SUTTER COUNTY -- A day after two pilots were killed when their crop dusters collided in Sutter County, investigators with the National Transportation Safety Board are looking into what may have caused the mid-air collision.
Meanwhile, aviation experts are also weighing in on just how difficult rice planting from the air can be.
Friends of 62-year-old Brian Van Dyke and 58-year-old Burton Haughley said they don’t know how the two experienced pilots collided while planting rice seed Wednesday afternoon.
"You think there’s so much sky out there and how is it possible that two people run into each other? You just can’t believe that it can," said friend Tom Beilby.
NTSB agents are now in the fact-gathering phase of their investigation.
"All aspects will be looked at: The maintenance records on the aircraft, the pilot training records, any possible incidents that the companies or the pilots may have had in the past," said Scott Miller, a professor of aeronautics at Sacramento City College.
Miller said flying crop dusters is some of the most physically demanding flying there is.
"It’s typically long hours, sun up to sun down during this time of year, and the fact that you're down low where it's hot and where it's turbulent. And then those pitch-up maneuvers required at the end of each pass to get lined up for the next pass is stressful, you know," he told FOX40. "The human body, like anything else, over time gets used to it. I have a lot of respect for these individuals doing this type of aerial application flying."
Miller said the Grumman Ag Cats the two were flying are designed to operate low and slow and close to the ground. Sometimes pilots can fly as low as only 5 feet above the fields they’re planting rice in.
While he does not know all the specifics, Miller believes both planes were turning around when the collision happened.
"When you get to the end of the field you need to make a reversal maneuver, which involves a pretty high pitch-up and then a turn around back down," Miller explained. "And it appears, just by looking at the location of the fields that they were working, that possibly there was a mutual pull-up and just terrible, terrible, tragic bad luck."