Collision with water involving Cessna 208 Caravan, VH-WTY, Thomson Bay, Rottnest Island, Western Australia, on 7 January 2025

This preliminary report details factual information established in the investigation’s early evidence collection phase, and has been prepared to provide timely information to the industry and public. Preliminary reports contain no analysis or findings, which will be detailed in the investigation’s final report. The information contained in this preliminary report is released in accordance with section 25 of the Transport Safety Investigation Act 2003. 

The occurrence

On 7 January 2025 a Cessna 208 Caravan Amphibian (floatplane), registered VH-WTY and operated by Swan River Seaplanes, was being utilised for non-scheduled passenger air transport flights to and from South Perth and Rottnest Island, Western Australia. 

At about 0840, the pilot and 10 passengers prepared for the flight to Rottnest Island. Prior to boarding at South Perth, passengers watched a safety briefing video and were fitted with life jackets. At 0915 the aircraft departed, before climbing to a cruising altitude of about 1,600 ft. The aircraft orbited to the north of Rottnest Island, then landed in a south-south-west direction on the waters of Thomson Bay at 0926 (Figure 1). Passengers recalled that the flight was uneventful. The passengers alighted the aircraft onto a pontoon and were then conveyed to the island onboard a tender vessel. The aircraft remained at Thomson Bay throughout the day, with the pilot remaining on the island.

Figure 1: Map showing Rottnest Island and key locations in Thomson Bay (inset)

Source: Google Earth, annotated by the ATSB

At 1116, the chief pilot of Swan River Seaplanes sent the pilot a text message stating that winds were forecast to increase that afternoon, and included an image from a weather website, showing that winds at Rottnest Island were 25 kt with gusts to 34 kt.

The pilot responded that they may need to return to South Perth earlier than the planned 1600 departure time. The chief pilot indicated they agreed with this, stating that if necessary the passengers could return via ferry. The pilot responded to this text with a thumbs up.

CCTV recordings showed that at about 1305, the tender vessel used by Swan River Seaplanes to ferry passengers to and from the pontoon in Thomson Bay departed from alongside the aircraft. The video appeared to show the pilot travel north on the vessel from the pontoon. The vessel was then returned to shore where it was docked at a jetty on Rottnest Island at about 1320.

At about 1330, the pilot sent a text message to the chief pilot of Swan River Seaplanes, stating that the wind had reduced but the swell remained high at the normal departure location. The pilot stated they planned to depart taking a quartering crosswind closer to shore, where they perceived conditions were calmer. The chief pilot responded to this message stating they trusted the pilot’s judgement, encouraging the pilot to resist any perceived pressure to depart. Following this exchange, there was no further discussion around rescheduling the departure time.

At about 1500 the pilot requested the coxswain take them out in the tender vessel to the area normally used for floatplane departures from Thomson Bay to inspect the sea conditions. The coxswain recalled perceiving that conditions were rough, with swell about knee to waist high, and wind of at least 30 kt. The coxswain recalled that the pilot determined the conditions to be unsuitable for the planned departure, and requested to be taken closer to the southern shore of Thomson Bay. The coxswain recalled that conditions were calmer in this location, and the pilot had planned to depart on an easterly track towards Phillip Rock. 

At 1511, one of the directors of Swan River Seaplanes texted the pilot and asked about the wind conditions. The pilot responded that conditions were ‘ok but rough’, however the swell was ‘not too bad’ closer to shore. The pilot also noted in that text message conversation that the aircraft would be ‘pretty light’ for the departure. 

At about 1540, the passengers for the flight from Rottnest Island to South Perth were conveyed via the transfer vessel to the pontoon where the aircraft was moored. There were 6 passengers for the return flight, all of whom had travelled to Rottnest on the flight earlier that morning. Passengers described conditions onboard the vessel and pontoon as rough and windy. Each passenger was fitted with a life jacket before boarding the aircraft.

Once all passengers were boarded, the pilot signalled to the coxswain to release the mooring lines securing the aircraft to the pontoon. The aircraft then drifted before the pilot started the engine and taxied the aircraft to the south then north-west, before lining up for an easterly take‑off (Figure 2). At 1558, while taxiing the aircraft, the pilot was recorded making a broadcast on the Rottnest Island Common Traffic Advisory Frequency, announcing an intention to depart from Thomson Bay to the south-east.

Figure 2: VH-WTY take-off track with approximate location of key events 

Source: Google Earth, annotated by the ATSB

Flight data showed at 1600:20 engine power was applied for the take-off. Over the following 32 seconds, the aircraft travelled along the surface of the water in an easterly direction. Witness video and the fight data showed that at 1600:52,[1] as the aircraft approached the western tip of Phillip Rock it became airborne with a high nose attitude. At 1600:58, the aircraft rolled rapidly to the left with the left wingtip and then fuselage impacting the water. Further description of the aircraft behaviour during the take-off sequence is described in Recorded information. 

Survivors and other witnesses recalled the aircraft remained partially afloat in a perpendicular orientation, with the aircraft nose resting on the sea floor. The survivors reported that all cabin doors were submerged. The rear windows were not submerged. Four passengers moved into a pocket of air in the rear cabin and one of the passengers opened the top section of the rear right door. They and another passenger exited through this door. The coxswain of the tender vessel broke the rear left aircraft window, and 2 passengers recalled escaping through this broken window.

The pilot and the 2 other passengers remained in the aircraft, which later sank. Western Australia Police Force (WA Police) divers recovered the 3 deceased occupants in the evening of 7 January 2025.

Context

Pilot information

The pilot held a commercial pilot licence (aeroplane), with a current single-engine class rating and endorsements including for floatplane operations. The pilot had a current Class 1 medical certificate, with no restrictions.

The pilot had a total aeronautical experience of over 1,900 hours, including almost 1,400 hours on floatplanes and over 2,600 water landings. The pilot had about 700 hours experience in the Cessna 208 Caravan Amphibian, including over 60 hours accrued since commencing with Swan River Seaplanes in October 2024. Since commencing with the operator, the pilot had conducted 102 water landings, 12 of which were at Thomson Bay.

Aircraft information

VH-WTY (Figure 3) was a Cessna 208 Caravan Amphibian[2] floatplane, powered by a single Pratt & Whitney Canada (P&WC) PT6A-114A turboprop engine and a 3-bladed McCauley constant speed propeller. The aircraft was fitted with Wipline Model 8750 amphibious floats which enabled operation from both land and water. It was configured in a 13-seat interior layout. The aircraft was manufactured in the United States in June 2016, then registered in Australia in September 2016. It had accumulated about 1,125 hours total time in service at the time of the accident. Further aircraft information is detailed in VH-WTY maintenance history below.

The aircraft had 2 crew entry doors at the front of the cabin, next to the pilot (left) and copilot (right) seats. The crew entry doors had interior and external handles, which could be set to OPEN, CLOSE and LATCHED positions. The doors were also equipped with separate locks, and with lock override knobs inside the aircraft. To close the door, aircraft operating procedures instructed pilots to place the handle in the CLOSE position and pull the door closed, before rotating the handle to the LATCHED position. When unlocked and in the LATCHED position, the crew entry doors could be opened from either inside or outside the aircraft by rotating the handle to the OPEN position.

There were also 2 doors towards the rear of the cabin, each with a horizontal clamshell opening. Each rear door included separate handles for the upper and lower sections, and the upper section had to be opened first by pulling the handle inwards before rotating it from CLOSED to OPEN. When the lower section of the right rear door opened, a set of integral airstairs deployed.  Information about passenger use of these exits following the accident is described in Seating arrangement and occupant injuries below.

Figure 3: VH-WTY

Source: www.JetPhotos.com, Sebastian Sowa

Location information

Rottnest Island is located 18 km offshore the West Australian coast. The island has a sealed runway with 1,293 m available for the take-off run at Rottnest Island Airport. The runway is oriented east-west.

Thomson Bay is situated on the eastern side of Rottnest Island and is the main landing point for marine vessels visiting the island. Phillip Rock is a rocky outcrop about 400 m offshore the eastern tip of Thomson Bay.

The operator had received approval to conduct water landings and departures into and out of Thomson Bay. Swan River Seaplanes pilots reported that flights to Rottnest Island would normally utilise the sealed runway at the airport, and that Thompson Bay would only be utilised if forecast weather (wind direction and wind speed) would make the sealed runway unsuitable. The approval included a designated landing area, located in the south-eastern end of Thomson Bay, with the south-western area of the landing area subject to a 5 kt marine traffic limitation (Figure 4). Company pilots reported that it was normal practice to depart from Thomson Bay along a southerly track and to become airborne prior to the 5 kt limitation.

An initial review of flight data by the ATSB showed results consistent with these recollections. There were 6 flights which departed from Thomson Bay after Swan River Seaplanes commenced operations with VH-WTY on 2 January, comprising 3 flights on 4 January, 2 flights on 5 January, and the accident flight on 7 January. All these flights departed with a southerly track, except for the accident flight which departed with an easterly track (Figure 5). 

Figure 4: Thomson Bay approved floatplane landing area

Source: Google Earth and Rottnest Island Authority, annotated by the ATSB

Figure 5: Recorded departure tracks for VH-WTY within Thomson Bay displaying the difference between the accident flight and the previous flights

Source: Google Earth, annotated by the ATSB

Weather and sea conditions

The Bureau of Meteorology automated weather information service (AWIS) located at Rottnest Island Airport provided meteorological observations at one-minute intervals. At 1600, the AWIS reported winds of 25 kt from 210° (approximately south-south-westerly). The temperature was 24°C.

Witnesses to the accident recalled strong gusty winds in Thomson Bay throughout the afternoon of the accident. Video recordings taken on the afternoon of the accident showed that the sea was calm close to the southern shore of Thomson Bay. Further into the bay, however, waves were larger and more frequent. The sea state around the aircraft during the take-off run was choppy, with some white caps. Video showed that beyond the eastern end of Thomson Bay, sea conditions became significantly worse, with larger and more frequent white caps (Figure 6). 

Figure 6: Aerial view shortly after the accident near to the impact point showing the rougher sea state outside of Thomson Bay (top), with surface photography from a vessel in Thomson Bay (bottom left) and a witness on the shore (bottom right) showing conditions shortly before the accident. 

Note: The police video (top image) was captured at about 1627, approximately 26 minutes after the accident.

Source: Western Australia Police Force, ferry operator and witness video, modified by the ATSB

Site and wreckage information

Accident site information and wreckage recovery

Analysis of witness video and information recorded by avionics and navigational equipment onboard the aircraft showed that the aircraft collided with the sea approximately 70 m south-east of Phillip Rock. The right float and part of the left float separated from the aircraft after the collision, and these were later recovered by WA Police and members of the public. The rear section of the left float remained tethered to the aircraft by the fly wire and sea rudder control cables.

The aircraft drifted approximately 800 m north of Phillip Rock until being tethered to the sea floor by WA Police divers. Their dive video showed that the main body of the aircraft remained largely intact following the collision (Figure 7). On 9 January 2025, commercial salvors lifted and recovered the aircraft using barges and a crane (Figure 8), before it was transported to a secure storage facility near Perth for further examination. 

Figure 7: The aircraft sank inverted onto the sea floor within Thomson Bay 

Source: Western Australia Police Force

Figure 8: VH-WTY recovery from Thomson Bay

Source: ATSB

Wreckage examination

Examination of the aircraft wreckage at the secure facility identified:

• The wings, fuselage and floats did not display any physical markings that the aircraft had struck landmass or a submerged object prior to the collision with the sea.
• The engine controls were attached to the associated engine components and were free to move through their full range of movement. 
• The propeller blades were intact and attached to the propeller hub. They could be rotated through 360º about the feathering axis, indicating internal damage to the feathering mechanism. The investigation will include further analysis to determine the significance of this damage.  
• All 3 propeller blades were significantly bent toward the blade face. The significance of this was not able to be determined due to the propeller assembly resting on the sea floor prior to recovery.
• The primary flight controls could not be moved due to structural damage from the accident. The flight pushrods, bellcranks and control cable hardware were examined for continuity and correct assembly. No pre-existing damage or defects were identified. 
• The flap selector was in the ‘full’ position and the flap position indicator was showing an intermediate position of about 15°. The wing flaps were in the retracted position. 
• The instrument panel and combing appeared undamaged. All circuit breakers were pushed in except those corresponding to the strobe light and stall warning.
• The wings were swept back, with significant damage to both wings outboard of the ailerons. The left wing section, outboard of the aileron pushrods, was separated during the accident sequence and not recovered. 
• Video footage from WA Police divers for the recovery of the deceased occupants showed that the left (pilot) crew door was in the LATCHED position and the right crew door was in the LATCHED position. The upper section of the right rear door was open but the lower section, incorporating the airstairs, remained closed. Both sections of the left rear door were closed (with ATSB examination showing both handles in the CLOSED position).[3] The ATSB examined the functionality of all doors and determined that they could be unlatched and opened. Some doors were difficult to open, most likely due to structural damage to doorframes following the accident. 

Engine examination

• P&WC provided an engineering specialist to complete an internal borescope inspection of the engine. No evidence of pre-accident damage was identified.
• The engine was removed from the aircraft in preparation for detailed teardown examination at the P&WC facilities in Canada. The ATSB analysis will consider the report from that examination.

Recorded information

The ATSB recovered the Garmin G1000 avionics equipment from VH-WTY. Using the flight data recovered from the G1000, witness video recordings of the accident, and automatic dependent surveillance broadcast (ADS-B) data[4] the following was identified:

• Engine power was applied to commence the take-off at 1600:20, with the aircraft about 600 m from the western tip of Phillip Rock, and at a heading of 108°.
• Fifteen seconds into the take-off the aircraft had accelerated to 40 kt and was about 400 m from Phillip Rock. The aircraft transitioned onto the step[5] and the nose was lowered. The aircraft heading was manoeuvred on a course between Phillip Rock and the eastern tip of Thomson Bay. 
• About 200 m from Phillip Rock, and with a recorded airspeed of 46 kt, the aircraft appeared to cross a wave or swell. Video footage showed the aircraft appearing to bounce on the water, becoming airborne momentarily before settling back onto the water.
• Over the next few seconds, the left wing rose on 2 occasions as the aircraft approached Phillip Rock, with the left float separating from the water. On each occasion, the aircraft struck waves and the right float did not separate from the water.
• There was a gradual reduction in engine power for about 20 seconds, commencing prior to the aircraft becoming airborne. 
• About 30 m from Phillip Rock, the aircraft had accelerated to a recorded airspeed of 57 kt, and again appeared to strike waves. 
• At 1600:52, the aircraft then became airborne, with a nose high attitude and on a heading of about 110°. Over the next few seconds, the aircraft maintained a nose-up attitude of between about 15°–18°. The aircraft climbed to about 16 ft above the surface of the water. The right wing then dropped, followed by an apparent aerodynamic stall of the left wing, with the aircraft rolling to the left.
• A witness video recording at about the time the aircraft separated from the water showed that the flaps were extended for take-off. The video also indicated the water rudders were extended. 
• At 1600:56 the engine torque increased rapidly.
• At 1600:58 the left wingtip struck the water then followed by the fuselage. 

Seating arrangement and occupant injuries

Surviving passengers recalled watching a safety briefing video prior to boarding the flight to Rottnest Island on the morning of the accident, with the pilot providing an additional safety briefing in the aircraft prior to departing from South Perth. Passengers recalled that there was no briefing provided prior to the departure from Thomson Bay, with the pilot asking if the passengers recalled the briefing from the morning. Passengers reported that the safety video and pilot briefing were thorough and provided adequate information on the use of seatbelts and the location and use of the aircraft exits.

One passenger additionally recalled that during boarding the aircraft prior to the departure from Thomson Bay, the pilot requested the passenger assist with closing and latching the left rear door. The passenger considered that the pilot’s instructions for closing the door were crucial for the passenger to subsequently open the right door after the aircraft struck the water. 

The ATSB identified multiple safety information cards for the Cessna 208 Caravan in the aircraft wreckage, which showed information including the location of the aircraft exits, and how to unlatch and open the aircraft doors.  

Surviving passengers recalled wearing life jackets during the accident flight. The life jackets worn by passengers were designed for constant wear in a pouch, with a belt securing the pouch around the waist. The life jackets were designed to be donned and inflated when required in an emergency. The life jackets could be inflated using a gas-cylinder inflation system or using an oral inflation system. 

Surviving passengers recalled that the seating positions (Figure 9) for the accident flight were as follows:

• The pilot was seated in the normal position in the front left seat, and there was no passenger seated in the front right (copilot) seat.
• Two passengers were seated in the second row, with the central seat vacant. The passenger seated in the left seat was fatally injured in the accident. The passenger in the right seat recalled escaping through the rear left window, which had been broken by the coxswain of the operator’s tender vessel. 
• Two passengers were seated in the third row, with the central seat vacant. The passenger seated in the right seat was fatally injured in the accident. The passenger seated in the left seat was pulled from the aircraft through the left rear window by the coxswain of the operator’s tender vessel. 
• Two passengers were seated in the fourth row, with the central seat vacant. Both passengers in the fourth row survived the accident. The passenger seated in the left seat of the fourth row opened the top section of the right rear door, through which they exited the aircraft along with the passenger seated in the left seat of the fourth row. 

The investigation will consider the post-mortem examination reports for each of the fatally injured occupants, including in support of analysis of the accident survivability.  

Figure 9: Cessna 208 seating plan showing the occupant location for those who survived (green) and those who sustained fatal injuries (red)

Passengers were able to exit the aircraft using the top section of the right rear door (upper inset) and left rear window (lower inset).

Source: Textron Aviation, modified by the ATSB 

Swan River Seaplanes

Swan River Seaplanes conducted Part 135 of CASR air transport operations for the purpose of passenger flights from the Swan River to Rottnest Island and Margaret River, Western Australia. It also operated flights around Perth, Western Australia, departing and landing on the Swan River. The operator reported commencing flights to Rottnest Island in October 2017, with operations from Thomson Bay commencing in January 2023. 

Swan River Seaplanes had cross-hired VH-WTY, commencing passenger‑carrying flights in the aircraft on 2 January 2025. Swan River Seaplanes operated another Cessna 208, registered VH‑UOZ, however due to maintenance requirements this aircraft had been unavailable for operations since December 2024. 

Swan River Seaplanes had 3 line pilots including the chief pilot. Another pilot, who conducted check and training for the operator, had also previously conducted line flights but was not operating in that function at the time of the accident. 

VH-WTY maintenance history    

Maintenance documentation for VH-WTY showed that:

• The aircraft had been operated in the Whitsunday region of Queensland (Qld) since arrival into Australia. In the period between 29 June 2021 to 20 October 2023, it had not been operated and was inactive at Shute Harbour Airport, Qld. 
• It was then flown to Caloundra, Qld where it stayed for 31 days, and then flown to Sunshine Coast Airport, Qld where it remained for 37 days. It was not operated during these periods except for a relocation flight where it was flown to Bankstown Airport, New South Wales (NSW) on 3 March 2024.
• The aircraft had been inactive at Bankstown, NSW, from 4 March 2024 to 27 December 2024, with no recorded flights. Maintenance releases and logbooks did not show evidence of engine or airframe preservation having been performed for the periods of storage of the aircraft. 
• On 27 December 2024, a special flight permit was issued by an authorised approver on behalf of the Civil Aviation Safety Authority, for a ferry flight to Jandakot, Western Australia (WA). This permit was required due to the expiry of the maintenance release on 20 October 2024. 
• Maintenance documentation showed that a new battery was installed in the aircraft at Bankstown on 27 December 2024.
• On the morning of 28 December 2024, a 12-minute flight was recorded for the Bankstown Airport flying circuit.
• From 28 December to 29 December 2024, the aircraft was flown from Bankstown Airport, NSW to Jandakot Airport, WA.
• The aircraft and engine logbooks identified that from 30 December 2024 to 1 January 2025, the airframe, floats and role equipment (life jackets, fire extinguisher and first aid kit) were inspected. From the records, a new elevator pushrod bearing was installed, and new rudder pulleys were installed for the left and right floats. Engine work included a compressor power recovery wash and desalination rinse. Additionally, the chip detector plugs were recorded to have been inspected with no defects listed.

Further investigation

To date, the ATSB has conducted the following activities:

• interviewed Swan River Seaplanes personnel and survivors of the accident
• examined the aircraft wreckage
• reviewed information recorded by avionics equipment onboard VH-WTY
• reviewed the forecast and observed weather conditions at Rottnest Island
• reviewed video recordings from witnesses, CCTV and other sources.

The investigation is continuing and will include review and examination of:

• information recovered from mobile devices
• the recorded data from the aircraft engine 
• the results of the engine teardown by Pratt & Whitney Canada
• weather and sea conditions in Thomson Bay on the day of the accident
• the information available to the pilot for Thomson Bay operations on the day of the accident
• the operator’s procedures and other risk controls for assessing the suitability of planned floatplane departures from Thomson Bay
• the history, identification and assessment of Thomson Bay for floatplane operations
• the aircraft maintenance history 
• pilot training records, medical information and recent history
• pilot and passenger injuries and post-mortem reports
• the safety briefings provided to passengers, the location and availability of exits after the accident, and the performance of the aircraft seatbelts
• regulatory oversight and surveillance for the floatplane operations from Thomson Bay and for the maintenance of VH-WTY.

A final report will be released at the conclusion of the investigation. Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken. 

Acknowledgements

The ATSB acknowledges the support of the Western Australian Police Force and those involved with the recovery of VH-WTY.

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