A preliminary accident report released by the National Transportation Safety Board details the moments from the surviving pilot's point of view that led to the Southeast Alaska flightseeing plane collision that left six people dead and 10 others injured last week.

"He saw a flash from his left side"

The surviving pilot was flying a DHC-3 Turbine Otter floatplane operated by Taquan Air. In the NTSB report released Wednesday, he says he didn't see any potential conflicting traffic on his flight display during his descent.

The pilot told NTSB that his flight from the Misty Fjords area was going normally. He said he had descended and was maneuvering the plane to show passengers a waterfall near Mahoney Lake when the collision occurred.

His flight display included Automatic Dependent Surveillance-Broadcast system data. According to the report, he last recalled looking at the display while flying over Carroll Inlet.

"Just prior to the collision, he saw a flash from his left side, and experienced a large, loud impact," the NTSB report states. "According to the pilot, the [Otter] airplane then rolled right and pitched about 40 degrees nose down toward the water in George Inlet. He stated that he was able to maintain some control and flare the airplane prior to impact."

The pilot told NTSB he believes his plane hit the water just five seconds after the collision.

"The airplanes collided"

Both planes were based at the Ketchikan Harbor Seaplane Base. At the time of the collision, they were both returning to the area after taking passengers to see the Misty Fjords National Monument, which is located around 30 nautical miles northeast of Ketchikan.

Weather conditions that day included high overcast skies with 9 mph southeast winds, according to the Associated Press.

At around 12:21 p.m. on May 13, a de Havilland DHC-2 Beaver floatplane, operated by Mountain Air Service, and a de Havilland DHC-3 Turbine Otter floatplane, operated by Taquan Air, collided in midair about 7 miles northeast of Ketchikan.

Everyone aboard the Beaver, a pilot and four passengers, died in the collision. One passenger on the Otter also died, while nine others sustained serious injuries. The pilot had minor injuries.

According to the NTSB report, the Beaver was destroyed in the collision after an uncontrolled descent and impact with tree-covered terrain and water.

The Otter sustained substantial damage during the collision and impact with the water.

Preliminary flight track data in the report shows the Otter was traveling southwest at about 3,700 feet. It was gradually descending at 126 knots, about 145 mph, when it crossed the east side of the George Inlet.

The Beaver was traveling west/southwest at about 3,350 feet at 107 knots, about 123 mph, when it also crossed the east side of the George Inlet. The planes collided near the west side of the inlet, east of Mahoney Lake and data signals were lost.

"The wreckage was scattered"

Most of the wreckage from the Otter was found 80 feet underwater, about 400 feet off the east shore of the George Inlet. It was just under 2 miles northeast of the Beaver wreckage.

The Otter's floats were separated and found tied off by rescue personnel to a tree about 65 feet north from the main wreckage.

The report says the Beaver broke up in-flight after the collision. The wreckage was scattered over the water and mountainous terrain northeast of Mahoney Lake on the west shore of George Inlet.

The main wreckage — which included the floats, engine, firewall, instrument panel, lower fuselage structure and right fuselage structure — was located in saltwater near the mouth of Mahoney Creek. According to the report, the debris field was about 2,000-feet long by about 1,000-feet wide.

The Beaver's right wing wreckage had several cuts leading from the right aileron inboard to the wing root consistent with propeller blades. According to the NTSB, each cut penetrated further inboard and forward onto the wing structure. The cuts also had "distinct downward deformation" of the upper and lower wing skins — meaning the propeller blades from the Otter went through the Beaver from behind, eventually moving through its passenger compartment on the right side.

The NTSB report revealed that neither plane was required to be equipped with crash-worthy flight data or cockpit voice recorders; neither plane had them.

Several avionics components and personal electronic devices were recovered from the wreckage. They were shipped to the NTSB vehicle recorders laboratory in Washington, D.C. for examination.

Investigations involving fatalities and other major NTSB investigations currently take between 12 and 24 months to complete, according to a May 22 release.

"Part 135 is on our most wanted"

The same NTSB release states both aircrafts were operating under Part 135 of Federal Aviation Administration regulations that govern the operation of business and charter flights.

The agency is again calling for stricter recommendations on for-hire operations that fall under Part 135, including implementation of safety management systems, recording and analyzing flight data, and ensuring pilots receive controlled-flight-into-terrain avoidance training.

"A customer who pays for a ticket should trust that the operator is using the industry's best practices when it comes to safety,'' said NTSB chairman Robert L. Sumwalt. "And it shouldn't matter if the operator has one airplane or 100. Travelers should have an equivalent level of safety regardless of the nature of the flight for which they paid."

The release explained Part 135 aircraft flight operations are on the 2019–2020 Most Wanted List of transportation safety improvements for the NTSB. Sumwalt said the recent incidents in Alaska underscore the urgency for change. 

Officials stated major passenger airlines, which operate under Part 121, have adopted these measures and have seen an improvement in safety.

Cassie Schirm contributed information to this report.

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