Narrative:

The last tether ride of the evening had been completed and the last 2 passenger (weighing approximately 370 pounds) had left the balloon basket. I was briefing the ground crew members on how to maneuver the balloon upwind when a mild gust of wind, called 'false lift,' picked up the 4 members of the ground crew (whose weight was approximately 740 pounds). The 2 to my back side immediately let go and the 2 to my front side held on until the balloon was approximately 30 ft in the air. I instructed them to hang on as I vented the top to allow us to descend to the ground. One of the crew members lost his grip and fell approximately 25 ft, breaking his left ankle and left arm. I had experienced 'false lifts' 2 or 3 times during the tether rides, winds were sustained at approximately 240 degrees between 4-5 KTS, with winds occasionally increasing to 7 or 8 KTS. I have experienced 'false lifts' before but never to the extent that it would pick up ground crew members of that weight. My advice to other balloonists conducting tether operations is to be careful with even mild changes in wind velocity because of danger of 'false lifts.' callback conversation with reporter revealed the following: the reporting pilot is an FAA designated examiner and airport manager. He does balloon work on the side. The balloon was properly tied down on a football field for the tether operation. 4 people were holding onto the basket at the conclusion of the operation. Their task was to move the basket upwind away from a goal post so that the balloon could be deflated without contacting the posts. One of the 4 ground crew lifted the basket manually when a gust also lifted the balloon. The balloon became very light and lifted the 2 people hanging onto the outside of the basket. The pilot chose to vent the balloon rather than try to hang on to the crew men outside the basket. Unfortunately, one of the crew men had a poor grip and fell to the ground. The reporting pilot agrees that 'false lift' is poorly named as it is very real aerodynamic lift caused by a higher velocity wind over the top of the balloon as opposed to the normal aerostatic lift caused by a temperature or density difference between the inside and outside of the envelope. The reporter notified the local FSDO of this incident the following day. He has heard nothing since from them.

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Original NASA ASRS Text

Title: A BALLOON GND CREW MAN WAS INJURED WHEN A TETHERED BALLOON LIFTED IN GUSTY CONDITIONS.

Narrative: THE LAST TETHER RIDE OF THE EVENING HAD BEEN COMPLETED AND THE LAST 2 PAX (WEIGHING APPROX 370 LBS) HAD LEFT THE BALLOON BASKET. I WAS BRIEFING THE GND CREW MEMBERS ON HOW TO MANEUVER THE BALLOON UPWIND WHEN A MILD GUST OF WIND, CALLED 'FALSE LIFT,' PICKED UP THE 4 MEMBERS OF THE GND CREW (WHOSE WT WAS APPROX 740 LBS). THE 2 TO MY BACK SIDE IMMEDIATELY LET GO AND THE 2 TO MY FRONT SIDE HELD ON UNTIL THE BALLOON WAS APPROX 30 FT IN THE AIR. I INSTRUCTED THEM TO HANG ON AS I VENTED THE TOP TO ALLOW US TO DSND TO THE GND. ONE OF THE CREW MEMBERS LOST HIS GRIP AND FELL APPROX 25 FT, BREAKING HIS L ANKLE AND L ARM. I HAD EXPERIENCED 'FALSE LIFTS' 2 OR 3 TIMES DURING THE TETHER RIDES, WINDS WERE SUSTAINED AT APPROX 240 DEGS BTWN 4-5 KTS, WITH WINDS OCCASIONALLY INCREASING TO 7 OR 8 KTS. I HAVE EXPERIENCED 'FALSE LIFTS' BEFORE BUT NEVER TO THE EXTENT THAT IT WOULD PICK UP GND CREW MEMBERS OF THAT WT. MY ADVICE TO OTHER BALLOONISTS CONDUCTING TETHER OPS IS TO BE CAREFUL WITH EVEN MILD CHANGES IN WIND VELOCITY BECAUSE OF DANGER OF 'FALSE LIFTS.' CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE RPTING PLT IS AN FAA DESIGNATED EXAMINER AND ARPT MGR. HE DOES BALLOON WORK ON THE SIDE. THE BALLOON WAS PROPERLY TIED DOWN ON A FOOTBALL FIELD FOR THE TETHER OP. 4 PEOPLE WERE HOLDING ONTO THE BASKET AT THE CONCLUSION OF THE OP. THEIR TASK WAS TO MOVE THE BASKET UPWIND AWAY FROM A GOAL POST SO THAT THE BALLOON COULD BE DEFLATED WITHOUT CONTACTING THE POSTS. ONE OF THE 4 GND CREW LIFTED THE BASKET MANUALLY WHEN A GUST ALSO LIFTED THE BALLOON. THE BALLOON BECAME VERY LIGHT AND LIFTED THE 2 PEOPLE HANGING ONTO THE OUTSIDE OF THE BASKET. THE PLT CHOSE TO VENT THE BALLOON RATHER THAN TRY TO HANG ON TO THE CREW MEN OUTSIDE THE BASKET. UNFORTUNATELY, ONE OF THE CREW MEN HAD A POOR GRIP AND FELL TO THE GND. THE RPTING PLT AGREES THAT 'FALSE LIFT' IS POORLY NAMED AS IT IS VERY REAL AERODYNAMIC LIFT CAUSED BY A HIGHER VELOCITY WIND OVER THE TOP OF THE BALLOON AS OPPOSED TO THE NORMAL AEROSTATIC LIFT CAUSED BY A TEMP OR DENSITY DIFFERENCE BTWN THE INSIDE AND OUTSIDE OF THE ENVELOPE. THE RPTR NOTIFIED THE LCL FSDO OF THIS INCIDENT THE FOLLOWING DAY. HE HAS HEARD NOTHING SINCE FROM THEM.

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.