Incident at The Pas, MB (Conflict - potential)


1999-02-23: DARR 92, a KC-135, was enroute from Beale AFB to RAF Mildenhall and was overhead The Pas at FL 290 when the crew reported a large balloon about 2,000 feet below them. UAL 930, a B777, was 30 miles behind DARR 92 enroute to Heathrow and the crew was passed the information. The crew of UAL 930 requested vectors around the balloon, however, Winnipeg ACC did not have it on radar, so the crew was cleared to deviate at their discretion. UAL 930 deviated about 10 miles to the north of The Pas, but reported that they did not see the balloon. It was later confirmed that the position and altitude of the balloon coincided with a radiosonde balloon launched from The Pas by Environment Canada. These balloons do not carry transponders and the launches are not reported by NOTAM. Winnipeg ACC was unaware of the presence of the balloon and was unable to advise the crews of a/c flying through the area. It was reported that the balloons climb as high as 100,000 feet before self-destructing and falling back to earth. It has been a longstanding concern of NavCanada staff that there is very little co-ordination of these launches between Environment Canada and NavCanada. OPI - ANS and Airspace UPDATE TSB reported that the balloon was launched from the Atmospheric Environmental Service (AES) facility at The Pas about 1/2 hour before the incident. The balloon was carrying a Loran MK II microsonde that weighs about one pound. The balloon is designed to ascend to 80,000 feet at 1000 feet per minute and then burst. AES reported that this balloon reached about 116,000 feet. Because it has a gas-carrying capacity of less than 115 cubic feet, it is not regulated under CARS 602.42. These types of balloons are launched twice daily from multiple sites in Canada and the U.S.


CADORS Number 1999C0116
Occurrence Type Incident
Reported By NAV CANADA
Occurred At 1999-02-16 - 23:41
Day or Night? Day-time
Fatalities 0
Aerodrome ID
Aerodrome Name
Geographic Location Manitoba, Canada, North America, Prairie and Northern Region, The Pas, MB
TSB Occurrence Number
TSB Class of Investigation
AOR Number
Reported By NAV CANADA
Categories Airprox/TCAS alert/loss of separation/(near) midair collisions
Events Conflict - potential

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