The Lingering Mystery of 'Undetermined Reasons'

When an accident’s cause is not easily found.

Peter Garrison

Tuesday, February 18, 2020 at 06:02 PM ET

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A Rutan VeriEze similar to the subject aircraft. Wikimedia

Key Takeaways:

The article uses a 2007 VariEze crash to illustrate the NTSB's "loss of control for undetermined reasons" finding, emphasizing the true mystery behind such accidents.
Initial investigation focused on the aircraft's airbrake due to a past incident, but experts and the author dismissed it as an unlikely cause.
The author hypothesizes a sudden mechanical failure in the primary pitch control system, such as a loosened bolt, as a more plausible explanation for the pilot's panicked distress call and loss of control.
Despite speculation, the crash's cause remains officially undetermined due to the catastrophic disintegration of the aircraft and what the author implies was an incomplete investigation into the VariEze's unique flight control linkages.

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When the National Transportation Safety Board announces the probable cause of an accident, it often makes use of certain stock phrases. One of the most common is: “loss of control for undetermined reasons.”

Unlike “controlled flight into terrain,” which can often be traced to an incorrectly selected radio frequency or a sectional chart left behind, loss of control for undetermined reasons remains mysterious. These are not the loss-of-control accidents that result from icing encounters or from a non-instrument-rated pilot flying into IMC; in those cases, reasons can at least be plausibly guessed. Undetermined reasons really are undetermined.