Narrative:

Near miss with unidented objects, slc. Observation: while on left downwind for runway 34L slc, I observed something whiz past us on the left. Estimating its size is difficult as I have nothing in memory with which to compare, but I estimate it at 4-6 ft high. Initially, I thought it was a light aircraft, then I thought it was a bird. I then observed sunlight glinting off the lower portion of the object. As I observed it pass, I realized how close we had come to it. My first officer and the acm asked what I saw. Before I could reply, I observed another similar object whiz by on our right. The first object was approximately 10-20 ft below our flight path. I called out and pointed. This time I could clearly see that it was a metal object suspended by a cluster of 2 or 3 balloons. They were nearly the same color as the setting sun -- a pinkish flesh color. My first officer and the acm called them out also, but when I looked, they were looking slightly below our flight path. They observed 2 additional balloon objects. We all agreed they were observing different objects than I. Between my crew, and myself we observed 4 objects in close proximity to our aircraft. A definite hazard to air navigation! Position: we had just been cleared out of 10000 ft (to 8000 ft I believe) when we encountered the objects. I estimate 9900 ft MSL. We were on an assigned heading of 165 degrees and were about 1 1/2 mi south of a point abeam the touchdown end of runway 34L. Conclusion: I assisted a FSS (many yrs ago) launch WX balloons. I do not believe these objects to be FSS WX balloons. A high school science project gone awry, perhaps?

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Original NASA ASRS Text

Title: FLC OF B757-200 SIGHTS UNUSUAL OBJECTS IN CLOSE ENOUGH PROX TO CONCERN THEM FOR POSSIBLE COLLISION. OBJECTS SIGHTED ABOVE AND BELOW THE ACFT.

Narrative: NEAR MISS WITH UNIDENTED OBJECTS, SLC. OBSERVATION: WHILE ON L DOWNWIND FOR RWY 34L SLC, I OBSERVED SOMETHING WHIZ PAST US ON THE L. ESTIMATING ITS SIZE IS DIFFICULT AS I HAVE NOTHING IN MEMORY WITH WHICH TO COMPARE, BUT I ESTIMATE IT AT 4-6 FT HIGH. INITIALLY, I THOUGHT IT WAS A LIGHT ACFT, THEN I THOUGHT IT WAS A BIRD. I THEN OBSERVED SUNLIGHT GLINTING OFF THE LOWER PORTION OF THE OBJECT. AS I OBSERVED IT PASS, I REALIZED HOW CLOSE WE HAD COME TO IT. MY FO AND THE ACM ASKED WHAT I SAW. BEFORE I COULD REPLY, I OBSERVED ANOTHER SIMILAR OBJECT WHIZ BY ON OUR R. THE FIRST OBJECT WAS APPROX 10-20 FT BELOW OUR FLT PATH. I CALLED OUT AND POINTED. THIS TIME I COULD CLRLY SEE THAT IT WAS A METAL OBJECT SUSPENDED BY A CLUSTER OF 2 OR 3 BALLOONS. THEY WERE NEARLY THE SAME COLOR AS THE SETTING SUN -- A PINKISH FLESH COLOR. MY FO AND THE ACM CALLED THEM OUT ALSO, BUT WHEN I LOOKED, THEY WERE LOOKING SLIGHTLY BELOW OUR FLT PATH. THEY OBSERVED 2 ADDITIONAL BALLOON OBJECTS. WE ALL AGREED THEY WERE OBSERVING DIFFERENT OBJECTS THAN I. BTWN MY CREW, AND MYSELF WE OBSERVED 4 OBJECTS IN CLOSE PROX TO OUR ACFT. A DEFINITE HAZARD TO AIR NAV! POS: WE HAD JUST BEEN CLRED OUT OF 10000 FT (TO 8000 FT I BELIEVE) WHEN WE ENCOUNTERED THE OBJECTS. I ESTIMATE 9900 FT MSL. WE WERE ON AN ASSIGNED HDG OF 165 DEGS AND WERE ABOUT 1 1/2 MI S OF A POINT ABEAM THE TOUCHDOWN END OF RWY 34L. CONCLUSION: I ASSISTED A FSS (MANY YRS AGO) LAUNCH WX BALLOONS. I DO NOT BELIEVE THESE OBJECTS TO BE FSS WX BALLOONS. A HIGH SCHOOL SCIENCE PROJECT GONE AWRY, PERHAPS?

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.