ALBUQUERQUE, N.M. — Jun 11, 2015, 2:26 PM ET

 The single-engine plane came in low as the seasoned pilot maneuvered to give his gunner a clear shot at a coyote on the ground below. They were on a mission to hunt down predators that had been killing livestock in northeastern New Mexico.

A spotter less than a mile away had his binoculars trained on the coyote. He heard two or three gunshots as the plane passed over its target and through his field of view. Moments later, he heard a crash and looked up to see the plane planted in the ground.

Pilot Kelly Hobbs and his gunner, Shannon “Bubba” Tunnell, were killed. A preliminary report by the National Transportation Safety Board released late Wednesday says the impact pushed the engine into the cockpit.

No strangers to the risks of aerial gunning missions, the men left the Raton airport just after dawn on June 5. After passing over the edge of a mesa and spotting the coyote, the pilot began to descend. At one point, the plane was flying just 42 feet above the prairie, according to GPS data.

After Tunnell took his shots, Hobbs began to climb to the left. The last reading showed the plane was nearly 100 feet off the ground and its speed had dropped to 62 mph through the turn.

Ranchers across New Mexico are mourning the two men, who were working for the U.S. Department of Agriculture’s Wildlife Services branch at the time of the crash. Ranchers say they would often turn to Hobbs and Tunnell for help in protecting their cattle and sheep from predators.

“It hit me pretty hard when I heard about it. It was just like a punch in the stomach,” said Candy Ezzell, a state lawmaker who worked with Tunnell just weeks earlier to address coyote problems on her ranch in southern New Mexico.

Funeral services for both men were planned Friday.

Their deaths bring to 12 the number of public employees killed during Wildlife Services aerial gunning operations in the U.S. since 1979. Many of the aerial missions happen in the West, where sheep and cattle ranchers regularly report problems with predators.

Hundreds of thousands of hours have been logged by Wildlife Services pilots over the decades. Agency officials stand behind their safety record, but environmentalists argue that the costs are too great and the federal government should end aerial gunning. They pointed to the fatalities along with more than 100 crashes and dozens of injuries.

“In no uncertain terms, putting agents into the air so they can gun wildlife from low-flying aircraft is so inherently dangerous and reckless,” said Wendy Keefover of The Humane Society of the United States.

A review of accident investigations shows pilots have flown into power lines, trees and land formations, Keefover said. Some also have flown back into their air turbulence and in several instances, gunners have shot their own aircraft or bullet casings have become lodged in mechanical workings.

The call to halt the practice stretches back to the last deadly crash in 2007 in Utah. At the time, Wildlife Services responded by launching a safety review.

As for the potential of another review, agency spokeswoman Lyndsay Cole said the focus now is on helping investigators determine what caused the latest crash in New Mexico.

The preliminary report states the weather was calm and there was no apparent evidence of any mechanical malfunctions or failures that would have caused engine problems.

 Flying low and at relatively slow speed is risky, but Ezzell and other ranchers say aerial gunning operations are invaluable since controlling predators across such large swaths of land can be difficult. Trapping and coyote-calling contests have also come under fire, leaving ranchers with fewer options.

“With folks in the city wanting to end trapping and calling, it has become a real issue for the ag community and has affected the state’s ability to manage wildlife,” said David Sanchez of the Northern New Mexico Stockmen’s Association.

Aerial operations were used by Wildlife Services last year to kill more than 35,000 animals in two dozen states. That included more than 21,000 coyotes.

The agency targets animals that prey on livestock and other wildlife as well as nonnative species that damage crops or cause problems at airports. A total of 2.7 million animals, the majority of them birds, were killed last year.