Tamarack hotly disputed that finding, and petitioned the NTSB to reconsider its probable cause determination in January 2022. The board's response arrived in a 12-page letter dated February 26, with the amended probable cause report attached.
In a rare (if not unprecedented) reversal the board wrote that Tamarack's petition "is granted in part because the available evidence for this accident does not sufficiently show that the ATLAS was the cause of the in-flight upset from which the pilot was unable to recover. In addition, the factual and analysis sections of the report and the findings have been revised to reflect the information presented in the petition response sections addressing witness marks, [control unit] bent pins, and the UK uncommanded roll event..."
The National Transportation Safety Board (NTSB) has revised its assessment of a 2018 fatal accident involving a Cessna CitationJet CJ2+ equipped with Tamarack winglets, reversing its position that the winglet design contributed to the crash.
The aircraft was equipped with Tamarack Aerospace Group’s active technology load alleviation system (ATLAS), which operated independently of other airplane systems.
The system included the installation of Tamarack active camber surfaces (TACS), which are aerodynamic control surfaces mounted on the wing extensions that either hold their position in trail with the wing or symmetrically deploy trailing edge up or trailing edge down to alleviate structural loads. The TACS are actuated by the TACS control units (TCUs) and are not controlled by the pilot.
The winglets are designed to improve aircraft stability and fuel efficiency.
The US National Transportation Safety Board (NTSB) has revised a 2021 accident report to remove a conclusion that Tamarack Aerospace’s Atlas active winglets caused a deadly Cessna Citation 525 crash in 2018.
“Available evidence for this accident does not sufficiently show that the Atlas [winglet system] was the cause of the in-flight upset from which the pilot was unable to recover,” the NTSB said in a 26 February letter to Idaho-based Tamarack.
Evidence is “insufficient to conclude” that the left winglet was extended at the time of impact or that the Atlas system caused the jet to roll left, it adds.
The National Transportation Safety Board (NTSB) retracted its initial determination that Tamarack Aerospace’s Atlas active winglets were the cause of a fatal Cessna Citation 525 crash in 2018.
In a revised report released Feb. 23, the agency attributed the crash to “the pilot’s inability to regain airplane control after a left roll that began for reasons that could not be determined based on the available evidence.” Previously, the NTSB said the Citation’s Tamarack winglets deployed asymmetrically, causing the jet to roll left and subsequently descend into the ground.
Following a petition for reconsideration by Tamarack Aerospace, the National Transportation Safety Board (NTSB) has issued a revised final report for the Nov. 30, 2018 crash of N525EG, a Cessna 525 CitationJet equipped with a Tamarack active winglet system. The new probable cause is: “The pilot’s inability to regain airplane control after a left roll that began for reasons that could not be determined based on the available evidence.”
The NTSB issued the original final report on the accident on Nov. 21, 2021. Tamarack submitted the petition for reconsideration in January 2022.
In a statement about the revision, Tamarack president Jacob Klinginsmith said, “Tamarack is very pleased that the NTSB has decided to grant our petition for reconsideration concerning this 2018 accident and taken steps to correct multiple technical errors in the original investigation. This reversal shows the NTSB has the courage, professionalism, and proper process to make these corrections, and for that, we applaud the NTSB. Our growing fleet of nearly 200 CitationJet customers see the safety, performance, and fuel-saving sustainability benefits of our technology on every flight. Our customers know that the active winglet upgrade is safe and reliable, and consistently brings a lot of value to Cessna CitationJets and other upgraded aircraft.
The NTSB report found that an electrical failure in the system likely caused one of the control surfaces to deploy separately, which caused an uncommanded roll. The pilot was not aware of any supplementary procedures, according to the findings. Further, the procedures did not explain the significance of the system failure nor did they address the failure in all flight conditions. Nearly six months after the crash, the FAA grounded all Cessna planes equipped with ATLAS winglets, which lifted in the summer of 2019 after Tamarack found a fix to improve the safety and reliability. After the report, Tamarack sent a petition to the NTSB to reconsider its findings, claiming they were inconsistent with the degree and timing of the TACS deflection and the evidence described, which could be linked with the force of impact, not necessarily indicating the position in flight.
The NTSB issued its final report in May 2021 and this was challenged by Tamarack in November 2021. The settlement with Tamarack with the families and representatives of the victims was settled in February 2023. Now, nearly three years after the final report was issued and a petition filed, the NTSB has reversed its findings.
The National Transportation Safety Board (NTSB) has just published a revised Aviation Investigation Final Report for a tragic aircraft accident that occurred in Indiana in 2018. In in a very unusual turn of events, this new report reverses a previous probable cause.
"…the available evidence for this accident does not sufficiently show that the ATLAS was the cause of the in-flight upset from which the pilot was unable to recover," states the NTSB in its formal response to the petition by Tamarack Aerospace Group, the developer of the Active Technology Load Alleviation System (ATLAS) wing modifications.
The response also states that "…the NTSB agrees with the petitioner that the evidence is also insufficient to conclude that (1) the left actuator was in an extended position at the time of initial impact and (2) the ATLAS caused the left rolling moment; the NTSB has revised the report accordingly."
Jacob Klinginsmith, Tamarack President, commented: “Tamarack is very pleased that the NTSB has decided to grant our Petition for Reconsideration concerning this 2018 accident and taken steps to correct multiple technical errors in the original investigation. This reversal shows the NTSB has the courage, professionalism, and proper process to make these corrections, and for that we applaud the NTSB. Our growing fleet of nearly 200 CitationJet customers see the safety, performance and fuel saving sustainability benefits of our technology on every flight. Our customers know that the Active Winglet upgrade is safe, reliable, and consistently brings a lot of value to Cessna CitationJets and other upgraded aircraft.”The revised Final Report is a response to the January 2022 Petition for Reconsideration submitted by Tamarack which cited multiple factual errors in the NTSB Final Report published in late 2021. The result of that report was a conclusion that could not be supported by the facts of that accident. Tamarack applauds the NTSB for studying the objective and verifiable facts and data available and using correct information to revise the probable cause.
