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 04.09.2022/
about 15:09 LT
Mutiny Bay near Freeland, WA - USA
Final Report
On September 4, 2022, about 1509 Pacific
daylight time, a float-equipped de Havilland DHC-3 (Otter),
N725TH, was destroyed when it impacted the water in Mutiny Bay,
near Freeland, Washington, and sank. The
pilot and nine passengers were fatally injured. The
airplane was owned by Northwest Seaplanes, Inc., and operated as a Title
14 Code of Federal Regulations (CFR) Part 135 scheduled passenger flight
by West Isle Air dba Friday Harbor Seaplanes. The flight originated at
Friday Harbor Seaplane Base (W33), Friday Harbor, Washington, with an
intended destination of Will Rogers Wiley Post Memorial Seaplane Base
(W36), Renton, Washington. Visual meteorological conditions prevailed at
the time of the accident.
The accident pilot was scheduled to fly the accident airplane on three
multipleleg roundtrips on the day of the accident. The first roundtrip
flight was uneventful; it departed from W36 about 0930, made four stops,
and returned about 1215.
The accident occurred during the pilot’s second trip of the day. A
review of recorded automatic dependent surveillance–broadcast (ADS-B)
data revealed that the second roundtrip departed W36 about 1253 and
arrived at Lopez Seaplane Base, (W81), Lopez Island, Washington, about
1328.
The data showed that the flight then departed
W81 and landed at Roche Harbor Seaplane Base (W39) about 1356. The
airplane departed W39 about 1432, arrived at W33 about 1438, and
departed about 1450.
According to ADS-B data, after the airplane departed W33, it flew a
southerly heading before turning south-southeast. The en route altitude
was between 600 and 1,000 ft above mean sea level (msl), and the
groundspeed was between 115 and 135 knots. At 1508:40, the altitude was
1,000 ft msl, and the groundspeed had decreased to 111 knots. Based on
performance calculations, at 1508:43, the airplane pitched up about 8°
and then abruptly pitched down about 58°. The data ended at 1508:51,
when the airplane’s altitude was 600 ft msl and the estimated descent
rate was more than 9,500 ft per minute.
Witnesses near the accident site reported, and security camera video
confirmed, the airplane was in level flight before it entered a slight
climb and then
pitched down. One witness described the descent as “near vertical” and
estimated the airplane was in an 85° nose-down attitude before impact
with the water. Several witnesses described the airplane as “spinning,”
“rotating,” or “spiraling” during portions of the steep descent. One
witness reported hearing the engine/propeller and noted that he did not
hear any “pitch change” in the sounds. The airplane continued in a
nose-low, near-vertical descent until it impacted water in Mutiny Bay.
Probable Cause
The National Transportation Safety Board determines that the probable
cause of this accident was the in-flight unthreading of the clamp nut
from the horizontal stabilizer trim actuator barrel due to a missing
lock ring, which resulted in the horizontal stabilizer moving to an
extreme trailing-edge-down position rendering the airplane’s pitch
uncontrollable.
Victims identified in seaplane crash
near Whidbey Island:
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Jason Winters (pilot)
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Patricia Hicks
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Sandra Williams
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Lauren Hilty
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Remy Mickel (minor)
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Ross Mickel
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Luke Ludwig
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Rebecca Ludwig
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Joanne Mera
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Gabrielle Hanna
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