The operators in the study were divided into three groups of people who work hand in hand: Pilots who remotely fly the drones, sensor operators who control the cameras that bring the battlefield into view and mission intelligence coordinators who communicate with troops on the ground. There was also a difference among the drones in the study: Predators and Reapers are armed, and Global Hawks are not.

In one surprising finding that challenged some of the survey’s initial suppositions, the authors found limited stress related to a unique aspect of the operators’ jobs: watching hours of close-up video of people killed in drone strikes. After a strike, operators assess the damage, and unlike fighter pilots who fly thousands of feet above their targets, drone operators can see in vivid detail what they have destroyed.

“The going-in assumption was that we were placing these guys under a great amount of stress because of all this video feed,” said Col. Kent McDonald, the chief of neuropsychiatry at the school of aerospace medicine and one of the study’s two authors.

In one-on-one interviews with 85 operators, the authors found that many felt a sense of accomplishment in protecting troops on the ground. Soldiers and Marines who get pinned down in insurgent fire in Afghanistan often call in airstrikes to get themselves out of trouble, and a drone that comes buzzing overhead is a highly welcome sound. Guided by communications with American troops on the ground, drone operators are then able to aim their missiles directly at insurgents. “These guys are up above firing at the enemy,” Colonel McDonald said. “They love that, they feel like they’re protecting our people. They build this virtual relationship with the guys on the ground.”

Wayne Chappelle, the chief of aerospace psychology at the Air Force school and the study’s other author, said he learned in the interviews that ground troops sometimes sought out the operators by e-mail after a successful strike. “They would want to just say, ‘Hey, thanks, man,’ ” Dr. Chappelle said.