On August 4, 2005, approximately 1745 Pacific daylight time, a Cessna 150M high-wing airplane, N66234, registered to the Subsonics Flying Club, Renton, Washington, and a deHavilland DHC-2 Beaver high-wing float equipped airplane, N741DB, registered to Associated Leasing LLC, of Edmonds, Washington, and operated by Sound Flight Inc., Renton, Washington, collided in flight approximately one and one-half miles northeast of the Renton Municipal Airport (RNT), Renton, Washington. The Cessna 150M was destroyed following an uncontrolled descent and impact with a vacant building. The DHC-2 Beaver sustained substantial damage and subsequently made an emergency landing on the grass median west of Runway 33 at RNT. The certified flight instructor and student pilot aboard the Cessna 150M sustained fatal injuries. The airline transport pilot and four passengers aboard the DHC-2 Beaver were not injured. The Cessna 150M was operated in accordance with 14 CFR Part 91, having departed RNT at an unspecified time on an instructional flight, and a flight plan was not filed. The DHC-2 Beaver was operated in accordance with 14 CFR Part 135 on a visual flight rules flight plan. The flight departed Barkley Sound, British Columbia, Canada, at 1623, and its destination was RNT.

At 1741:57, the pilot of the Cessna 150M (N66234) transmitted to the RNT controller, "Renton Tower, Cessna 234 incoming on to the I-90 bridge ah ah incoming on [ATIS information] Bravo." After the controller radar identified the target on the STARS3 [Standard Terminal Area Radar System], he instructed the pilot to "…enter a right downwind uh via the forty five report three miles northeast…," then requested the type landing.

At 1742:31, the pilot of the Cessna 150M advised that he would be conducting a full stop landing and was entering the downwind. Five seconds later, the controller advised, "…traffic ahead and to your right, one thousand six hundred [feet] turning southbound type unknown." The pilot did not respond. Radar data indicates that at this time the Cessna 150M was oriented to the left of the accident DHC-2 Beaver, rather than ahead and to its right as advised by the controller. (Refer to attached Radar Data)

At 1742:48, the pilot of another DHC-2 Beaver (N715JR) said, "…East channel I-90 bridge with [ATIS] Bravo for Washington One, low approach." The controller responded, "…traffic ah passing behind you now, 1300 [feet], a Cessna, no factor. Enter right downwind runway 33 correction via 405 report uh 3 miles north." The pilot acknowledged.

At 1743:13, the pilot of the accident DHC-2 Beaver (N741DB) transmitted, "…we've got information [ATIS] Bravo just northeast channel bridge inbound landing." The tower controller responded, "okay aircraft at the east correction northwest east channel bridge you have traffic twelve o'clock, two miles, Cessna, one thousand three hundred [feet] southbound." The pilot advised that he was looking for the traffic.

At 1743:37, after the tower controller confirmed the aircraft's call sign, he instructed the pilot of the accident DHC-2 Beaver (N741DB) to "…enter downwind via the 45 uh you'll be following that Cessna ahead and to your right." The pilot stated, "ok, uh, we'll be landing on the water." The controller said, "roger that he's landing on the hard surface you'll be doing a low approach over the water, understand."

At 1744:24, the tower controller said, "Beaver, correction floatplane one delta bravo confirm you have the Cessna in sight."

At 1744:29, the pilot of the accident DHC-2 Beaver (N741DB) reported, "ah we've got an aircraft on downwind ahead of us in sight."

At 1744:32, the tower controller said, "roger, you're following that aircraft." The pilot of the accident DHC-2 Beaver (N741DB) acknowledged the transmission.

At 1744:37, the pilot of the other DHC-2 Beaver (N715JR) reported entering the downwind. Five seconds later, the controller asked the pilot if he planned to land on the water or the hard surface. The pilot of the other DHC-2 Beaver advised that he would be landing on the water and "a midfield base would be great..." The controller then approved a midfield base and cleared the flight for a low approach.

At 1745:09, the tower controller instructed the pilot of the Cessna 150M to "proceed direct to the downwind." The pilot acknowledged.

At 1745:14, the tower controller advised the Cessna 150M, "and you have traffic off your right wing, has you in sight, one thousand six hundred [feet], floatplane." The pilot advised he had "the traffic in sight..."

At 1745:46, the controller confirmed that the accident DHC-2 Beaver would be landing in the water and the pilot replied, "affirmative. We have the aircraft on base." According to the pilot's statement, he wrote, "I observed the Beaver ahead to begin his midfield base turn and began to slow the aircraft in preparation for following him and landing on the water."

At 1745:53, the controller said, " you have the traffic that's passing underneath you still?"

At 1745:56, the pilot of the accident DHC-2 Beaver stated, "ah yah base to final landing on the water (unintelligible)."

At 1746:06, the pilot of the accident DHC-2 Beaver said, "Mayday, mayday uh Delta Bravo just had a midair."

The pilot of the accident DHC-2 Beaver continued inbound to RNT, and after assessing the damage to his aircraft landed on the grass median left of runway 33.

See the NTSB Air Traffic Control Group Chairman's Factual Report in the public docket for further details concerning air traffic control.

In an interview with the NTSB investigator-in-charge (IIC), and according to the Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1), the pilot of N741DB, the DHC-2 Beaver, reported that while outside of Class D airspace and monitoring the RNT control tower frequency, he observed another DHC-2 Beaver (N715JR) ahead of him. The pilot stated, "I heard his transmission and intended on following that Beaver to over fly the midpoint of Runway 33 for our base to land northbound on Lake Washington." The pilot further stated that air traffic control (ATC) activity was fairly high and that there was at least one double transmission or blocked transmission. The pilot reported that after making contact with ATC he informed the tower that he had the traffic ahead on downwind in sight and was told to follow him. "I was given [a] traffic advisory that I had traffic ahead of me, to which I again acknowledged that I had the Beaver traffic ahead of me on downwind in sight." The pilot stated that he observed the Beaver begin his midfield base turn and began to slow [his] aircraft in preparation for following him and landing on the water. "From my peripheral view to the left to low and behind I noticed the top of a high wing aircraft with white wings and a red wing tip just prior to contact.....I heard the sound of a heavy 'thud', followed by the violent yawing and rolling of the aircraft to the left." The pilot reported that he immediately notified the tower of the condition and declared an emergency, subsequently landing on the grass median to the left of Runway 33. The pilot further reported that after having descended to traffic pattern altitude, he still had visual contact on the Beaver on downwind. The pilot stated that he did not recall being advised of any other traffic in the area, and that he did not recall being advised of any Cessna traffic.

Several witnesses to the accident submitted written statements to the IIC. One witness reported that the Cessna's right wing tip made contact with the Beaver's right float, and that it appeared the Cessna was trying to miss the Beaver just before impact. Another witness said that just prior to impact both airplanes were in straight and level flight. All of the witnesses stated that after impact the Cessna nosed down steeply before impacting the vacant school building.

Representatives from the NTSB and the Federal Aviation Administration (FAA) responded to the Cessna 150M accident site, as well as to the location at RNT where the DHC-2 Beaver came to rest. Documentation was completed at each site. Both aircraft were subsequently removed to a secure location for further examination by representatives from the NTSB, the FAA, and parties to the investigation.


The certified flight instructor of the Cessna 150M was issued a flight instructor certificate on April 9, 2004. He also held a commercial pilot certificate with single-engine land, multiengine land, and instrument (airplane) ratings. According to the pilot's personal logbook, he had accumulated a total flight time of 510.7 hours, 274.6 hours in the accident make and model airplane, and 56.9 hours flight time as an instructor in the Cessna 150 aircraft. The flight instructor held a first class medical certificate, dated June 28, 2005, with the limitation that he shall wear corrective lenses.

The student pilot in the Cessna 150M had accumulated a total of 2.1 hours of total flight time prior to the accident flight, all dual instruction. The student pilot possessed a third class medical certificate that was issued on June 27, 2005. The medical certificate contained the limitation which stated that the pilot shall wear corrective lenses.

The pilot of the deHavilland DHC-2 Beaver held an airline transport pilot certificate for airplane single-engine sea and airplane multiengine land airplanes, a commercial pilot certificate for single-engine land airplane, and a private pilot certificate for gliders. The pilot also possessed a flight instructor certificate with airplane single-engine, airplane multiengine, and instrument ratings, an advanced and instrument ground instructor certificate, and an aircraft dispatcher's certificate. The pilot was also a licensed airframe and powerplant mechanic. The pilot reported a total flight time of 23,000 hours, 4,500 hours in single-engine airplanes, 300 hours in the accident airplane make and model, with 50 hours as an instructor in make and model. The pilot reported that he had flown 60 hours in the preceding 90 days, 27 hours in the last 30 days, and 6 hours in the last 24 hours. The pilot's last flight review, as required by 14 CFR Part 61.56, was satisfied on June 7, 2005, after the successful completion of his 14 CFR Part 135 checkride. He held a first class medical certificate issued on January 17, 2005, with the stated limitation that he shall wear corrective lenses.


The Cessna 150M, serial number 15075939, was a single-engine, high-wing airplane, equipped with a fixed tricycle landing gear, electrically actuated wing flaps, and was powered by a single reciprocating engine. The fuselage and empennage were of an all-metal semimonocoque design. The wings were externally braced and had two metal fuel tanks. The airplane was equipped with dual controls and two cockpit seats.

The aircraft was painted predominantly white. A red stripe ran the length of the fuselage on both sides of the airplane, bordered by a thin yellow stripe on the top and the bottom; the top yellow strip only extended from the nose of the airplane to just aft of the rear of the cabin door. The top of all three landing gear wheel pants were painted red, bordered on the bottom by a thin yellow stripe. Both of the airplane's wing tips were also painted red.

The airplane was issued a Standard Airworthiness Certificate on August 8, 1974, and was certified as a utility category airplane. The airplane had accumulated a total flight time of 6,128.4 hours since new. On November 11, 2004, the engine and airframe underwent their most recent annual inspections, with a total time of 6,102.4 hours. The engine was a 100 horsepower Teledyne Continental Motors O-200(48), serial number 265457-R. At the time of the accident, the engine had accumulated a total of 6,128.4 hours, with 25.4 hours since its most recent overhaul. On January 7, 2005, with a total time of 6,103.0 hours, the engine was removed for overhaul. It was reinstalled after the overhaul on April 4, 2005.

The 1958 de Havilland DHC-2 Beaver, serial number 1311, was a single-engine, high-wing, float equipped airplane, certified in the normal category. At the time of the accident, the airplane had accumulated a total airframe time of 6,869.5 hours, with 41.6 hours since its last inspection. At the time of its most recent major overhaul on July 14, 2005, the airplane's Pratt & Whitney R-985 engine had accumulated a total of 4,911.6 hours.

The paint scheme of the Beaver consisted of dark green, light gray, and white. Both sides of the aircraft's fuselage at mid level were painted with a gray stripe, bordered by a thin stripe of dark green on the top. The bottom area of the fuselage, extending the length of the airplane, the leading edges of both wings and each wing tip, as well as the top of the engine cowling, was also painted dark green. The remainder of the airplane was painted white.


At 1753, the RNT Automated Surface Observing System (ASOS), located approximately one and one-half nautical miles southwest of the collision point of the two aircraft, reported wind 330 degrees at 9 knots, visibility 10 statute miles, sky clear, temperature 30 degrees Celsius, dew point 10 degrees Celsius, and an altimeter setting of 29.98 inches of Mercury.


The main wreckage of the Cessna 150M came to rest on the second floor of an abandoned elementary school, in a near vertical nose down attitude, at coordinates 47 degrees 30.979 minutes north latitude and 122 degrees 11.791 minutes west longitude.

Examination of the accident site of the Cessna was conducted by a Senior National Transportation Safety Board air safety investigator and a Federal Aviation Administration airworthiness supervisor. The examination revealed that all components necessary to sustain flight were present at the accident site or in close proximity to the wreckage. It was reported that the top left elevator had straight tar scratches, the left wing had one straight scratch forward of the [left] flap inboard on top of the wing, and that the flaps appeared to be up. The NTSB investigator reported that he observed a fairly straight indentation slash mark on the roof to the southwest, with green and red Plexiglas on the northwest end of the mark. The slash mark was approximately 33 feet in length. The NTSB investigator further reported that from the hole in the roof, approximately 90 feet perpendicular and oriented in a southwest direction, were additional pieces of green Plexiglas. The FAA inspector reported that an elevator balance weight was located approximately 500 feet east of the accident site.

Due to the location of the accident site and the precarious position of the Cessna 150M wreckage, a more detailed examination of the aircraft was delayed until it could be recovered to a secured site.

On October 19, 2005, a layout examination of the Cessna 150M was conducted at the facilities of AV-Tech Service, LLC, Maple Valley, Washington. Assisting the IIC were a Senior NTSB aircraft accident investigator and representatives from the FAA, Teledyne Continental Motors, and Cessna Aircraft Company.

Damage to the airplane's empennage included the right horizontal stabilizer was bent and twisted, and separated from the fuselage, with its leading edge bent aft. The right elevator was separated from the fuselage and the trim tab remained attached. The left horizontal stabilizer remained attached to the fuselage, but its leading edge was bent aft. The left elevator was wrinkled, but remained attached to the fuselage. The airplane's rudder was bent and twisted, but remained attached to the empennage and the vertical stabilizer. The vertical stabilizer remained attached to the empennage, with the upper half of the stabilizer separated from the lower half. The aft fuselage body, measured at 9 feet 7 inches, was separated from the aft cabin area. The airplane's left landing gear remained attached to the fuselage, while the right landing gear was separated.

Control cable continuity could not be established due to salvage recovery operations. Numerous tension overload failures were observed.

The left wing was destroyed and found in numerous pieces. A section of the wing's leading edge, approximately 6 feet in length, along with the wing's aileron was located on the building's roof. The wing's leading edge exhibited accordion damage throughout its span, with its wing flap bent and twisted, but still attached. The inboard half of the left wing remained attached to the airplane, while the outboard one-half was separated, bent and twisted. The left wing strut was bent 90 degrees and separated from both its lower and upper attach points.

The initial onsite examination of the wreckage revealed that the majority of the airplane's right wing came to rest in a near vertical position, with approximately 18 inches protruding through the impact opening of the roof. Further examination revealed that the wing had separated from the airplane, was crushed aft, and exhibited leading edge accordion damage through its span. It was also observed that 8 slash marks, similar to propeller slashes, were present. The slash marks originated on the upper surface of the wing, penetrating through the bottom of the wing and oriented in a diagonal presentation; forward right to aft left. The right wing strut and flap remained attached to the wing. Black transfer signatures were observed extending from the aft inboard area of the underside of the right wing flap diagonally forward to the center section of the flap. The signatures were similar to the black material covering the bow bumpers on the Beaver's floats.

An indentation signature, parallel to the longitudinal axis of the airplane and approximately 4 feet in length, was located on top of the mid-empennage section of the fuselage. When viewed from aft forward, the right side of the fuselage above the airplane's registration numbers exhibited transfer signatures perpendicular to the airplane's longitudinal axis.

The cabin/cockpit area was destroyed. Documentation of the airplane's instruments revealed that the RPM tach read 6128.4, the RPM gauge read 1,800, the suction gauge indicated a "0" reading, and the compass indicated a heading of 250 degrees. No other documentation of instrument readings was possible due to the destructive nature of the accident.

An examination of the Cessna's engine, performed by a representative of the engine manufacturer with NTSB oversight, failed to reveal any anomalies which would have precluded normal operation. The engine came to rest on the second floor of the impacted structure, with numerous engine accessory components located on the building's first floor, directly below the floor where the main wreckage came to rest.

The DHC-2 Beaver came to rest at coordinates 47 degrees 29.456 minutes north latitude and 122 degrees 12.969 west longitude, after making an emergency landing to the north on a grass median about 100 feet west of Runway 33 at RNT.

Both of the aircraft's floats were displaced approximately 20 degrees to the right of their parallel orientation to the aircraft's longitudinal axis, with the left float tilted about 45 degrees to the left; the right float remained upright and in its proper position. The right side of the aircraft's forward and aft spreader bars, when viewed from aft forward, had shifted forward about 30 degrees, while the left side of the spreader bars had shifted aft approximately 30 degrees.

Examination of the aircraft's left float revealed that the float was intact with no evidence of substantial damage. The float's bow bumper exhibited white transfer material signatures on a diagonal plane of orientation over an area of approximately 8 inches by 4 inches. A small piece of gray metal was observed imbedded in the bow bumper near its top extremity. Both of the float's front and rear spreader bar attach points remained intact, with both spreader bars secure at their respective attach points. Forward, aft, and diagonal strut attach points were intact. Forward, aft, and diagonal struts remained attached to their respective lower float attach points.

Examination of the aircraft's right float revealed that the float had sustained substantial damage. The left side of the float's bow bumper was twisted and bent, with an opening of approximately 6 inches extending aft along the longitudinal axis of the float into its metal structure. Additional damage to the float was sustained along the top and toward the left inside section of the float, located approximately 18 inches aft of the bow bumper and mooring cleat. Each side of the triangular area measured approximately 5 inches in length. Additional damage to the float was observed in the area just aft and adjacent to the aft strut attach point where the rear cabin stair support brace had punctured the top of the float. The examination also revealed the presence of a 36 inch long by 2 to 3 inch wide piece of gray metal, which was found wrapped around the aft strut, extending over the inside of the float and forward of the aft spreader bar. The piece of gray metal was later identified by a Cessna representative as being a piece of the Cessna 150's right aileron.

Damage to the airplane's structure was confined to the left and right fuselage areas, where the cabin and cockpit step support structures had become dislodged and reoriented from their original positions. The airplane's left main cabin door was punctured by the upper aft step support structure about 2 inches below the window and just forward of the door handle. An arching scrape mark was located prior to the puncture, approximately 14 inches in length on a diagonal orientation toward the aft lower corner of the door. Damage to the left side of the aircraft's fuselage was observed where the aft cabin step support attaches at its upper attach point. Puncture damage covering an area of 2 inches by 1 1/2 inches was observed.

Flight control continuity was confirmed throughout the airplane to all control surfaces. The flaps were observed in the full down position.

There was no physical evidence to indicate that the airplane's engine was damaged. The pilot reported to the IIC shortly after the accident that there were no anomalies with the engine during the flight. The aircraft's propeller was intact with the outboard 9 inches of all three propeller blades exhibiting leading edge nicks, gouges and chordwise scratches.


Postmortem examination of the flight instructor in the Cessna 150M was performed by the King County Medical Examiner's office, Seattle, Washington, on August 5, 2005. The cause of death was attributed to multiple blunt traumatic injuries. No findings which could be considered causal to the accident were reported. Toxicology studies on specimens from the flight instructor were conducted by the FAA Toxicological Laboratory, Oklahoma City, Oklahoma, and all tests were negative.

Postmortem examination of the dual student in the Cessna 150M was performed by the King County Medical Examiner's office, Seattle, Washington, on August 5, 2005. The cause of death was attributed to multiple blunt traumatic injuries. No findings which could be considered causal to the accident were reported. Toxicology studies on specimens from the pilot were conducted by the FAA Toxicological Laboratory, Oklahoma City, Oklahoma, and all tests were negative.



The Renton Federal Aviation Administration Contract Tower was operated by Serco Management Services, Inc., of Murfreesboro, Tennessee. The facility was open from 0700 to 2000 local time, October 1 to April 30 and between 0700 and 2100 May 1 to September 30. The airport has one runway, 15/33. At the time of the accident, runway 33 was in use.

A "Standard Terminal Area Radar System" (STARS) is displayed on the RNT tower display. Radar data is supplied to the STARS display from the Federal Aviation Administration's terminal radar approach control, which is located at the Seattle-Tacoma International Airport, Seattle, Washington. STARS receives the radar data and flight plan information and presents the information on a high resolution, color display, which allows the controller to monitor, control and accept hand-off of air traffic.

At the time of the accident, a developmental air traffic controller was working all of the RNT positions combined at the local control position. He was certified on the ground control, flight data, and clearance delivery positions but still in training on the local control position. Because of that, a certified controller (on-the-job training instructor) was sitting behind the developmental monitoring his performance. Both controllers supplied written statements relative to the accident in question, which are available in the public docket.

On August 25, 2005, with the exception of the airplane's propeller and floats, the DHC-2 Beaver was released to the owner's representative, ACE Aviation, of Renton, Washington.

On October 19, 2005, the propeller and floats of the DHC-2 Beaver, previously retained by the IIC, were released to the owner's representative, AV Tech Services, LLC, of Kent, Washington.

On November 1, 2005, the wreckage of the Cessna 150M was released to the owner's representative, AV Tech Services, LLC, of Kent, Washington.

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