Aviation Accident Summaries

Aviation Accident Summary WPR12LA138

Avra Valley, AZ, USA

Aircraft #1

N57194

RAVEN INDUSTRIES INC S-66A

Analysis

The pilot reported that the balloon was traveling 5 to 7 knots west toward a road oriented north-south with a power line running along the east side of the road. Beyond the power line and road was a large area of open desert where the pilot planned to land. When the balloon was about 100 yards from the lines at an altitude of about 300 feet above ground level, the pilot began setting the balloon up for landing by cracking open the vent-top of the envelope. The pilot operated one of the two burners to compensate for the expected loss of lift from the partly open top; however, the balloon began a slow descent instead of maintaining altitude, and the descent rate seemed to accelerate. In response, the pilot operated both burners and looked up at the top of the balloon, which he found was over a third open instead of the expected 2- to 3-foot crack. Realizing that the balloon’s glidepath would now result in the basket impacting the upper wire of the power line, the pilot decided to fully open the top of the balloon and land short of the power line. The balloon descended and impacted the power line wires with the basket suspension cables contacting more than one wire, which resulted in electrical arcing. The envelope folded over the wires, and the basket came to rest on the ground. The pilot stated that the accident could have been prevented by initiating the set-up for landing only after crossing the last obstacle before the landing area.

Factual Information

On March 16, 2012, about 0800 mountain standard time, a Raven Industries, Inc., S-66A balloon, N57194, was substantially damaged when its envelope contacted electrical transmission lines during landing near Avra Valley, Arizona. The commercial pilot and two passengers received minor injuries, and the other six passengers were not injured. The balloon was registered to an individual, and doing business as Southern Arizona Balloon Excursions, under the provisions of 14 Code of Federal Regulations Part 91. A flight plan had not been filed for the local area sightseeing flight, which had originated from Marana, Arizona, about 0630. Visual meteorological conditions prevailed at the time of the accident. The pilot reported that the balloon was traveling west at a speed of 5 to 7 knots towards a road oriented north-south with a power line running along the east side of the road. Beyond the power line and road was a large area of open desert where the pilot planned to land. When the balloon was about 100 yards from the lines at an altitude of about 300 feet above ground level (agl), he began setting the balloon up for landing by “cracking open the vent-top of the envelope to set up a “heavy” condition for landing.” The pilot operated one of the two burners to compensate for the loss of lift from the partly open top; however, the balloon began a slow descent instead of maintaining altitude, and the descent rate seemed to accelerate. In response, the pilot operated both burners and looked up at the top of the balloon, which he found was “over a third open instead of the expected 2-3 foot opening.” Realizing that the balloon’s glide path would now result in the basket impacting the upper wire of the power line, he decided to fully open the top of the balloon and land short of the power line. The balloon descended and impacted the power line wires with the basket suspension cables contacting more than one wire resulting in electrical arcing. Pieces of burning balloon envelope material rained down into the basket. The envelope folded over the wires, and the basket came to rest on the ground. Three suspension cables were separated and several envelope panels were damaged. In the section of the National Transportation Safety Board Pilot/Operator Aircraft Accident Report titled “Recommendation (How could this accident/incident have been prevented?),” the pilot stated, “when operating LTA [lighter than air] aircraft initiate set-up for landing sequence only after crossing last obstacle prior to landing field/area.”

Probable Cause and Findings

The pilot's improper decision to partially open the balloon's vent before clearing a power line while landing, which resulted in the balloon descending too soon and contacting the power line.

 

Source: NTSB Aviation Accident Database

Get all the details on your iPhone or iPad with:

Aviation Accidents App

In-Depth Access to Aviation Accident Reports