Narrative:

We were in level flight at 1400' with a heading around 340 degrees. We were using pilotage to ensure that we were clear of the arsa at bwi. We had noted bowie racetrack off our right side. Then our attention was directed forward. In less than a minute our peripheral vision drew our attention to the right as a helicopter made evasive action by banking toward our rear and passing under us. We heard his rotor/engine noise as he passed. We did not have time to react. We do not know if he was in level flight, descending or climbing before the event. After he passed us, he seemed to be in level flight on a heading of approximately west. After his evasive maneuver, he seemed to yaw to look back at us. I am certain of our position because we were 1 mi south of an obsolete airport (beltsville) whose location is 12 NM from bwi on the 225 degree right (southwest of bwi). We had our transponder on which has encoding altimeter. The transponder was installed approximately 1 month before the event. We are not sure what could have been done to prevent the near miss. If the helicopter was above us and descending, we could not see him because of the high wing of our small aircraft. We looked to our right when we spotted the bowie racetrack. We did not notice him at that time. Our aircraft is equipped with white strobe lights which we did not have on at the time. We should have used our strobes and landing light. We were in the air for 3 hours before the event, but we were not lax in our scanning procedures.

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Original NASA ASRS Text

Title: NMAC BETWEEN GA-SMA AND GA-SMT.

Narrative: WE WERE IN LEVEL FLT AT 1400' WITH A HDG AROUND 340 DEGS. WE WERE USING PILOTAGE TO ENSURE THAT WE WERE CLR OF THE ARSA AT BWI. WE HAD NOTED BOWIE RACETRACK OFF OUR RIGHT SIDE. THEN OUR ATTN WAS DIRECTED FORWARD. IN LESS THAN A MINUTE OUR PERIPHERAL VISION DREW OUR ATTN TO THE RIGHT AS A HELI MADE EVASIVE ACTION BY BANKING TOWARD OUR REAR AND PASSING UNDER US. WE HEARD HIS ROTOR/ENG NOISE AS HE PASSED. WE DID NOT HAVE TIME TO REACT. WE DO NOT KNOW IF HE WAS IN LEVEL FLT, DSNDING OR CLBING BEFORE THE EVENT. AFTER HE PASSED US, HE SEEMED TO BE IN LEVEL FLT ON A HDG OF APPROX W. AFTER HIS EVASIVE MANEUVER, HE SEEMED TO YAW TO LOOK BACK AT US. I AM CERTAIN OF OUR POS BECAUSE WE WERE 1 MI S OF AN OBSOLETE ARPT (BELTSVILLE) WHOSE LOCATION IS 12 NM FROM BWI ON THE 225 DEG R (SW OF BWI). WE HAD OUR XPONDER ON WHICH HAS ENCODING ALTIMETER. THE XPONDER WAS INSTALLED APPROX 1 MONTH BEFORE THE EVENT. WE ARE NOT SURE WHAT COULD HAVE BEEN DONE TO PREVENT THE NEAR MISS. IF THE HELI WAS ABOVE US AND DSNDING, WE COULD NOT SEE HIM BECAUSE OF THE HIGH WING OF OUR SMA. WE LOOKED TO OUR RIGHT WHEN WE SPOTTED THE BOWIE RACETRACK. WE DID NOT NOTICE HIM AT THAT TIME. OUR ACFT IS EQUIPPED WITH WHITE STROBE LIGHTS WHICH WE DID NOT HAVE ON AT THE TIME. WE SHOULD HAVE USED OUR STROBES AND LNDG LIGHT. WE WERE IN THE AIR FOR 3 HRS BEFORE THE EVENT, BUT WE WERE NOT LAX IN OUR SCANNING PROCS.

Data retrieved from NASA's ASRS site as of August 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.