Narrative:

I was inbound for landing at dupage airport from the west. I called in 10 mi out and received 'left downwind for runway 28, report the river.' at the river, I called, and got no response. 1/2 mi later, I tried again, and was cleared to land, runway 28. Shortly thereafter, as I was on left downwind, (eastbound), a plane (that apparently had taken off from dpa) crossed from left to right, right in front of me, (sbound) same altitude, a few hundred ft ahead. I saw the other plane and was able to cross behind him. I don't know exactly how this close call came to happen, but somehow the tower sequencing had to be involved, unless the other plane was somewhere they were not supposed to be. I don't recall the tower's interactions with that plane through its takeoff.

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Original NASA ASRS Text

Title: AN EXPERIMENTAL ACFT HAS AN NMAC WITH A PIPER AT DPA.

Narrative: I WAS INBOUND FOR LNDG AT DUPAGE ARPT FROM THE W. I CALLED IN 10 MI OUT AND RECEIVED 'L DOWNWIND FOR RWY 28, RPT THE RIVER.' AT THE RIVER, I CALLED, AND GOT NO RESPONSE. 1/2 MI LATER, I TRIED AGAIN, AND WAS CLRED TO LAND, RWY 28. SHORTLY THEREAFTER, AS I WAS ON L DOWNWIND, (EBOUND), A PLANE (THAT APPARENTLY HAD TAKEN OFF FROM DPA) CROSSED FROM L TO R, RIGHT IN FRONT OF ME, (SBOUND) SAME ALT, A FEW HUNDRED FT AHEAD. I SAW THE OTHER PLANE AND WAS ABLE TO CROSS BEHIND HIM. I DON'T KNOW EXACTLY HOW THIS CLOSE CALL CAME TO HAPPEN, BUT SOMEHOW THE TWR SEQUENCING HAD TO BE INVOLVED, UNLESS THE OTHER PLANE WAS SOMEWHERE THEY WERE NOT SUPPOSED TO BE. I DON'T RECALL THE TWR'S INTERACTIONS WITH THAT PLANE THROUGH ITS TKOF.

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.