Witnesses Told NTSB Seaplane Spiraled Vertically Into Puget Sound


The NTSB says witnesses told investigators a turbine Otter seaplane operated by Friday Harbor Seaplane Tours spiraled vertically into Puget Sound on a scheduled flight from Friday Harbor to Renton, Washington. All 10 people onboard died. The NTSB released its preliminary report into the Sept. 4 accident in Mutiny Bay, north of Seattle, on Saturday. The NTSB said that after climbing slightly, the aircraft entered a vertical descent to the water.

“Several witnesses described the airplane as ‘spinning,’ ‘rotating,’ or ‘spiraling’ during portions of the steep descent,” the report says. Maintenance was up to date and plane had undergone a 100-hour inspection three days before the crash, in which a water rudder retract cable was replaced. In the previous inspection on Aug. 16, the NTSB says “the horizontal stabilizer hinge bolts, a right-hand engine ignitor, and a left-hand float locker latch were replaced.” The pilot had been flying the aircraft for five years and was properly certified. The wreckage has been located and will be raised with the help of the Navy.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

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  1. Any flight just after an “inspection” is a test flight.
    An inspection that touches both the rudder and the elevator is doubly so.

      • Maybe, maybe not. It also might take a few vibration cycles to work those hinge pins all the way free or that new cable finally binds up the rudder after a particularly bouncy takeoff. Like a newly overhauled engine, a plane fresh out of inspection can have all sorts of new issues.

        • Certainly the first flight after any maintenance should be performed as a test flight, but with the purpose of checking to make sure everything is working properly. If it does, you should be good to go.

          But I’m not sure what you’re suggesting should have been done.

          • When my flight controls and rigging were serviced, I really take my time on pre-flight for several flights.
            As far as “suggestions”, hopefully the final NTSB report will have some.

  2. Several similar accidents with this aircraft in Alaska, all involving loss of pitch control. Sometimes nose up, sometimes nose down. In each case, NTSB said “No recommendations”. Why?

    • Yeah, that theory came from that U-TUBE “expert” “Probable Cause” guy…What he failed to look at is the fact there are already AD’s and Service Bulletins that cover the trim tabs on those aircraft and perhaps the “real” accident investigators were smart enough to understand not every accident needs to have a safety recommendation. Remember, every “Safety Recommendation” has the potential to become a new or more restrictive FAR.

      • Maybe you’re right, maybe not.
        And existing AD’s and SB’s will not address a new age/hours-in-service related issue. Maybe the trim tabs are completely up to snuff. Is everything upstream of them good to go? If there is a new issue, it would be nice to know about it, doncha think? After all, nobody knew about the trim tab problem until they discovered it.
        Raising the wreckage should tell a lot.