A new chapter in civil aviation history began yesterday when the FAA issued the first airworthiness certificate for a commercial unmanned aerial vehicle (UAV), the General Atomics Altair. The UAV, a high-altitude version of the U.S. military's Predator B, is designed to perform scientific and commercial research missions. The Altair has an 86-foot wingspan, a 52,000-foot ceiling and an endurance of 30 hours. The Altair's certification is in the "experimental" category and limits flights to research and development, crew training or market survey. The agency has also specified a number of safety conditions for the Altair's operation, including weather, altitude and geographic restrictions, as well as a requirement for a pilot and observer, both of whom may be either on the ground or in an accompanying chase airplane. Initially, the UAV will be limited to VMC only at or below 13,000 feet and must stay in a designated block of airspace over the Mojave Desert/Edwards AFB.