In late October last year, I had written the post, pictured to the left, about an NTSB investigation into the 29 September 2010 hydrogen balloon downing that had likely killed sport balloonists and adventurers Richard Abruzzo and Carol Rymer Davis over the Adriatic sea as they took part in a race.
At the time, they were presumed dead because neither the balloon nor its occupants had been found despite a significant search effort. Their sad end the likely reason it came about is now laid out in the NTSB final report, issued on Monday.
Turns out that the balloon and the remains of the crew were found by accident in December 2010 by a fishing vessel that snagged the balloon.
Despite ICAO rules that say an aircraft accident in international waters (which radar returns showed the balloon in fact, was) is to be investigated by the country in which the aircraft is registered (the US, in this case, as the balloon was N801NM), the Italian government stepped in an laid claim to the remnants and the investigation.
(UPDATE 28 October 2011 on how the investigation was handled. From an NTSB spokesman:
The Italians actually did not take over the investigation, they just claimed the wreckage, which is not all that uncommon when a potential criminal probe is launched. We see this occasionally outside the US. The Italians assisted us, but the NTSB conducted the investigation and made the determination of probable cause.)
Be that as it may, what the Italians found was this:
- According to communications transcripts from Italian air traffic control, in the last moments of the flight, the crew reported thunder and lightning in the vicinity of the balloon, that they were losing altitude due to the snow, and ultimately stated that they were descending very fast towards the sea.
- A technical advisor, appointed by the Prosecutor's Office in the Court of Lucia, Italy, who claimed jurisdiction over the wreckage and the crew's remains, determined that the balloon envelope revealed "thermal damage in the lower half of the envelope consistent with a lightning strike. Further examination revealed shredding in the lower half, and slices in the upper half consistent with a hydrogen detonation."
- He found that the basket was deformed by impact damage, but displayed "no evidence of thermal damage".
- The Italian report suggests the crew was fixated with winning the race, and had discounted an experienced weather forcaster's advice not to fly that particular route.
Taking all that into account, the NTSB made its own declaration as to the probable cause:
"The crew's intentional flight into known adverse weather conditions, which resulted in destruction of the balloon envelope by lightning strike and the subsequent uncontrolled descent to the sea."