The draft FAA rule that will provide a regulatory framework for operating small unmanned aircraft systems (UAS) of about 55 pounds or less in unrestricted airspace will likely limit those aircraft to flying 400 feet agl or below, within visual line of sight of an observer on the ground and during day VMC. The “sense-and-avoid” aspect of keeping safe separation from other aircraft will be provided by a ground observer, said Ted Wierzbanowski, chairman of ASTM International Committee F38, which is developing UAS standards under an agreement with the FAA.

Wierzbanowski, who spoke on August 7 at the Unmanned Systems North America conference in Las Vegas, said he has not seen the proposed rule that the FAA is promulgating. But the agency’s notice of proposed rulemaking (NPRM) is expected to closely follow the 2009 recommendations of a small UAS rulemaking committee that Wierzbanowski co-chaired.

The expected release of the NPRM by year-end is running about a year later than planned, a delay that has put off the issuance of a final rule until 2014.