Small Transport
Flight Crew Multiengine; Flight Crew Commercial
Flight Crew Last 90 Days 120; Flight Crew Total 2200; Flight Crew Type 1800
Distraction; Communication Breakdown; Situational Awareness
Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors; Procedure
My aircraft is involved in a project [under a government] contract. We drop small packets of vaccine out of the aircraft for wildlife vaccination. Flights are flown in a grid over a large area. Before beginning the dispersal near Del Rio; flights were coordinated with the Air Force; Border Patrol; any controlling towers; and multiple other agencies. All flights are conducted at 500 AGL to facilitate a machine operator to cut off the machine whenever we pass over any buildings or populated areas.On the day of the incident; flights began at sunrise; and my drop area was right along the Mexico/US border. After an hour of flight; I was north bound and saw an aircraft about 3-5 miles off my nose. I continued to watch the aircraft; and pointed out the aircraft to the machine operator in the front seat beside me. The aircraft was at least 500 feet above me; and seemed to be on a constant heading. I tried raising him on Del Rio's frequency; since I had heard an aircraft depart just prior to seeing this aircraft. I was not able to raise him. Seeing no conflict; and believing (due to their trajectory) there would be more conflict if I turned north (right); and I could not turn south into Mexico; I continued the line and passed underneath the aircraft well below his altitude. I did not see any conflict and was not worried in the least.Upon reaching the ground; I found out that the aircraft was a Civil Air Patrol (CAP) aircraft that had a border patrol agent on board. The agent had not been informed of our activity in the area; even though his supervisors had been notified. The pilots of the CAP aircraft were very unhappy about the situation and asked for my name. They had not seen my aircraft until we were underneath them.
A pilot reported an airborne conflict during a government contracted animal vaccine dropping flight that required grid pattern operations. Notification of the operation had not been disseminated to an associated agency.