Aviation Safety Letter 2/2003

The Danger of Power Lines: Balloon — Aerostar RX-7

Balloon hitting power lines

The pilot checked the weather three times before departure. The weather forecast for the flight was: winds from 280° true at 10 kts; visibility greater than 6 SM; a broken cloud layer at 3 000 ft AGL; and, temporarily [from 17:00 to 20:00 eastern daylight time (EDT)], visibility 6 SM in light rain showers. The winds, as measured at takeoff, were from the north-northwest at approximately 3 kts. During most of the flight, the weather was favourable, however towards the end of the flight, the pilot saw that the sky to the east of his intended flight path was getting dark, so, he decided to land as quickly as possible. He reported that the winds on landing were approximately 4-6 kts (7 mph) and had been relatively constant throughout the flight.

The initial landing site was at a distance of about 600 ft upwind of a road and some power lines. The landing was a little bumpy but the basket did not tip over. The pilot, who had over 500 hours of experience, then established the balloon in equilibrium and the ground crew walked the balloon closer to the road for ease of recovery. Upwind of the road and approximately 240 ft upwind of power lines, a second landing was made and the deflation process initiated. Suddenly a gust of wind picked up the balloon with the pilot and two passengers in the gondola and one ground crew hanging on the outside of the basket. The ground crew let go at a height of approximately 15 ft, and fell to the ground. The balloon drifted with the wind, and became entangled in the power lines. An electrical arc occurred and the gondola caught fire. There were injuries and one casualty.

The balloon flight manual suggests maintaining at least 100 ft of horizontal separation from power lines for each mile-per-hour wind at the landing site. The location of the initial landing site was close to this requirement; however, when the balloon was walked closer to the power lines, the separation was lost. As winds associated with towering cumulus can be unpredictable, better use of the recovery truck might have averted disaster.

Source: TSB file A01O0200.

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