Narrative:

20 mi east of bwi, I avoided a midair collision. I was serving as first officer aboard airlines flight bdr to bwi. Before the occurrence, captain was the PF, and I was performing the PNF duties. Baltimore approach assigned us 2500' MSL, and we descended from 3000' to comply. We had just leveled off at 2500' when I sighted an small aircraft white with brown trim, approaching nearly head on, at our altitude and 12 O'clock position, becoming visible in the haze, only a few hundred (approximately 200) feet away. I told the captain, 'traffic 12 O'clock! I've got it', and assumed control of the aircraft, rolling into a descending right turn. Once the captain saw the small aircraft, he reassumed control and further banked the aircraft. The small aircraft passed within 50-100' to our left and slightly above, heading approximately 120 degree. (Our original heading was approximately 270 degree). The small aircraft did not appear to take any evasive action. Our evasive action resulted in a deviation down to 2200' MSL. This occurrence was immediately brought to the controller's attention, and he replied the other aircraft was not on his radar. We filed a near miss report with ATC after landing at bwi. None of the 15 passenger on board were hurt, though some witnessed the small aircraft out the left side windows. Flight visibility was approximately 4 mi in haze. Bwi was reporting 7 SM ground visibility (ATIS information). Suggestion: keep IFR traffic above 3000' MSL this far out. Supplemental information from acn 111984: the controller said that nothing was shown on radar.

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Original NASA ASRS Text

Title: CLOSE PROX ACR-LTT GA-SMA 20 EAST OF BWI.

Narrative: 20 MI E OF BWI, I AVOIDED A MIDAIR COLLISION. I WAS SERVING AS F/O ABOARD AIRLINES FLT BDR TO BWI. BEFORE THE OCCURRENCE, CAPT WAS THE PF, AND I WAS PERFORMING THE PNF DUTIES. BALTIMORE APCH ASSIGNED US 2500' MSL, AND WE DESCENDED FROM 3000' TO COMPLY. WE HAD JUST LEVELED OFF AT 2500' WHEN I SIGHTED AN SMA WHITE WITH BROWN TRIM, APCHING NEARLY HEAD ON, AT OUR ALT AND 12 O'CLOCK POSITION, BECOMING VISIBLE IN THE HAZE, ONLY A FEW HUNDRED (APPROX 200) FEET AWAY. I TOLD THE CAPT, 'TFC 12 O'CLOCK! I'VE GOT IT', AND ASSUMED CONTROL OF THE ACFT, ROLLING INTO A DESCENDING RIGHT TURN. ONCE THE CAPT SAW THE SMA, HE REASSUMED CONTROL AND FURTHER BANKED THE ACFT. THE SMA PASSED WITHIN 50-100' TO OUR LEFT AND SLIGHTLY ABOVE, HDG APPROX 120 DEG. (OUR ORIGINAL HDG WAS APPROX 270 DEG). THE SMA DID NOT APPEAR TO TAKE ANY EVASIVE ACTION. OUR EVASIVE ACTION RESULTED IN A DEVIATION DOWN TO 2200' MSL. THIS OCCURRENCE WAS IMMEDIATELY BROUGHT TO THE CTLR'S ATTN, AND HE REPLIED THE OTHER ACFT WAS NOT ON HIS RADAR. WE FILED A NEAR MISS REPORT WITH ATC AFTER LNDG AT BWI. NONE OF THE 15 PAX ON BOARD WERE HURT, THOUGH SOME WITNESSED THE SMA OUT THE LEFT SIDE WINDOWS. FLT VISIBILITY WAS APPROX 4 MI IN HAZE. BWI WAS REPORTING 7 SM GND VISIBILITY (ATIS INFO). SUGGESTION: KEEP IFR TFC ABOVE 3000' MSL THIS FAR OUT. SUPPLEMENTAL INFORMATION FROM ACN 111984: THE CTLR SAID THAT NOTHING WAS SHOWN ON RADAR.

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.