The pilot reported that during take-off, he opened the balloon's smart vent to reduce the rate of climb to ensure that the balloon remained clear of others in the near vicinity. He reported that the vent appeared to only partially open to approximately 6 inches. He had intended to vent for only 2 to 3 seconds. However, when he pulled on the line to close the vent, the vent would not close and reseal. Each time he pulled on the line the bottom sides of the envelope, where there are pulleys for the lines to run through, would draw to the centre of the balloon envelope. This indicated that there was a malfunction and the line was unable to freely move through the pulley.
The balloon continued to climb to approximately 55 ft where it levelled off. The pilot applied double burners for approximately 6 seconds but the balloon did not respond to the heating. The balloon began to descend and the pilot decided not to make any more burns. As the balloon accelerated towards the ground, he instructed his passengers to bend their knees and about 3 seconds after, the balloon landed heavily injuring some passengers.
When the balloon landed heavily, the smart vent closed. The vent was tested after the accident and was found to operate correctly. It has since continued to operate normally.
The operator reported that the smart vent was a relatively new invention and was still being developed. The operator also reported that there was an understanding within the company that the vent would not be operated until the balloon was landing.
The operator is amending the company's operating documentation to include a requirement that the smart vent not be operated unless the balloon is within 20 ft of the ground.