"We were probably going about 70 miles per hour, it was pouring down rain, and all of a sudden I thought we'd been hit by another vehicle," said Sparks.
"This huge ball of fire was right up in front of the truck, and all the lights went out and the truck went in neutral. I figured out right then we'd been hit by lightning."
The immediate sensation, Sparks said, was of unbelievably bright light everywhere inside the truck.
"It was so bright it almost blinded me," he said. "Ruby was in the bed in the back of the cab, and the force jarred her forward to hit the safety netting. And the sound - if you've ever heard a tire on one of those big trucks blow out, imagine holding your ear right next to it when it blows. That's what it sounded like inside that cab."
Sparks said the bolt knocked out the power steering on the truck, leaving him to wrestle the big rig to the side of the road.
"It was pretty touchy there for a minute, because the lightning knocked out the lights, and I couldn't see where to pull over," he said. "I used the lights from cars behind me to find the shoulder, and finally got it pulled off enough to be out of the way."
Once out of the way of oncoming traffic, Sparks said he had to figure out how much damage the truck suffered.
"We didn't know at that point whether or not we were on fire, or what might be happening," he said. "So here we are, in this driving rain, trying to figure out how bad we were damaged. It wasn't all that bad, and we weren't in danger of anything unless the lightning decided to hit us again."
The diesel engine on the truck didn't stop running, but without lights on a dark night, continuing on was not an option. The Sparkses waited in their rig for almost two hours for a tow truck, and not long afterward they were motoring on to Dallas in another rig.
"We lost a day of our vacation because of the delay, but that's better than what we could have lost," said Sparks, who was ordained as a minister Saturday. "I've heard of lightning striking trucks before, but I never expected to see it up close and personal like that. You get the feeling of awesome power, that's for sure."
Sparks said neither he nor his wife lost personal control during the hectic few minutes after the strike.
"You don't have time to be scared," he said. "Ruby yelled something like 'Oh Lord' when it knocked her around, but all I could think of was I couldn't see how to park this big thing, and it didn't want to turn when I turned the steering wheel.
"There was a part of my brain that figured out what happened and all that, but you don't really wonder about it until you get stopped and think back."
According to the National Severe Storms Laboratory, a research arm of the National Oceanic and Atmospheric Association, the parent group of the National Weather Service, no place is absolutely safe from lightning, which it estimates strikes somewhere in the United States nearly every day of the year.
However, according to NOAA, "In general, fully enclosed metal vehicles such as cars, trucks, buses, vans, fully enclosed farm vehicles, etc. with the windows rolled up provide good shelter from lightning. Avoid contact with metal or conducting surfaces outside or inside the vehicle."
Sparks said he begs to differ.
"That stuff strikes wherever it wants to, and that old myth about being on rubber tires keeping you safe is just that, a myth," he said. "I believe those rubber tires might have kept it from being any worse than it was, but it didn't keep us from being hit."
The Sparkses were able to take their vacation, a day late, but tonight they'll be back on the road with a new company truck.
"It's what we do," he said. "Besides, what are the odds of us getting struck again?"