Story ID: 
Tamarack Asks NTSB To Reconsider Probable Cause
By: Matt Thurber
Caption: Tamarack Aerospace is disputing many points in the NTSB's final report on the 2018 crash of a CitationJet equipped with Tamarack winglets.
Word Count: 244
Tamarack Aerospace has submitted a petition for reconsideration to the NTSB, asking it to reconsider the probable cause conclusion in the crash of a Cessna CitationJet on Nov. 30, 2018. The jet was equipped with Tamarack winglets and the Active Technology Load Alleviation System, which uses Tamarack Active Camber Surfaces to alleviate structural loads.

The NTSB’s probable cause was “the asymmetric deployment of the left wing load alleviation system for undetermined reasons, which resulted in an in-flight upset from which the pilot was not able to recover.”

Tamarack’s petition asked the NTSB “to reconsider and modify its findings and determination of probable cause…The basis of this petition is that the NTSB has made erroneous findings that are unsupported by the factual record, inconsistent with engineering principles, or proven to be physically impossible.”

According to Tamarack, the NTSB failed to consider the company's supplemental party submission sent to the Board four business days before issuance of the final report and 35 months after the accident. Another issue is “the report states that the autopilot prematurely disconnected at a 30-degree bank angle. The autopilot system disconnect threshold is 45 degrees, which is 15 degrees more than the bank angle at which the accident aircraft’s autopilot actually disconnected. Therefore, the autopilot clearly did not disconnect because of excessive bank angle.”

Parties to the investigation have 90 days to respond to the petition, after which the NTSB makes a decision.