. The investigation also looked at the pilot's flight path, which was intended to avoid both the farm buildings and the airspace of Stansted Airport.

Findings

The primary cause of the incident was the impact with power cables during the transition to forward flight.
The cables were difficult to identify because they were green in colour and set against the background of farm buildings.
The horizontal arrangement of the cables at the same height, rather than staggered, likely made them harder to perceive once airborne.
The poles supporting the cables were hidden by trees in full leaf.
The pilot acknowledged that a more thorough assessment of obstacles during the pre-flight walkround could have prevented the occurrence.