Narrative:

Departed gate., taxied to runway 28. As we taxied out tower cleared small aircraft Y for takeoff on runway 33R. We thought nothing of it. Apparently tower cleared Y for a left downwind departure. Tower cleared us to takeoff with turn to 220 degrees from runway 28. As we rolled tower pointed us out to small aircraft Y, and called us in sight. We still had no idea that small aircraft Y was on left downwind coming our way! Normal takeoff and initial climb to 400' AGL. 400', flaps up, I started my turn to 220 degrees, just at the intersection of runways 28 and 33L. As I rolled into left turn I saw small aircraft Y heading down the center line of runways 15L and 33R, straight for us. I steepened bank. Aircraft Y also banked to his left, passing 500' to our right, at our altitude! Tower never said a word. I asked where aircraft Y came from and was told he had us in sight! If I had misunderstood heading and turned to 320 degrees, we would have collided right there in bwi's laps! ATC should have advised us of aircraft Y and/or had Y do right turn departure.

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Original NASA ASRS Text

Title: NMAC BETWEEN MDT-ACR AND SMA. OPERATIONAL ERROR.

Narrative: DEPARTED GATE., TAXIED TO RWY 28. AS WE TAXIED OUT TWR CLRED SMA Y FOR TKOF ON RWY 33R. WE THOUGHT NOTHING OF IT. APPARENTLY TWR CLRED Y FOR A LEFT DOWNWIND DEP. TWR CLRED US TO TKOF WITH TURN TO 220 DEGS FROM RWY 28. AS WE ROLLED TWR POINTED US OUT TO SMA Y, AND CALLED US IN SIGHT. WE STILL HAD NO IDEA THAT SMA Y WAS ON LEFT DOWNWIND COMING OUR WAY! NORMAL TKOF AND INITIAL CLB TO 400' AGL. 400', FLAPS UP, I STARTED MY TURN TO 220 DEGS, JUST AT THE INTXN OF RWYS 28 AND 33L. AS I ROLLED INTO LEFT TURN I SAW SMA Y HEADING DOWN THE CENTER LINE OF RWYS 15L AND 33R, STRAIGHT FOR US. I STEEPENED BANK. ACFT Y ALSO BANKED TO HIS LEFT, PASSING 500' TO OUR RIGHT, AT OUR ALT! TWR NEVER SAID A WORD. I ASKED WHERE ACFT Y CAME FROM AND WAS TOLD HE HAD US IN SIGHT! IF I HAD MISUNDERSTOOD HDG AND TURNED TO 320 DEGS, WE WOULD HAVE COLLIDED RIGHT THERE IN BWI'S LAPS! ATC SHOULD HAVE ADVISED US OF ACFT Y AND/OR HAD Y DO RIGHT TURN DEP.

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.