Wednesday, March 16, 2016

Cessna 207 Skywagon, Yute Air, N1653U: Fatal accident occurred May 30, 2015 in Bethel, Alaska

Carbon monoxide found in pilot’s body after 2015 Yute Air crash

A Washington pilot who died in the crash of a Yute Air plane during a maintenance flight near Bethel last year had moderate levels of a toxic gas in his system, which National Transportation Safety Board investigators believe came from the aircraft's engine.

Olympia, Washington, resident Blaze Highlander, 47, died when the Cessna 207 he was flying crashed into the Kwethluk River on May 30. The plane, reported missing on a 3 ½-hour flight out of Bethel that morning after recent engine maintenance, was found about 40 miles southeast the next day. Highlander, the pilot and sole occupant, was discovered dead in the wreckage by investigators.

The NTSB's June preliminary report on the crash found that GPS-based telemetry data being broadcast by the aircraft tracked it to an altitude of 475 feet before it struck a tree and plunged into the river. Clint Johnson, the NTSB’s Alaska chief, said it was unlikely weather -- visibility was reportedly “unrestricted” in Bethel on the day of the crash -- would prove to be a factor in the crash.

An NTSB toxicology examination of Highlander’s blood released Monday found a 21 percent saturation of carbon monoxide, a gas found in engine exhausts that can cause symptoms ranging from disorientation to death over time.

A fact sheet on carbon monoxide from the U.S. Centers for Disease Control and Prevention states that carbon monoxide saturation greater than 2 percent in nonsmokers or 9 percent in smokers “strongly supports a diagnosis of CO poisoning.”

Millicent Hoidal, the NTSB investigator examining the Yute Air crash, said Tuesday the most likely source for the carbon monoxide in Highlander’s system was the plane’s Continental Motors IO-520 engine. Further details on how that happened are set to be released in a May factual report on the crash.

“What we know is that the carbon monoxide did come from the airplane,” Hoidal said. “It wasn’t something that he had before he got in the airplane.”

Hoidal said that despite the toxicology findings, it’s not clear how severely impaired by the gas Highlander may have been. She said typical blood saturation levels found in carbon monoxide poisonings range from 50 to 60 percent.

“CO affects different people in different ways,” Hoidal said. “He may have been feeling the effects of it, but to what degree it’s difficult to tell.”

The Yute Air crash is one of several fatal 2015 events being covered this year by the Smithsonian Channel series “Alaska Aircrash Investigations,” which has prompted the NTSB to release factual dockets of information on crashes ahead of the air dates for episodes involving them.

In addition to the toxicology report, the docket released for the Yute Air crash includes several photos of the wreckage and crash site, as well as a drawing of its engine exhaust system that includes a marked cabin heat outlet. A Continental Motors air safety investigator is among the company officials participating in the NTSB investigation.

The “Alaska Aircrash Investigations” episode covering Highlander’s death will air at 8 p.m. Sunday. It will also cover another fatal crash last summer, in which 54-year-old Michael Zagula died when his plane hit trees during low passes over his daughter’s Trapper Creek wedding reception. On Tuesday, the NTSB said marijuana and diazepam were found in Zagula’s system, but it couldn't determine whether they were a factor in that crash.

Original article can be found here:

NTSB Identification: ANC15FA032

14 CFR Part 91: General Aviation
Accident occurred Saturday, May 30, 2015 in Bethel, AK
Aircraft: CESSNA 207, registration: N1653U
Injuries: 1 Fatal.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

On May 30, 2015, about 1130 Alaska daylight time, a Cessna 207, N1653U, sustained substantial damage after impacting trees about 40 miles southeast of Bethel, Alaska. The airplane was being operated by Yute Air, Bethel, Alaska as a visual flight rules (VFR) postmaintenance flight under Title 14, CFR Part 91, when the accident occurred. The commercial pilot, the sole occupant, sustained fatal injuries. Visual meteorological conditions were reported in the area of the accident, and company flight following procedures were in effect. The accident flight originated at the Bethel Airport, Alaska about 0830, with an expected return time of 1200.

About 1415, flight coordination personnel from Yute Air in Bethel notified the Director of Operations (DO) that the accident airplane was overdue. About 1435 the DO notified the Federal Aviation Administration (FAA) who issued an alert notice (ALNOT). About 1532, an aerial search was initiated by Yute Air, Alaska State Troopers, Alaska Air National Guard as well as other air operators and Good Samaritans. On May 31, about 1730 searchers discovered the airplane's submerged and fragmented wreckage in a river slough. 

On June 1, the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), along with an additional NTSB investigator, an inspector from the Anchorage Flight Standards District Office (FSDO), and members of the Alaska State Troopers, traveled to the accident scene by helicopter and river boats. 

The main wreckage was located submerged in a fast flowing braided river that was surrounded by trees. An area believed to be the initial impact point was marked by a broken treetop, atop about a 30 foot tall birch tree. From the initial impact point the airplane traveled northbound, about 350 feet, coming to rest on its left side, and in the fast moving river water. The engine separated from the airplane and it was located submerged upstream and in the main river channel. The pilot's body was discovered still restrained within the submerged fuselage. 

An on-scene documentation of the debris field was completed, and a detailed wreckage examination is pending following recovery of the airplane. 

The accident airplane was equipped with automatic dependent surveillance-broadcast (ADS-B) technology. In typical applications, the ADS-B capable aircraft uses an ordinary Global Positioning System (GPS) receiver to derive its precise position from the Global Navigation Satellite System (GNSS) constellation, and then combines that position with any number of aircraft parameters, such as speed, heading, altitude, and aircraft registration number. This information is then simultaneously broadcast to other ADS-B capable aircraft, and to ADS-B ground, or satellite communications transceivers, which then relay the aircraft's position and additional information to Air Traffic Control centers in real time.

A preliminary NTSB review of ADS-B data archived by the Anchorage Air Route Traffic Control Center (ARTCC) showed that the accident airplane was transmitting data for portions of the accident flight. At the last recorded ADS-B position, which was about 6 miles southwest from the accident site, the airplane was flying at an altitude of approximately 475 feet mean seal level (msl), while traveling in an easterly-northeasterly direction. A detailed NTSB analysis of the archived ADS-B data is pending.

The airplane was equipped with a Continental Motors IO-520 engine. A detailed NTSB examination of the engine is pending.

The closest weather reporting facility was Bethel, about 40 miles northwest of the accident site. At 1053, an aviation routine weather report (METAR) was reporting, in part: Wind 210 degrees at 10 knots; visibility, 10 statute miles; clouds and sky condition, few at 12000 feet, scattered at 2000 feet; temperature, 16 degrees C; dew point, 9 degrees C; altimeter, 30.12 inHG.

FAA Flight Standards District Office:     FAA Anchorage FSDO-03

No comments: