The Northwest Seaplanes Accident on Mutiny Bay: A Few Preliminary Thoughts and Legal Considerations

Photo © Getty/Jacob Stark

The opinions stated in this article are those of the authors and not of the WSBA.

Behind every aviation disaster there are thousands of stories about life, love, relationships, human nature, and ultimately death and human failure. When a catastrophe strikes, the emotional impact and personal losses are unbearably significant for families and close friends of those who perish. 

On Sept. 4, 2022, a Northwest Seaplanes De Havilland DHC-3 Otter, N725TH, crashed into Mutiny Bay, located off the southwest coast of Whidbey Island, killing all 10 persons on board, including a child and Gabrielle Hanna, a member of the Washington State Bar Association. The flight was a scheduled air carrier seaplane flight from Friday Harbor to Renton’s Will Rogers-Wiley Seaplane Base, located on the south end of Lake Washington.

As the passage of time begins to soften the shock and significant impact of the accident, the search for answers begins. Given that the investigation into this accident is ongoing and many relevant facts are not known, this article addresses some of the factual and legal issues that may arise in the aftermath of this accident—including investigation into the cause of the accident, owner/operator determination, and potential probate issues.

Gabrielle “Gabby” Hanna was a 29-year-old attorney and WSBA member from Seattle. She was a graduate of the University of Washington School of Law and an associate in the Seattle office of Cooley LLP, an international law firm. Hanna loved traveling, hiking, and cooking elaborate meals. Read more about Hanna here: 


Eighteen minutes after taking off from Friday Harbor in route to Renton, N725TH started to climb, from 800 feet to 1,175 feet when, according to witnesses,11 it suddenly and inexplicably dropped and rapidly descended nose-first into the Puget Sound waters below. There were no radio transmissions or other indications of what went wrong. Little is currently known about what caused the accident, and its wreckage is spread 190 feet below the surface of the water. 

On Sept. 16, the National Transportation Safety Board (NTSB) issued its preliminary accident report,22 Id. which provides general flight, route, weather, and pilot information. N725TH did not have any voice or data recording capability; passenger phones, if located, may provide important video, audio, and photo information. The preliminary report states that recent maintenance was performed on the aircraft on Aug. 16 and on Sept. 1, four days before the accident. Pursuant to FAA-issued Airworthiness Directives (ADs), which are mandatory regulatory maintenance requirements, regular inspections were required of the elevator control tabs, which assist in controlling the nose-up-and-down pitch of the aircraft; these inspections were apparently performed. In addition, the horizontal stabilizer hinge bolts (also related to pitch control) were replaced. 

Since very little wreckage floated to the surface, it is presumed that there are hundreds of small wreckage pieces spread throughout the accident area due to the currents of Puget Sound waters. The NTSB has located and retrieved the main wreckage, with the assistance of the U.S. Navy’s underwater wreckage recovery Deep Drone 8000. While it is not known how much of the wreckage has been recovered, there is little doubt that NTSB experts will be challenged putting together the causation puzzle, especially if significant pieces of the wreckage are not recovered. 

The NTSB may take up to 24 months to issue factual and probable cause reports in aviation accidents; during this time potential litigants will independently investigate the accident using their own aviation experts and engineers. (Litigants cannot use NTSB reports in civil litigation, as these reports are inadmissible under federal law.33 49 U.S.C. §1154(b).)

In aircraft accidents where wreckage evidence is sparse (burned, broken, lost, or destroyed), experts focus their attention on what remains, such as maintenance records and the aircraft operating history. They also research similar accidents involving the same type of aircraft as potentially relevant to causation.


The DHC-3 Otter, N725TH, involved in the Sept. 4 accident was manufactured in 1967 by De Havilland Aircraft of Canada.44 From 1951 to 1967 more than 400 Otters were manufactured. Thus, there is a significant operating (and accident) history available for analysis. The NTSB has investigated 37 accidents involving DHC-3 Otter aircraft. The Canadian Transportation Safety Board (TSB) investigated an additional 15 accidents. As a result of certain accidents, both the TSB and NTSB have issued numerous Airworthiness Directives (ADs).55 14 C.F.R. Ch. 39. In determining whether N725TH may have experienced a catastrophic loss of controlled flight (a situation in which a pilot is no longer able to control the aircraft while in flight) on Sept. 4, investigators will likely look at reports of other DHC-3 loss of flight control accidents, some of which are summarized in the following list.

  • On June 20, 1989, DHC-3 Otter N41755 unexpectedly pitched nose-down when the horizontal stabilizer jackscrew failed in flight.66 NTSB Final Report Accident No. ANC89IA099, The cause was determined to be improper lubrication and excessive wear. Notably, this event was similar to the cause of the Alaska Airlines Flight 261 crash on Jan. 31, 2000, where the jackscrew also failed due to poor maintenance and inspection practices.
  • On Feb 4, 1992, DHC-3 Otter N13GA unexpectedly pitched nose-down in cruise flight when the aircraft’s left elevator trim servo aft rivets tore out. Failures of the trim servo have been reported in other accidents.77 NTSB Final Report Accident No. ANC92LA032,
  • On July 13, 1995, DHC-3 Otter N472PM experienced a significant vibration after take-off. Inspection upon landing indicated that the elevator trim servo had cracked and partially separated.88 NTSB Final Report Accident No. ANC95LA103,
  • On May 9, 1996, the right wing of Canadian-registered Otter C-GBTU separated from the aircraft while on approach to a water landing.99 TSB Aviation Investigation Report A96P0082, The Otter’s right wing lift strut had failed due to a fatigue crack that had developed through one of the strut’s mounting bolt holes. Both Transport Canada and the FAA issued ADs mandating a heightened inspection schedule of the Otter’s lift struts. 
  • On Dec. 28, 2002, DHC-3 Otter N3904 experienced a loss of rudder control after one elevator partially came off its hinges and blocked the movement of the rudder. The elevator torque tube that connects both elevators showed signs of improper replacement.1010 NTSB Final Report Accident No. ANC03LA021,
  • On March 31, 2011, Canadian-registered Otter C-GMCW experienced a catastrophic in-flight break-up. No specific determination was possible as to the ultimate cause, but the TSB did determine that the break-up was the result of an overspeed condition after the aircraft diverged from straight and level flight for an unknown reason.1111 TSB Aviation Investigation Report A11W0048,
  • On May 30, 2014, DHC-3 Otter N3125N unexpectedly pitched nose-down in cruise flight when the aircraft’s left elevator trim tab separated. The aircraft trim tab had been modified, ostensibly to prevent flutter, which is a catastrophic condition where flight surfaces vibrate, potentially to the point of failure. A safety issue was created by the installation of the more powerful turbine engines in the Otter. Apparently, the prop wash from the turbine engines resulted in increased airflow over the control surfaces beyond the original design parameters. This increased airflow resulted in trim servo flutter and ultimately servo failure.1212 NTSB Final Report Accident No. ANC14LA035,
  • On Oct. 26, 2019, a DHC-3 seaplane crashed in Manitoba after its right wing came off during approach to land, causing the aircraft to dive nose-first into the lake, killing the three occupants. The TSB found a fatigue crack in the lift strut of the right wing caused the strut to fail, allowing the wing to come off. It also found that the maintenance inspection manual did not cover the area of these cracks.1313 TSB Aviation Investigation Report A19C0138,

In 2004, the FAA issued AD 2004–05–01 to address the modified trim tabs installed on turbine-engine-equipped Otters. In 2011, due to the continuing flutter issue in turbine Otters, the FAA issued AD 2011–12–02, which reduced the maximum allowable airspeed for these aircraft down to 134 mph for float-equipped aircraft. The safety issue arose when the type certificate holder (the FAA-authorized manufacturer) modified the original design of the trim servo but failed to determine if that modification was safe vis-a-vis the original design.1414

As noted in the preliminary Mutiny Bay accident report, there is another AD, 2011-18-11, that requires repetitive inspections of the elevator control tab. The AD notes that this would prevent excessive elevator free play, which “could lead to loss of tab control linkage and severe flutter,” causing “possible loss of control.”1515 (search 2011-18-11).

The problems with the Otter trim tab system in turbine-equipped Otters is an area that NTSB and private investigators will likely focus on as they try to determine the cause of the Northwest Seaplanes N175TH accident. 


After an accident the determination of who the FAA-certified operator is can sometimes be challenging. The Federal Aviation Regulations (FARs)1616 14 C.F.R. et seq. require certain types of air carriers to obtain Part 135 certificates, which are issued after extensive FAA review and approval. Washington company West Isle Air, Inc. is listed as the FAA-certified Part 135 operator for the aircraft involved in the Mutiny Bay accident, N725TH,1717 and thus appears to be the legal operator of N725TH at the time of the accident. (The NTSB preliminary report does not identify the Part 135 operator, instead leaving the lines “Operator” and “Operator Designation Code” blank.) However, “doing business as” (dba) names may also be used, but only if such names are listed on the certificate holder’s operations specifications.1818 14 CFR §119.9.


The flight data from the accident flight of N725TH reflects a relatively low cruising altitude of approximately 600 to 800 feet immediately prior to the accident. This raises the question of why a pilot would have chosen to operate a seaplane at this altitude.

The answer is multi-faceted. First, the airspace surrounding the flight corridor from Seattle to the San Juan Islands, though the Gulf Islands and up the Inside Passage, is surrounded by active airports such as Paine Field in Everett, Naval Air Station Whidbey Island, Victoria International Airport, Bellingham International Airport, and, further north, Vancouver International Airport. Smaller airports are also spread throughout this area, both on the islands and on the coastal mainland. Thus, in order to avoid the busier air traffic around airports, and to avoid required air traffic control clearances through busy areas, flying low and below certain classes of airspace can be a more efficient and safer alternative.

Second, since the more populous land aircraft need to fly at higher altitudes over water (so that they can glide to shore in the event of engine failure), seaplanes are not so restricted because in an emergency they can land on water. Thus, there should be less air traffic at lower altitudes over water than higher up. Third, weather and lower ceilings may still allow seaplanes to safely fly their routes at a lower altitude while remaining clear of clouds. Fourth, winds may be more favorable at lower altitudes, which reduces flight time and fuel consumption. Fifth, of course, is that the experience for seaplane passengers is enhanced by flying closer to the beautiful scenery below.

The FARs establish standards for minimum altitudes for aircraft, when not taking off or landing. N175TH was operating under Part 135, which is more restrictive because the operator is an conducting air taxi/commercial operation for paying passengers. The daytime minimum flight altitude for airplanes when operating visually (not in clouds) is generally 500 feet above the surface.1919 14 C.F.R. §135.203(a)(1). 

While flying at lower altitudes may still comply with the regulations, from the early stages of pilot flight training, pilots are taught that altitude translates into time when faced with an emergency, especially one involving loss of engine power. The more altitude below means the more time there is to troubleshoot potential problems, recover from unusual altitudes, and to implement emergency procedures. In the case of the Sept. 4 Mutiny Bay accident, however, if it is determined that there was a catastrophic flight control failure, more altitude would not have made a difference. 


Determining who recovers under wills or intestate statutes often presents probate counsel with unique challenges in aviation accident cases, depending on the circumstances. Likewise aviation counsel handling wrongful death claims may face numerous challenges related to personal representatives, beneficiaries, and recoverable damages. 

A family of three died in the Mutiny Bay accident, plus their unborn child. Another married couple died, leaving behind children. These simultaneous deaths of members of the same family raise the question of application of the Uniform Simultaneous Death Act. Washington’s Act2020 RCW Ch. 11.05A. provides, in relevant part, “an individual who is not established by clear and convincing evidence to have survived the other individual by one hundred twenty hours is deemed to have predeceased the other individual.”2121 RCW §11.05A.020. The Act is not to be applied if its application results in the state taking by way of intestacy; however, the interplay can be tricky if there is no otherwise controlling will provision that would trump the Act.2222 RCW §11.05A.060.

Other aspects may become challenging as well, including the death of a fetus, which if viable has been recognized in Washington as giving the parents a wrongful death cause of action.2323 Baum v. Burrington, 119 Wn. App. 36, 79 P.3d 456 (Div. 1, 2003) (parents have a wrongful death claim for the death of a viable fetus under Washington wrongful death law, but recovery is not available for death of an unviable fetus). But if both parents also die in the accident, the 2019 changes to Washington’s wrongful death and survival statutes may apply, allowing both wrongful death and survival claims as long as there is at least one surviving sibling.2424 RCW §§4.20.020, 4.20.046, and 4.20.060 (2019).

With the exception of parents who lose a child, Washington law requires family claims to be brought through a personal representative. In such cases, the better course may be appointment of a personal representative who is not a beneficiary of the wrongful death/survivor claims, as the appointment can be for the limited purpose of pursing such claims.


Seaplanes are an anchored part of Pacific Northwest history. With their mid-20th-century vintage, these old birds connect us to the past while continuing to fly passengers and cargo throughout northwest Washington and southwest British Columbia today. They are thrilling to see and hear in the skies above and on local waters, and are exhilarating to ride in. Yet, as so recently seen, tragedy may strike when least expected. 

After this article went to press, on Oct. 4, 2022, the FAA issued Emergency Air Worthiness Directive (AD) 2022-21-51 to owners and operators of Model DHC-3 seaplanes, the same type of plane involved in the Mutiny Bay accident. The AD states that it was “prompted by multiple recent reports of cracks in the left-hand elevator auxiliary spar,” and requires “repetitive detailed visual inspections of the entire left-hand elevator auxiliary spar for cracks, corrosion, and previous repairs …” According to the FAA, the AD was issued because it determined that “an unsafe condition is likely to exist or develop in other products of the same type design.”

About the authors
About the authors

The authors are all attorneys with Aviation Law Group PS ( in Seattle, where they exclusively practice aviation accident law on behalf of victims and their families. At the time of this publication, Aviation Law Group PS had commenced its own investigation into the Northwest Seaplanes accident.

Robert Hedrick (pictured) is also a commercial pilot, seaplane pilot, FAA-certified aviation mechanic, and has an LL.M. in International Aviation Law. 
Casey DuBose is a commercial pilot and flight instructor. 
Kerry Kovarik is a commercial pilot and FAA-certified aviation mechanic with inspection authority. 
Chris Rusing is an airline pilot (captain, Airbus 320) and flight instructor. 

At some time during the last 20 years, DuBose, Kovarik, and Rusing were all law students in Hedrick’s aviation accident law course, which he still teaches at Seattle University School of Law. 



2. Id.

3. 49 U.S.C. §1154(b).


5. 14 C.F.R. Ch. 39.

6. NTSB Final Report Accident No. ANC89IA099,

7. NTSB Final Report Accident No. ANC92LA032,

8. NTSB Final Report Accident No. ANC95LA103,

9. TSB Aviation Investigation Report A96P0082,

10. NTSB Final Report Accident No. ANC03LA021,

11. TSB Aviation Investigation Report A11W0048,

12. NTSB Final Report Accident No. ANC14LA035,

13. TSB Aviation Investigation Report A19C0138,


15. (search 2011-18-11).

16. 14 C.F.R. et seq.


18. 14 CFR §119.9.

19. 14 C.F.R. §135.203(a)(1). 

20. RCW Ch. 11.05A. 

21. RCW §11.05A.020.

22. RCW §11.05A.060.

23. Baum v. Burrington, 119 Wn. App. 36, 79 P.3d 456 (Div. 1, 2003) (parents have a wrongful death claim for the death of a viable fetus under Washington wrongful death law, but recovery is not available for death of an unviable fetus).

24. RCW §§4.20.020, 4.20.046, and 4.20.060 (2019).