Narrative:

After completing our search and rescue mission, we turned north towards opf. After approximately 20 mins in cruise, the captain looked to his left and noticed our airplane's shadow, along with the shadow of another aircraft in extremely close proximity to our own. The captain then asked me to look at our 5-6 O'clock position and determine whether or not there was an aircraft in close proximity to us. While looking back towards our tail section, I saw the right wing of another airplane which appeared to be traveling directly behind us, at the same altitude, and no more than 50 ft away. The captain seemed concerned about this unidented aircraft. In order to try to make this aircraft move away, the captain initiated a series of small rolls in opposite direction (rocking the wings). After this action, the aircraft moved to our 5:30 position, where I observed that the aircraft following us was a twin turbojet pwred airplane, presumably a cessna citation operated by united states customs. I informed the captain of my observation, and he instructed me to contact our ground controller. I informed the ground controller of our situation, and asked him to relay our situation to the united states customs office. During the intercept, the airplane (assumed now to be customs), remained at our 5:30 position in dangerously close proximity. After apparently reading our tail number, the aircraft disappeared. The airplane was in close proximity for approximately 2 mins that we know of. As a precautionary measure, we asked our ground controller to inform opf tower that we would be landing with an inoperative transponder. When we approached opf airspace, the ATC controller confirmed that our transponder was inoperative. After landing, our ground controller confirmed that the aircraft which intercepted us was a united states customs aircraft. The airplane which intercepted us did not attempt air-to-air contact on 122.75 MHZ, nor did they give hand signals or aircraft motion signals as prescribed in aim paragraph 5-90, 5-91, or table 5-93 of the same. In addition, they did not attempt any sort of communication. Callback conversation with reporter revealed the following information: the reporter flies the cessna skymaster for a volunteer organization that helps in the search and rescue of cuban boat people. His organization calls customs before departing for a search mission and the pilots are on a cordial basis with customs. When they find a boat or raft, they drop smoke, then a radio to establish contact. They call the coast guard for assistance if necessary. The reporter does not like finding a customs aircraft on his tail. This happened again in the same aircraft just 2 weeks after the reported incident. The faulty transponder was fixed the same day as the reported incident. The reporter has not heard from the FAA on this matter.

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Original NASA ASRS Text

Title: VIOLATION OF FAR 91 PT 111 BY A UNITED STATES CUSTOMS ACFT IN PURSUIT OF ITS NORMAL DUTIES.

Narrative: AFTER COMPLETING OUR SEARCH AND RESCUE MISSION, WE TURNED N TOWARDS OPF. AFTER APPROX 20 MINS IN CRUISE, THE CAPT LOOKED TO HIS L AND NOTICED OUR AIRPLANE'S SHADOW, ALONG WITH THE SHADOW OF ANOTHER ACFT IN EXTREMELY CLOSE PROX TO OUR OWN. THE CAPT THEN ASKED ME TO LOOK AT OUR 5-6 O'CLOCK POS AND DETERMINE WHETHER OR NOT THERE WAS AN ACFT IN CLOSE PROX TO US. WHILE LOOKING BACK TOWARDS OUR TAIL SECTION, I SAW THE R WING OF ANOTHER AIRPLANE WHICH APPEARED TO BE TRAVELING DIRECTLY BEHIND US, AT THE SAME ALT, AND NO MORE THAN 50 FT AWAY. THE CAPT SEEMED CONCERNED ABOUT THIS UNIDENTED ACFT. IN ORDER TO TRY TO MAKE THIS ACFT MOVE AWAY, THE CAPT INITIATED A SERIES OF SMALL ROLLS IN OPPOSITE DIRECTION (ROCKING THE WINGS). AFTER THIS ACTION, THE ACFT MOVED TO OUR 5:30 POS, WHERE I OBSERVED THAT THE ACFT FOLLOWING US WAS A TWIN TURBOJET PWRED AIRPLANE, PRESUMABLY A CESSNA CITATION OPERATED BY UNITED STATES CUSTOMS. I INFORMED THE CAPT OF MY OBSERVATION, AND HE INSTRUCTED ME TO CONTACT OUR GND CTLR. I INFORMED THE GND CTLR OF OUR SIT, AND ASKED HIM TO RELAY OUR SIT TO THE UNITED STATES CUSTOMS OFFICE. DURING THE INTERCEPT, THE AIRPLANE (ASSUMED NOW TO BE CUSTOMS), REMAINED AT OUR 5:30 POS IN DANGEROUSLY CLOSE PROX. AFTER APPARENTLY READING OUR TAIL NUMBER, THE ACFT DISAPPEARED. THE AIRPLANE WAS IN CLOSE PROX FOR APPROX 2 MINS THAT WE KNOW OF. AS A PRECAUTIONARY MEASURE, WE ASKED OUR GND CTLR TO INFORM OPF TWR THAT WE WOULD BE LNDG WITH AN INOP XPONDER. WHEN WE APCHED OPF AIRSPACE, THE ATC CTLR CONFIRMED THAT OUR XPONDER WAS INOP. AFTER LNDG, OUR GND CTLR CONFIRMED THAT THE ACFT WHICH INTERCEPTED US WAS A UNITED STATES CUSTOMS ACFT. THE AIRPLANE WHICH INTERCEPTED US DID NOT ATTEMPT AIR-TO-AIR CONTACT ON 122.75 MHZ, NOR DID THEY GIVE HAND SIGNALS OR ACFT MOTION SIGNALS AS PRESCRIBED IN AIM PARAGRAPH 5-90, 5-91, OR TABLE 5-93 OF THE SAME. IN ADDITION, THEY DID NOT ATTEMPT ANY SORT OF COM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE CESSNA SKYMASTER FOR A VOLUNTEER ORGANIZATION THAT HELPS IN THE SEARCH AND RESCUE OF CUBAN BOAT PEOPLE. HIS ORGANIZATION CALLS CUSTOMS BEFORE DEPARTING FOR A SEARCH MISSION AND THE PLTS ARE ON A CORDIAL BASIS WITH CUSTOMS. WHEN THEY FIND A BOAT OR RAFT, THEY DROP SMOKE, THEN A RADIO TO ESTABLISH CONTACT. THEY CALL THE COAST GUARD FOR ASSISTANCE IF NECESSARY. THE RPTR DOES NOT LIKE FINDING A CUSTOMS ACFT ON HIS TAIL. THIS HAPPENED AGAIN IN THE SAME ACFT JUST 2 WKS AFTER THE RPTED INCIDENT. THE FAULTY XPONDER WAS FIXED THE SAME DAY AS THE RPTED INCIDENT. THE RPTR HAS NOT HEARD FROM THE FAA ON THIS MATTER.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.