The U.S. Transportation Department's drone registration task force gathered today in Washington, D.C., to start work on recommending requirements for marking and tracing ownership of unmanned aircraft systems (UAS). A key question for the 26 task force members was framed by FAA Administrator Michael Huerta: What products should we exclude from registration based on weight, speed, altitude and flying time? That begs the question of what drones pose hazards to helicopters and other aircraft based on their weight, speed and other characteristics. That matter is under study in various quarters, but bird strikes may offer a starting point for research. The 2011 crash of a U.S. Marine Corps/Bell Helicopter AH-1W at Camp Pendleton, California, is a case point, according to Mike Hirschberg, executive of the vertical-flight technical society AHS International. Both pilots on the Cobra were killed in the crash that was attributed to a 3-lb red tail hawk's collision with a pitch change link, which led to separation of the main rotor. Drones flying at higher airspeeds and those made of metal or other hard synthetic parts could cause similar damage to a helicopter rotor system, windshield or engine, Hirschberg posited, particularly since helicopters and small drones occupy the same low-level airspace.