A military KC10 reports an near midair collision with what appeared to be a WX balloon.

Attributes
ACN	351052
Time
Date	199607
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : oal
State Reference	NV
Altitude	msl bound lower : 25000 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	other
Make Model Name	DC-10 Undifferentiated or Other Model
Operating Under FAR Part	other : other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : military
Function	flight crew : captain oversight : pic
Qualification	pilot : military
Experience	flight time last 90 days : 100 flight time total : 2900 flight time type : 2500
ASRS Report	351052
Person 2
Affiliation	government : military
Function	flight crew : first officer
Qualification	pilot : military
Events
Anomaly	conflict : nmac other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	Other
Miss Distance	horizontal : 100 vertical : 0
Supplementary
Primary Problem	Chart Or Publication

Narrative:

During cruise at FL250, we flew by what appeared to be a WX balloon. It was a balloon wide at the top and narrow at the bottom. It was at our level and passed our left wing by only about 100 ft away. It could have gone down the engine or got caught on the wing creating problems. There should be better information distributed about when and where WX balloons are used.

Original NASA ASRS Text

Title: A MIL KC10 RPTS AN NMAC WITH WHAT APPEARED TO BE A WX BALLOON.

Narrative: DURING CRUISE AT FL250, WE FLEW BY WHAT APPEARED TO BE A WX BALLOON. IT WAS A BALLOON WIDE AT THE TOP AND NARROW AT THE BOTTOM. IT WAS AT OUR LEVEL AND PASSED OUR L WING BY ONLY ABOUT 100 FT AWAY. IT COULD HAVE GONE DOWN THE ENG OR GOT CAUGHT ON THE WING CREATING PROBS. THERE SHOULD BE BETTER INFO DISTRIBUTED ABOUT WHEN AND WHERE WX BALLOONS ARE USED.

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.