Descending air carrier large transport nearly collided with a balloon at FL266.

Attributes
ACN	85994
Time
Date	198804
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : mod
State Reference	CA
Altitude	msl bound lower : 26600 msl bound upper : 26600
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	arrival star : star
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller military : 5 controller non radar : 2 controller radar : 4
ASRS Report	85994
Person 2
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	Other
Miss Distance	horizontal : 4 vertical : 0
Supplementary
Air Traffic Incident	other

Narrative:

While working large transport X to sfo on the mod 9 arrival, the flight crew advised they had passed within 4' of what appeared to be a WX balloon at FL266. I advised that I had no notices or reports on balloon activity. I was unable to advise the pilot of the possibility of balloon traffic because I had not received any prior notice of the release. Normally, this is the only way we have of knowing it could be there. The return from the balloon is usually inadequate for radar tracking or it is moving too slowly and is screened out by mti. Adequate notice of a release should be disseminated to the sector prior to launch to facilitate advisories to the aircraft involved. Additionally, pilots should be aware of ATC limitations in providing tracking of these balloons and the fact they ascend through the positive control area during their flight. Callback conversation with reporter revealed the following: the controller reporter gave the information concerning the close call with the balloon to his supervisor. He later found out that the center had not had prior information about the balloon launch. Reporter also stated that when a balloon is launched that will penetrate the positive control area, it usually has a battery operated transponder aboard. Such was not the case in this incident. Nobody knows where the balloon was launched or why notification was not given.

Original NASA ASRS Text

Title: DESCENDING ACR LGT NEARLY COLLIDED WITH A BALLOON AT FL266.

Narrative: WHILE WORKING LGT X TO SFO ON THE MOD 9 ARR, THE FLT CREW ADVISED THEY HAD PASSED WITHIN 4' OF WHAT APPEARED TO BE A WX BALLOON AT FL266. I ADVISED THAT I HAD NO NOTICES OR RPTS ON BALLOON ACTIVITY. I WAS UNABLE TO ADVISE THE PLT OF THE POSSIBILITY OF BALLOON TFC BECAUSE I HAD NOT RECEIVED ANY PRIOR NOTICE OF THE RELEASE. NORMALLY, THIS IS THE ONLY WAY WE HAVE OF KNOWING IT COULD BE THERE. THE RETURN FROM THE BALLOON IS USUALLY INADEQUATE FOR RADAR TRACKING OR IT IS MOVING TOO SLOWLY AND IS SCREENED OUT BY MTI. ADEQUATE NOTICE OF A RELEASE SHOULD BE DISSEMINATED TO THE SECTOR PRIOR TO LAUNCH TO FACILITATE ADVISORIES TO THE ACFT INVOLVED. ADDITIONALLY, PLTS SHOULD BE AWARE OF ATC LIMITATIONS IN PROVIDING TRACKING OF THESE BALLOONS AND THE FACT THEY ASCEND THROUGH THE PCA DURING THEIR FLT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: THE CTLR RPTR GAVE THE INFO CONCERNING THE CLOSE CALL WITH THE BALLOON TO HIS SUPVR. HE LATER FOUND OUT THAT THE CENTER HAD NOT HAD PRIOR INFO ABOUT THE BALLOON LAUNCH. RPTR ALSO STATED THAT WHEN A BALLOON IS LAUNCHED THAT WILL PENETRATE THE PCA, IT USUALLY HAS A BATTERY OPERATED TRANSPONDER ABOARD. SUCH WAS NOT THE CASE IN THIS INCIDENT. NOBODY KNOWS WHERE THE BALLOON WAS LAUNCHED OR WHY NOTIFICATION WAS NOT GIVEN.

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.