A Mi-24 ‘Hind’ attack helicopter was forced to take avoiding action after a drone was spotted during a military exercise in Russia.

In social media was released the short video clip shows a drone flying above a military helicopter during a practiced assault river crossing and tactical landing exercise. The terrifying footage shows a close call between the drone and the Mi-24 helicopter recorded from the drone’s onboard camera.

A collision between a drone and aircraft could have dramatic consequences. With the increasing number of drones in service, and the increasing number of drone pilots, many of them ignoring the regulation, they’re a real threat to the safety of civil and military aviation.

Even a small drone crashing into an airplane can do major damage, that previously confirmed by Kevin Poormon, a University of Dayton engineer who.

Kevin has performed numerous bird strike tests on airplanes, mimicked a mid-air collision between a 2.1-pound DJI Phantom 2 quadcopter and a Mooney M20 airplane. The drone bore into the plane much farther than a similarly weighted gel “bird” and damaged the plane’s main spar, which carries the weight of the wing. Debris spewed from the aircraft.

A study by a Federal Aviation Administration research center made similar findings, saying drones’ more rigid materials allow them to cause greater damage than birds.