Narrative:

Our company works in conjunction with the usda on the insect pest eradication program here in ZZZ, first officer. We release sterile flies over the country in grid or block patterns. In the past, when the WX necessitated an IFR flight plan, we were cleared to our dispersal region at an altitude with further clearance back to location. A change in ATC procedure requested a block from between 2 radials and 2 DME settings from ZZZ VOR while airborne. I gave the 2 radials between which I intended to fly and they cleared me to fly between those radials at 80-120 DME. I accepted. Later when I realized that the DME distances would not allow full coverage of my region, I requested an amendment for a bigger block and was given an extension. Towards the end of my block I was unsure of amended clearance coverage needed to overfly some nearby islands, so stated my intentions of flying to them. It was acknowledged and I was told to maintain my altitude. After leaving the original block, ATC informed me that I was not cleared to do so and I had violated my original clearance. I requested further clearance which was given and completed the flight. Contributing factors include: 1) spanish/english language barriers. 2) my assumption of being fully cleared to fly outside of an assigned block. 3) change in ATC procedure leading to ambiguity. 4) heavy traffic flow on ATC frequency. Corrective actions: our base is planning a visit to ATC to discuss effective procedures and any concerns.

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Original NASA ASRS Text

Title: BE90 PLT AND FOREIGN CTLR HAD LANGUAGE BARRIER, READBACK HEARBACK PROBS IN A FOREIGN LOCATION.

Narrative: OUR COMPANY WORKS IN CONJUNCTION WITH THE USDA ON THE INSECT PEST ERADICATION PROGRAM HERE IN ZZZ, FO. WE RELEASE STERILE FLIES OVER THE COUNTRY IN GRID OR BLOCK PATTERNS. IN THE PAST, WHEN THE WX NECESSITATED AN IFR FLT PLAN, WE WERE CLRED TO OUR DISPERSAL REGION AT AN ALT WITH FURTHER CLRNC BACK TO LOCATION. A CHANGE IN ATC PROC REQUESTED A BLOCK FROM BTWN 2 RADIALS AND 2 DME SETTINGS FROM ZZZ VOR WHILE AIRBORNE. I GAVE THE 2 RADIALS BTWN WHICH I INTENDED TO FLY AND THEY CLRED ME TO FLY BTWN THOSE RADIALS AT 80-120 DME. I ACCEPTED. LATER WHEN I REALIZED THAT THE DME DISTANCES WOULD NOT ALLOW FULL COVERAGE OF MY REGION, I REQUESTED AN AMENDMENT FOR A BIGGER BLOCK AND WAS GIVEN AN EXTENSION. TOWARDS THE END OF MY BLOCK I WAS UNSURE OF AMENDED CLRNC COVERAGE NEEDED TO OVERFLY SOME NEARBY ISLANDS, SO STATED MY INTENTIONS OF FLYING TO THEM. IT WAS ACKNOWLEDGED AND I WAS TOLD TO MAINTAIN MY ALT. AFTER LEAVING THE ORIGINAL BLOCK, ATC INFORMED ME THAT I WAS NOT CLRED TO DO SO AND I HAD VIOLATED MY ORIGINAL CLRNC. I REQUESTED FURTHER CLRNC WHICH WAS GIVEN AND COMPLETED THE FLT. CONTRIBUTING FACTORS INCLUDE: 1) SPANISH/ENGLISH LANGUAGE BARRIERS. 2) MY ASSUMPTION OF BEING FULLY CLRED TO FLY OUTSIDE OF AN ASSIGNED BLOCK. 3) CHANGE IN ATC PROC LEADING TO AMBIGUITY. 4) HVY TFC FLOW ON ATC FREQ. CORRECTIVE ACTIONS: OUR BASE IS PLANNING A VISIT TO ATC TO DISCUSS EFFECTIVE PROCS AND ANY CONCERNS.

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.