Narrative:

We were on a vector heading to las VOR en route from lax to ord when the first officer saw an unidented airborne object pass overhead at a high rate of speed. It happened very quickly and no evasive action was taken. He was only able to get a glimpse of it, but thought it was a small red and white aircraft. He estimated the vertical distance at 100 ft. I was looking away at the time, but thought I saw a shadow pass by. There were no targets indicated on the TCASII. We advised ZLA and they indicated no targets appeared on their radar screen. In speculating what the object was, the first officer did not believe it was a WX balloon. The area we passed over is known for its glider activity, but normally, at much lower altitude. Restr area R-2515 for edwards air force base was within 10 NM, so it's possible that the object may have been of military origins.

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Original NASA ASRS Text

Title: NMAC.

Narrative: WE WERE ON A VECTOR HDG TO LAS VOR ENRTE FROM LAX TO ORD WHEN THE FO SAW AN UNIDENTED AIRBORNE OBJECT PASS OVERHEAD AT A HIGH RATE OF SPD. IT HAPPENED VERY QUICKLY AND NO EVASIVE ACTION WAS TAKEN. HE WAS ONLY ABLE TO GET A GLIMPSE OF IT, BUT THOUGHT IT WAS A SMALL RED AND WHITE ACFT. HE ESTIMATED THE VERT DISTANCE AT 100 FT. I WAS LOOKING AWAY AT THE TIME, BUT THOUGHT I SAW A SHADOW PASS BY. THERE WERE NO TARGETS INDICATED ON THE TCASII. WE ADVISED ZLA AND THEY INDICATED NO TARGETS APPEARED ON THEIR RADAR SCREEN. IN SPECULATING WHAT THE OBJECT WAS, THE FO DID NOT BELIEVE IT WAS A WX BALLOON. THE AREA WE PASSED OVER IS KNOWN FOR ITS GLIDER ACTIVITY, BUT NORMALLY, AT MUCH LOWER ALT. RESTR AREA R-2515 FOR EDWARDS AIR FORCE BASE WAS WITHIN 10 NM, SO IT'S POSSIBLE THAT THE OBJECT MAY HAVE BEEN OF MIL ORIGINS.

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.