The Human Grounding Rod
The weather forecast was typical of a warm, North Carolina spring afternoon — visibility was great with 10 miles and a 30 percent chance of isolated thunderstorms. We had based our mission operations out of a local airport. As lead aircraft in a flight of three Black Hawks, we were completing our last leg of what was considered a routine infiltration/exfiltration mission.
We were 15 miles from the base operations airport and closing quickly. The unit flight operations had already radioed a weather update reporting a line of thunderstorms in the area, so we knew we needed to hurry. In the distance, lightning began flashing around a storm we were attempting to beat back to the airport.
We’d only been on the ground a few minutes and had begun to shut down when torrents of rain started to fall. All crew chiefs were directed to get back in the aircraft. Lightning was striking close enough that no one wanted to be outside or make the risky 100-yard dash to the fixed base operations building. Instead, everyone held fast at their crew duty stations inside the aircraft.
After a period of time, the rain began letting up and everyone either got out or shifted around within the aircraft, trying to stay dry while getting get a breath of fresh air. Most moved to the cargo area inside the aircraft because the rain water was still flowing over the tarmac.
The wind continued to blow a light rain over the aircraft. The left cargo door remained open, but it somewhat sheltered us from the elements. That’s where I decided to stand. I leaned back against the two center forward/aft facing seatback support posts to wait out the rain.
We had pulled out the laptop to close the mission and began to informally discuss the after-action details when another wave of wind and rain resumed with lightning trailing three to four miles away. In what seemed like 15-20 seconds, the lightning moved to within one-half a mile. I moved toward the inside the aircraft, but wasn’t quite fast enough.
A bolt of lightning lit up the immediate area with a brilliant flash accompanied by the sound of electricity moving over the outside skin of the aircraft. The hair on my arms and neck literally stood on end. There was a sudden loud snap (like that of arcing electricity) and a sting in the middle of my back. The jolt of electricity took my breath away, moving down my back and legs to the ground and leaving a small, red welt on my back. My legs and feet felt numb and tingly, and I was now six feet from the aircraft, bent over.
I know the aircraft has grounding cables on the inside of each main landing gear, but bigger is better (as far as grounding goes). The “path of least resistance” comes to mind. Lightning had moved over the skin of the aircraft and down the metal cargo area seatback support posts. The strike left two one-eighth-inch scorch marks one-quarter an inch apart on the seatback support post canvas covering. I’m not sure what the right answer was to prevent this incident, but one thing is for sure: It wasn’t standing outside the aircraft acting as an additional grounding rod!Did You Know?
In the United States, there are an estimated 25 million lightning flashes each year. During the past 30 years, lightning killed an average of 62 people per year. Lightning can strike not only people on the ground; it can also strike the skin of an aircraft and its electronic components. Lightning generally occurs within 5,000 feet of the freezing level, in light precipitation or light to negligible turbulence. Lightning “crawlers” can travel more than 35 miles along the clouds and have been observed out to 75 miles on radar.