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Law-enforcement agencies across the country have adopted aerial drones to map crime scenes, monitor large events and aid search-and-rescue operations. But the high-flying devices have also triggered backlash over fears they will be used to spy on law-abiding citizens.

The New York Police Department on Tuesday unveiled plans to deploy 14 of the unmanned fliers and to train 29 officers to operate them, opening an intense debate about whether an agency previously criticized for illegally surveilling citizens should possess such powerful technology.

Senior police officials said the drones would be used for monitoring giant crowds, investigating hazardous waste spills, handling hostage situations and reaching remote areas in crime scenes, among other tasks. They will not be used for routine police patrols, unlawful surveillance or to enforce traffic laws, the officials said. Nor will they be equipped with weapons.

“Drone technology will give our cops and their incident commanders an opportunity to see what they’re getting into before they go into harm’s way,” Chief of Department Terence A. Monahan said. “For this reason alone, it would be negligent for us not to use this technology.”