Hybrid Air Vehicles Ltd can confirm a mooring line attached to the Airlander did contact a power line outside the airfield. No damage was caused to the aircraft and this did not contribute to the heavy landing.
HAV state that the heavy landing was not caused by contact with the power line(s).
Therefore, in the absence of obvious adverse weather conditions, the accident must have been caused by one or more of the following:
1. Control system inadequate design.
2. Control system malfunction.
3. Buoyancy control malfunction.
4. Pilot error of technique, judgement or skill.
5. Other cause?