One of the most risky helicopter operations in the business is "live-line" work, where a crew repairs electricity supply lines and the pylons between which they are slung. In the past few years, helicopter crews have died or been injured while hovering so close to a line that a gust of wind has caused the skid to snag on the wire and throw the helicopter into a spiralling fall with damaged main and tailrotors.

It sounds dangerous enough to be outlawed. But according to the UK Civil Aviation Authority, by which the activity is regulated, analysis and adherence to planned methods and procedures can reduce risk to acceptable levels. UK electrical distribution network provider National Grid has a safety record that proves the point. National Grid's chief pilot, Capt Peter Gilbert, says the company has a strong safety ethos. Its line inspection and line-repair work has been subjected to an independent risk analysis by Aston University in the UK. The result has been a set of method statements that are regularly reviewed.

The team for live-line repair work consists of two pilots in a twin-engined helicopter, two maintenance engineers in the underslung basket, and two observers on the ground - one ahead monitoring lateral risk and one at the side monitoring fore and aft, but both well clear. All team members have voice communications with back-ups, and the insulated load line holding the basket is at least 30m (98ft) long. In the event of a problem, the basic drill is either to set the basket down, then drop the line and fly clear, or to set it down and land alongside it. The team may spend around 70h a year on such work, which is not enough to keep it in practice, so live refresher training is carried out as required.

Source: Flight International