RESEARCH C130 LOW LEVEL CALIBRATION FLT OVER A LAKE RAISES SECURITY CONCERNS BY DAM PERSONNEL.

Narrative

AFTER COMPLETING ATMOSPHERE RESEARCH; APPROX 3 NM N OF THE LAKE; WE DSNDED TO 1000 FT AGL TO SET UP AN ONBOARD SCIENTIFIC INST CALIBRATION RUN OVER THE WATER. APPROX 1/4 MI N OF THE LAKE; WE NOTICED THAT THE TERRAIN DROPPED SHARPLY AT THE LAKE'S EDGE (BACK). WE DSNDED OVER THE LAKE'S N BANK TO MAINTAIN 1000 FT AGL. AS WE FLEW TOWARDS THE S BANK OF THE LAKE; WE REALIZED THE TERRAIN ROSE SLIGHTLY WHICH PLACED THE ACFT AT 600 FT AGL AS WE PASSED OVER THE SOUTHERN SHORELINE. WE BEGAN A CLBING R TURN BACK TO THE NW TO SET UP ONE FINAL CALIBRATION RUN OVER THE SAME TRACK USING THE SAME ALT PROFILE. ALTHOUGH WE BRIEFLY WERE AT 600 FT AGL; THE C130 IS A LARGE ACFT AND MAY APPEAR TO BE LOWER THAN IT ACTUALLY IS WHEN VIEWED FROM THE GND. IN RETROSPECT; A CALL TO THE BUREAU OF RECLAMATION IN CHARGE OF THE DAM; BEFORE OUR FLT; WOULD HAVE PRECLUDED ANY CONCERN OF POSSIBLE DAMAGE TO THE DAM; ESPECIALLY IN LIGHT OF SEP/11 EVENTS. WE WILL ALSO CONDUCT FUTURE CALIBRATION FLTS AT 1500 FT AGL; ALLOWING MORE BUFFER FOR TERRAIN FEATURES. SUPPLEMENTAL INFO FROM ACN 594538: WE HAD A COMPLAINT FROM BUREAU OF RECLAMATION IN CHARGE OF THE DAM. THEY FEARED WE WERE GOING TO CAUSE DAMAGE TO THE DAM.