SEA05FA158

A Cessna 150, N66234, and a de Havilland DHC-2 Beaver, N741DL, collided in flight while preparing to enter the downwind leg of the airport traffic pattern for runway 33. The collision occurred about one and one-half miles northeast of the airport. Both aircraft were under the control of a developmental air traffic controller who was being supervised by a certified controller. The Cessna pilot contacted the tower controller and was instructed to enter a right downwind via the forty-five. The controller advised, "...traffic ahead and to your right, one thousand six hundred, turning southbound, type unknown." The pilot did not respond. About 15 seconds later the pilot of another DHC-2 Beaver, N715JR, contacted the controller and was advised that the Cessna was passing behind him, was no factor, and to enter right downwind for runway 33. The pilot acknowledged. Approximately 20 seconds later the pilot of the accident DHC-2 Beaver made his initial contact with the controller, who replied, "…ok, you have traffic twelve o'clock, two miles, a Cessna, one thousand three hundred southbound." The pilot advised he was looking for the traffic. About 17 seconds passed when the controller instructed the pilot of the accident DHC-2 Beaver, "…enter downwind via the 45, you'll be following that Cessna ahead and to your right." The pilot responded, "Ok, we'll be landing on the water," and the controller replied, "Roger that, he's landing on the hard surface, you'll be doing a low approach over the water, understand." About 40 seconds passed, when the controller asked the pilot of the accident DHC-2 Beaver if he had the Cessna in sight, to which the pilot replied, "…ah, we've got an aircraft on downwind ahead of us in sight," with the controller acknowledging, "roger, follow that aircraft." The pilot acknowledged, stating later in his statement, "The Beaver ahead of me was given clearance to proceed as requested. I informed the tower that I had the traffic ahead and on downwind in sight and was told to follow him." About five seconds later the pilot of the other DHC-2 Beaver reported entering downwind and would be landing on the water, and approximately 30 seconds later the controller instructed the Cessna to proceed direct to the downwind. Less than five seconds passed before the controller advised the Cessna pilot, "and you have traffic off your right wing, has you in sight, one thousand six hundred, floatplane." The pilot of the Cessna replied, "…traffic in sight." Approximately 15 seconds later the controller confirmed that the accident DHC-2 Beaver would be landing on the water, with the pilot replying, "…affirmative. We have the aircraft on base." About five seconds later the controller asked the pilot of the accident DHC-2 Beaver, "…do you have the traffic that's passing underneath you still?" The pilot responded, "ah yah, base to final landing on the water." The Cessna's right wing glanced off the Beaver's left front float bow bumper before impacting the forward inboard side of the right float as the Beaver's propeller penetrated the upper outboard section of the right wing. A subsequent impact with the Cessna's empennage rendered the airplane uncontrollable, resulting in a steep uncontrolled descent prior to impacting a vacant school building. The pilot of the Beaver transmitted the collision information and subsequently landed with substantial damage to the airplane.

A Cessna 150, N66234, and a de Havilland DHC-2 Beaver, N741DL, collided in flight while preparing to enter the downwind leg of the airport traffic pattern for runway 33. The collision occurred about one and one-half miles northeast of the airport. Both aircraft were under the control of a developmental air traffic controller who was being supervised by a certified controller. The Cessna pilot contacted the tower controller and was instructed to enter a right downwind via the forty-five. The controller advised, "...traffic ahead and to your right, one thousand six hundred, turning southbound, type unknown." The pilot did not respond. About 15 seconds later the pilot of another DHC-2 Beaver, N715JR, contacted the controller and was advised that the Cessna was passing behind him, was no factor, and to enter right downwind for runway 33. The pilot acknowledged. Approximately 20 seconds later the pilot of the accident DHC-2 Beaver made his initial contact with the controller, who replied, "…ok, you have traffic twelve o'clock, two miles, a Cessna, one thousand three hundred southbound." The pilot advised he was looking for the traffic. About 17 seconds passed when the controller instructed the pilot of the accident DHC-2 Beaver, "…enter downwind via the 45, you'll be following that Cessna ahead and to your right." The pilot responded, "Ok, we'll be landing on the water," and the controller replied, "Roger that, he's landing on the hard surface, you'll be doing a low approach over the water, understand." About 40 seconds passed, when the controller asked the pilot of the accident DHC-2 Beaver if he had the Cessna in sight, to which the pilot replied, "…ah, we've got an aircraft on downwind ahead of us in sight," with the controller acknowledging, "roger, follow that aircraft." The pilot acknowledged, stating later in his statement, "The Beaver ahead of me was given clearance to proceed as requested. I informed the tower that I had the traffic ahead and on downwind in sight and was told to follow him." About five seconds later the pilot of the other DHC-2 Beaver reported entering downwind and would be landing on the water, and approximately 30 seconds later the controller instructed the Cessna to proceed direct to the downwind. Less than five seconds passed before the controller advised the Cessna pilot, "and you have traffic off your right wing, has you in sight, one thousand six hundred, floatplane." The pilot of the Cessna replied, "…traffic in sight." Approximately 15 seconds later the controller confirmed that the accident DHC-2 Beaver would be landing on the water, with the pilot replying, "…affirmative. We have the aircraft on base." About five seconds later the controller asked the pilot of the accident DHC-2 Beaver, "…do you have the traffic that's passing underneath you still?" The pilot responded, "ah yah, base to final landing on the water." The Cessna's right wing glanced off the Beaver's left front float bow bumper before impacting the forward inboard side of the right float as the Beaver's propeller penetrated the upper outboard section of the right wing. A subsequent impact with the Cessna's empennage rendered the airplane uncontrollable, resulting in a steep uncontrolled descent prior to impacting a vacant school building. The pilot of the Beaver transmitted the collision information and subsequently landed with substantial damage to the airplane.

History of flight

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, "...do 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 impac

History of flight

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, "...do 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 impac