Small Aircraft
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Flight Instructor
Flight Crew Last 90 Days 25; Flight Crew Total 1000; Flight Crew Type 250
Situational Awareness; Workload; Distraction
Airspace Violation All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification
Human Factors; Procedure; Environment - Non Weather Related
I was acting as a CFI on a training flight with a student returning to our home base PAO when we flew past a drone in the traffic pattern.  My student was flying.  We were entering the left downwind for runway 31 at PAO from a standard 45 degree entry when I spotted an unmanned drone 2-3 feet in size at our altitude; which was the standard left pattern altitude for 31 at PAO.  We passed within approximately 100 feet of the drone and took no evasive action.  It appeared to be hovering with no discernible motion.  My student indicated that he did not see it.  There were no prior traffic advisories from PAO tower or PAO ATIS regarding the drone or drone activity in the area.  I reported the drone to PAO tower and tower made a broadcast to all aircraft of our drone report.By the time I saw the drone and recognized it as such; we had nearly flown past it.  Such a small vehicle is difficult to spot until very close in.  I usually focus on traffic scanning at distances that are further away.  I had recently attended a meeting at PAO for CFIs where reports of nearby drone activity was mentioned and I think this helped me recognize it as a drone more quickly.  Some pilot awareness of local drone activity may help facilitate close-in visual scanning and faster recognition of these small vehicles.    Legislation requiring firmware in these commercially manufactured drones that prevents operation outside of the FAA limits would improve safety.  The distribution of information to drone purchasers regarding local flight restrictions; airport locations; etc. may also help prevent this incident from occurring. To put this event into some context; bird activity also creates hazards at PAO and I have had several near collisions with birds there and elsewhere flying over many years.  However; birds usually dive out of the way while the drone did not.  This drone also likely weighed significantly more than a bird.
An instructor with his flying student was entering a 45 degree left downwind for PAO Runway 31 at 1;000 FT when he detected a UAV about 2-3 FT wide; approximately 100 FT beneath his aircraft.