Narrative:

While flying 'due regard' VFR at FL275 on return from a coast guard low enforcement patrol in the yucatan channel en route NAS key west (knqx) we had to execute evasive action to miss air carrier Y, an medium large transport. We were not on an IFR/VFR flight plan due to the mission. This is routine for the coast guard to enable us to transit to and from our patrol areas without announcing it to the world. We were monitoring havana center frequency on 135.1 MHZ and had heard the medium large transport airliner check in at canoa intersection at FL280. The cp, navigator and myself discussed this and were expecting to see him (coming opposite direction) at any moment since our flight path was taking us to canoa. Within minutes the cp saw the medium large transport and took evasive action. He was in the pilot's seat in control of the aircraft at the time. The medium large transport also took evasive to avoid us (sharp left turn). He appeared to be level with us. After resuming track we contacted miami center on 132.2 MHZ to pick up our previously filed IFR clearance to nqx. We were approximately 20 NM out of canoa at this time (canoa is the miami fir boundary). We notified miami of the incident. Once on dade ground control told us to contact the FAA in miami. I called (name) and answered his questions. Havana center told him the medium large transport saw us and thought we were at his altitude so he descended, then realized we really were at his new altitude (FL275) and took evasive action. The situation could be avoided by us filing an IFR flight plan the entire route, however, our operational mission dictates some secrecy. If he had kept his assigned altitude there would have been no problem at all. We were vigilant in flying a VFR altitude and in monitoring the local center frequency to keep us aware of nearby traffic.

Google
 

Original NASA ASRS Text

Title: MIL MLT HAS A NEAR MISS WITH AN ACR OVER WATER.

Narrative: WHILE FLYING 'DUE REGARD' VFR AT FL275 ON RETURN FROM A COAST GUARD LOW ENFORCEMENT PATROL IN THE YUCATAN CHANNEL ENRTE NAS KEY WEST (KNQX) WE HAD TO EXECUTE EVASIVE ACTION TO MISS ACR Y, AN MLG. WE WERE NOT ON AN IFR/VFR FLT PLAN DUE TO THE MISSION. THIS IS ROUTINE FOR THE COAST GUARD TO ENABLE US TO TRANSIT TO AND FROM OUR PATROL AREAS WITHOUT ANNOUNCING IT TO THE WORLD. WE WERE MONITORING HAVANA CENTER FREQ ON 135.1 MHZ AND HAD HEARD THE MLG AIRLINER CHECK IN AT CANOA INTXN AT FL280. THE CP, NAVIGATOR AND MYSELF DISCUSSED THIS AND WERE EXPECTING TO SEE HIM (COMING OPPOSITE DIRECTION) AT ANY MOMENT SINCE OUR FLT PATH WAS TAKING US TO CANOA. WITHIN MINUTES THE CP SAW THE MLG AND TOOK EVASIVE ACTION. HE WAS IN THE PLT'S SEAT IN CONTROL OF THE ACFT AT THE TIME. THE MLG ALSO TOOK EVASIVE TO AVOID US (SHARP LEFT TURN). HE APPEARED TO BE LEVEL WITH US. AFTER RESUMING TRACK WE CONTACTED MIAMI CENTER ON 132.2 MHZ TO PICK UP OUR PREVIOUSLY FILED IFR CLRNC TO NQX. WE WERE APPROX 20 NM OUT OF CANOA AT THIS TIME (CANOA IS THE MIAMI FIR BOUNDARY). WE NOTIFIED MIAMI OF THE INCIDENT. ONCE ON DADE GND CTL TOLD US TO CONTACT THE FAA IN MIAMI. I CALLED (NAME) AND ANSWERED HIS QUESTIONS. HAVANA CENTER TOLD HIM THE MLG SAW US AND THOUGHT WE WERE AT HIS ALT SO HE DESCENDED, THEN REALIZED WE REALLY WERE AT HIS NEW ALT (FL275) AND TOOK EVASIVE ACTION. THE SITUATION COULD BE AVOIDED BY US FILING AN IFR FLT PLAN THE ENTIRE ROUTE, HOWEVER, OUR OPERATIONAL MISSION DICTATES SOME SECRECY. IF HE HAD KEPT HIS ASSIGNED ALT THERE WOULD HAVE BEEN NO PROBLEM AT ALL. WE WERE VIGILANT IN FLYING A VFR ALT AND IN MONITORING THE LCL CENTER FREQ TO KEEP US AWARE OF NEARBY TFC.

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.