Obstacle Clearance and Delivery.

Wire strikes involving general aviation fixed-and rotary-wing aircraft are on the rise again in various parts of the world. In addition to including transmission line locations, system designers are also adding a special power line alert. Onboard obstacle warning systems exist and others are under development to help pilots steer clear, but these can be expensive — too expensive for many operators. There are a number of active and passive obstacle warning systems on the market or moving toward certification. A sampling includes the EADS/Dornier Hellas, a laser and radar system, which can detect power lines with diameters as small as a quarter-inch at a distance of 3,281 feet INSET: Alerts, Affordably.