NTSB Identification: ANC16FA065
14 CFR Part 91: General Aviation
Accident occurred Saturday, September 10, 2016 in Anchorage, AK
Probable Cause Approval Date: 05/11/2017
Aircraft: HEFTY Polar Cub, registration: N62905
Injuries: 1 Fatal.
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.
The private pilot departed in his float-equipped, experimental, amateur-built airplane during day visual meteorological conditions. According to a friend of the pilot, the purpose of the flight was to fly over a proposed hunting site and then return.
About 90 minutes later, multiple witnesses saw the airplane complete two, low-level, high-speed, 360° right turns over a residential neighborhood. The witnesses said that the airplane's first 360° turn was accomplished at an altitude between 150 and 200 ft above ground level, but the second turn was much lower. Witnesses near the accident site reported that, as the airplane completed the second, steep, 360° turn, the nose of the airplane pitched down, and the airplane began a rapid nose-down descent. The engine rpm then increased significantly, and the wings rolled level just before the airplane impacted a stand of tall trees adjacent to a home. The airplane subsequently descended onto a neighborhood road and came to rest inverted. A postcrash fire ensued about 30 seconds after impact, which quickly engulfed the entire airplane.
According family members and close friends, this was highly unusual behavior for this pilot.
Postaccident examination of the airplane's exhaust system revealed that the muffler can assembly was cracked around most of its circumference near the inlet portion of the muffler, which would have allowed exhaust gases to enter the cockpit/cabin. Toxicology tests revealed 48% carboxyhemoglobin (carbon monoxide) in the pilot's blood. The pilot was a nonsmoker, and nonsmokers normally have no more than 3% carboxyhemoglobin. The pilot's cause of death was extensive blunt force trauma including lacerations of the aorta, heart, and liver, and there was no soot found in his trachea. Although there was a postimpact fire, given the extensive blunt force injuries the pilot sustained and the lack of soot in his trachea, it is likely that the pilot's elevated carboxyhemoglobin level was from acute exposure to carbon monoxide during the 90-minute flight and not from postimpact fire.
Carboxyhemoglobin levels between 10% and 20% can result in confusion, impaired judgment, and difficulty concentrating, and the pilot's 48% carboxyhemoglobin level likely resulted in severe impairment.
No aircraft maintenance records were located for the airplane, which the pilot had built in 1996, so it is unknown when the muffler was last inspected or maintained. Additionally, due to the extensive postimpact fire, it was not possible to determine if the airplane was equipped with any type of carbon monoxide detection equipment. According to friends of the pilot, he conducted all maintenance on the airplane.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot's severe impairment from carbon monoxide poisoning in flight, which resulted in a loss of control and a subsequent collision with trees and terrain.
James "Curt" Hefty, 75, of Anchorage, Alaska, passed away on September 10th, 2016, while doing one of the things he loved most in the world: flying.
The National Transportation Safety Board traveled to the scene of this accident.
Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Anchorage, Alaska
Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf
Curt Hefty: http://registry.faa.gov/N62905
NTSB Identification: ANC16FA065
14 CFR Part 91: General Aviation
Accident occurred Saturday, September 10, 2016 in Anchorage, AK
Aircraft: HEFTY Polar Cub, registration: N62905
Injuries: 1 Fatal.
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.
HISTORY OF FLIGHT
On September 10, 2016, about 1630 Alaska daylight time, a float-equipped, experimental amateur-built, Hefty Polar Cub airplane, N62905, was destroyed following a loss of control and subsequent impact with tree-covered terrain in a residential neighborhood in Anchorage, Alaska. The private pilot, the sole occupant, was fatally injured. The airplane was registered to and operated by the pilot as a personal local flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight reportedly originated in southwest Anchorage from Jewell Lake about 1500, but the actual departure time and flight route are unknown.
According to family and friends of the pilot, the purpose of the flight was to fly over a proposed hunting site near Willow, Alaska, and then return to Anchorage. The friend related that the pilot and a group of friends were planning a fly-in hunt later in the week.
During on-scene interviews conducted by the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on the day of the accident, multiple witnesses consistently reported that they observed the airplane complete two, low-level, high-speed, 360° right turns over a residential neighborhood. The witnesses said that the airplane's first 360° turn was accomplished at an altitude between 150 and 200 ft above ground level, but the second turn was much lower. One homeowner stated that, as the airplane passed over his home, it was about 50 ft above his roofline. The witnesses also reported that the airplane's bank angle increased significantly on the second 360° right turn. One pilot-rated witness estimated that the airplane's bank angle was in excess of 60° during the second 360° turn. Multiple witnesses reported hearing the airplane's engine operating in a manner consistent with high power settings throughout both 360° turns.
Witnesses near the accident site reported that, as the airplane completed the second, steep, 360° right turn, the nose of the airplane pitched down, and it began a rapid nose-down descent. The engine rpm then increased significantly, and the wings rolled level just before the airplane impacted a stand of tall trees adjacent to a home. During the collision sequence, the airplane's floats were severed, and the airplane subsequently descended onto a neighborhood road, coming to rest inverted. A postimpact fire ensued about 30 seconds after impact, which quickly engulfed the entire airplane.
During a brief on scene interview with the NTSB IIC, a family member, along with a friend of the pilot, both reported that it was highly unusual and uncharacteristic behavior for the pilot to be flying as witnesses described.
PERSONNEL INFORMATION
The pilot, age 75, held a private pilot certificate with an airplane single-engine land rating; he did not hold a single-engine sea rating. In addition, he held a Federal Aviation Administration (FAA) repairman certificate specifically for the accident airplane. The pilot's most recent third-class, special issuance medical certificate, was issued on May 23, 2007, and contained the limitation: "Not valid for any class after May 31, 2008."
On the pilot's application for medical certificate, dated May 23, 2007, he indicated that his total aeronautical experience was about 2,200 flight hours. No personal flight records were located for the pilot.
AIRCRAFT INFORMATION
The airplane, which bears a resemblance to a Piper PA-11, had a rectangular, welded steel-tube structure that was covered with fabric. The wings, rudder, and horizontal stabilizer were all fabric covered. At the time of the accident, the airplane was equipped with a set of EDO 2000-series floats.
According to archived documents on file with the FAA certification office located in Oklahoma City, the airplane was built by the pilot from a set of purchased plans and was issued an FAA experimental airworthiness certificate with operating limitations on May 22, 1996. At the time the airworthiness certificate was issued, the airplane was equipped with a Continental Motors C-90-12-F engine.
At the time of the accident, the airplane was equipped with a Lycoming O-320-A2A engine, serial number L-9126-27, and a Catto composite propeller. No installation documentation for either the engine or propeller was located.
No aircraft maintenance records were located for the accident airplane. According to family members of the pilot, the airframe and engine logbooks were likely on board the airplane at the time of the accident. According to a family friend, the accident pilot performed all of the maintenance on the accident airplane.
METEOROLOGICAL INFORMATION
The closest official weather observation station to the accident site was located at the Ted Stevens Anchorage International Airport, about 10 miles to the east. On September 10, 2016, at 1553, the station was reporting, in part: wind 230° at 4 knots; visibility 10 statute miles; ceiling and clouds, few at 2,500 ft; temperature 63° F; dew point 43° F; altimeter 30.14 inches of mercury.
WRECKAGE AND IMPACT INFORMATION
Responding fire department and police personnel reported that, upon arrival, they discovered the inverted and burning wreckage on a neighborhood road, which was surrounded by tall trees. All of the airplane's major components were found at the main wreckage site. The airplane's longitudinal axis was oriented on a heading of 035° magnetic. Flight control continuity was established from the respective flight controls to the cabin area.
The airplane's first impact point was a stand of tall spruce trees about 120 ft from the wreckage point of rest. Broken tree branches and small portions of aircraft fabric that remained in the treetops marked the area.
The next impact point was a second stand of tall trees about 100 ft from the wreckage point of rest. The airplane's two EDO 2000-series floats were found entangled and suspended in the stand of tall trees.
The right wing was displaced slightly aft of its normal orientation to the fuselage, and the fabric on the underside of the wing was burned away. The aileron and flap remained attached to the wing, and the right flap appeared to be up. The leading edge of the right wing was slightly crushed and flattened in an aft direction, from about midspan to the wingtip. The inboard end of the wing and the right fuel tank were fire damaged.
The left wing was displaced aft about 45° from its normal orientation to the fuselage, and most of the fabric had burned away. The aileron and flap remained attached to the wing, and the left flap appeared to be up. The leading edge at the outboard end of the wing was flattened and crushed aft, with downward curling of the wingtip. The inboard end of the wing was extensively fire damaged, and the left fuel tank was incinerated.
The entire cockpit, baggage area, and fuselage extending to the vertical stabilizer were consumed by fire. Both wing lift struts remained attached to their respective wing and fuselage attach points.
The propeller hub assembly remained connected to the engine crankshaft, but the composite propeller blades were obliterated due to impact damage. The engine had impact and fire damage to the underside and front portion. Continuity of the drive train was established at the tachometer drive fitting on the accessory case when the propeller hub was moved by hand. The engine's four sparks plugs were examined and were dry with no unusual combustion signatures. The carburetor received impact damage. The engine control cables were either attached, or broken, at their respective carburetor control arms.
MEDICAL AND PATHOLOGICAL INFORMATION
A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, Anchorage, Alaska. The cause of death for the pilot was attributed to blunt force injuries. The autopsy also identified extensive lacerations of the aorta, heart, and liver. There was no soot identified in the tracheobronchial tree.
The FAA Bioaeronautical Sciences Research Laboratory performed toxicological examinations, which revealed 48% carboxyhemoglobin (carbon monoxide) in the pilot's blood. Additionally, amlodipine, metoprolol, naproxen, and rosuvastatin were detected in the pilot's blood and urine.
Carbon monoxide is an odorless, tasteless, colorless, nonirritating gas formed by hydrocarbon combustion. Carbon monoxide binds to hemoglobin with much greater affinity than oxygen, forming carboxyhemoglobin; elevated levels result in impaired oxygen transport and utilization. Early symptoms of carbon monoxide exposure may include headache, malaise, nausea, and dizziness. Carboxyhemoglobin levels between 10% and 20% can result in confusion, impaired judgment, and difficulty concentrating.
Nonsmokers may normally have up to 3% carboxyhemoglobin in their blood; heavy smokers may have levels of 10% to 15%. Family members and friends reported that the pilot was a nonsmoker.
Amlodipine is a prescription blood pressure medication also called Norvasc. Metoprolol is a beta blocking prescription medication, often called Lopressor or Toprol, that is used to treat high blood pressure and to prevent heart attacks in patients with coronary artery disease. Naproxen in an anti-inflammatory analgesic available over the counter with a variety of names, including Aleve. Rosuvastatin is a prescription medication to treat high cholesterol and is commonly marketed with the name Crestor. None of these medications adversely affect performance.
According to the NTSB chief medical officer's review of the pilot's autopsy and medical records obtained from the Veteran's Administration Hospital, Joint Base Elmendorf-Richardson, Anchorage, he had a history of hypertension, high cholesterol, coronary artery disease, and bladder neck obstruction. A copy of the NTSB' chief medical officer's factual report is available in the public docket for this accident.
TESTS AND RESEARCH
On December 2, 2016, after being notified by the FAA's Bioaeronautical Sciences Research Laboratory of the elevated level of carboxyhemoglobin in the pilot's blood, the NTSB IIC recovered the accident airplane's exhaust system for a detailed examination. The airplane's exhaust system consisted of a muffler covered by an exterior shroud assembly that provided ducted heat to the airplane's cockpit, cabin, and engine carburetor heat system. During the exhaust system examination, the NTSB IIC peeled open the shroud assembly, which revealed a severely degraded and damaged muffler can assembly. The muffler can was cracked around most of its circumference near the inlet portion of the muffler. The entire muffler assembly was then sent to the NTSB's Materials Laboratory for further examination.
The examination revealed that portions of the muffler can material were missing and that areas adjacent to the missing material had white, oxidized exhaust deposits. Cracks and corrosion on the interior surface of the exterior shroud in an area under a riveted doubler were also seen. A copy of the NTSB's Materials Laboratory Factual Report is included in the public docket for this accident.
ADDITIONAL INFORMATION
FAA Advisory Circular (AC) 91-59A, "Inspection and Care of General Aviation Aircraft Exhaust Systems," emphasizes the safety hazards of poorly maintained aircraft exhaust systems and highlights points at which exhaust system failures occur. In addition, the AC stresses the importance of having carbon monoxide detection equipment installed. Due to the extensive postcrash fire damage to the airplane, the NTSB was unable to determine if the accident airplane was equipped with any type of carbon monoxide detection equipment.
14 CFR Part 91: General Aviation
Accident occurred Saturday, September 10, 2016 in Anchorage, AK
Aircraft: HEFTY Polar Cub, registration: N62905
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 September 10, 2016 about 1630 Alaska daylight time, a float-equipped, experimental amateur-built, Hefty Polar Cub airplane, N62905, was destroyed following a loss of control and subsequent impact with tree-covered terrain in a residential neighborhood in Anchorage, Alaska. The pilot was fatally injured, and a postcrash fire incinerated the airplane. The airplane was registered to, and operated by, the pilot as a visual flight rules (VFR) personal local flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight reportedly originated in southwest Anchorage from Jewell Lake, about 1500, but the actual departure time and route of flight are unknown.
According to a friend of the pilot, the purpose of the flight was to fly over a proposed hunting site near Willow, Alaska, and then return to Anchorage. The friend related that the pilot and a group of friends were planning a fly-in hunt later in the week.
During on-scene interviews with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on September 10, multiple witnesses consistently reported that they observed the accident airplane complete two, low level, high speed, 360-degree right turns over the lower hillside neighborhood. The witnesses said that the accident airplane's first 360-degree turn was accomplished at an altitude between 150 and 200 feet above ground level (agl), but the second pass was much lower. One homeowner stated that as the airplane passed over his home, it was about 50 feet above his roofline.
The witnesses also reported that the accident airplane's bank angle increased significantly on the second 360-degree right turn. One pilot-rated witness that observed the airplane's steep turns estimated the bank angle in excess of 60 degrees during the second 360-degree turn.
Multiple witnesses reported hearing the airplane's engine operating in a manner consistent with high power settings throughout both 360-degree right turns.
Witnesses near the accident site reported that as the airplane completed the second, steep, 360-right turn, the nose of the airplane pitched down, and it began a rapid nose down descent. The engine rpm then increased significantly, and the wings rolled level just before impacting a stand of tall trees adjacent to a home. During the collision sequence the airplane's floats were severed, and the airplane subsequently descended onto a neighborhood road, coming to rest inverted. A postcrash fire ensued about 30 seconds after impact, which quickly engulfed the entire airplane.
The closest official weather observation station is located at the Ted Stevens Anchorage International Airport. On September 10, 2016, at 1553, an Aviation Routine Weather Report (METAR) was reporting, in part: Wind 230 degrees at 4 knots; visibility 10 miles; ceiling and clouds, few at 2,500 feet; temperature 63 degrees F; dew point 43 degrees F; altimeter 30.14 inHg.
James "Curt" Hefty, 75, of Anchorage, Alaska, passed away on Sept. 10, 2016, while doing one of the things he loved most in the world: flying.
The National Transportation Safety Board traveled to the scene of this accident.
Additional Participating Entity: Federal Aviation Administration / Flight Standards District Office; Anchorage, Alaska
Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf
Curt Hefty: http://registry.faa.gov/N62905
NTSB Identification: ANC16FA065
14 CFR Part 91: General Aviation
Accident occurred Saturday, September 10, 2016 in Anchorage, AK
Aircraft: HEFTY Polar Cub, registration: N62905
Injuries: 1 Fatal.
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.
HISTORY OF FLIGHT
On September 10, 2016, about 1630 Alaska daylight time, a float-equipped, experimental amateur-built, Hefty Polar Cub airplane, N62905, was destroyed following a loss of control and subsequent impact with tree-covered terrain in a residential neighborhood in Anchorage, Alaska. The private pilot, the sole occupant, was fatally injured. The airplane was registered to and operated by the pilot as a personal local flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight reportedly originated in southwest Anchorage from Jewell Lake about 1500, but the actual departure time and flight route are unknown.
According to family and friends of the pilot, the purpose of the flight was to fly over a proposed hunting site near Willow, Alaska, and then return to Anchorage. The friend related that the pilot and a group of friends were planning a fly-in hunt later in the week.
During on-scene interviews conducted by the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on the day of the accident, multiple witnesses consistently reported that they observed the airplane complete two, low-level, high-speed, 360° right turns over a residential neighborhood. The witnesses said that the airplane's first 360° turn was accomplished at an altitude between 150 and 200 ft above ground level, but the second turn was much lower. One homeowner stated that, as the airplane passed over his home, it was about 50 ft above his roofline. The witnesses also reported that the airplane's bank angle increased significantly on the second 360° right turn. One pilot-rated witness estimated that the airplane's bank angle was in excess of 60° during the second 360° turn. Multiple witnesses reported hearing the airplane's engine operating in a manner consistent with high power settings throughout both 360° turns.
Witnesses near the accident site reported that, as the airplane completed the second, steep, 360° right turn, the nose of the airplane pitched down, and it began a rapid nose-down descent. The engine rpm then increased significantly, and the wings rolled level just before the airplane impacted a stand of tall trees adjacent to a home. During the collision sequence, the airplane's floats were severed, and the airplane subsequently descended onto a neighborhood road, coming to rest inverted. A postimpact fire ensued about 30 seconds after impact, which quickly engulfed the entire airplane.
During a brief on scene interview with the NTSB IIC, a family member, along with a friend of the pilot, both reported that it was highly unusual and uncharacteristic behavior for the pilot to be flying as witnesses described.
PERSONNEL INFORMATION
The pilot, age 75, held a private pilot certificate with an airplane single-engine land rating; he did not hold a single-engine sea rating. In addition, he held a Federal Aviation Administration (FAA) repairman certificate specifically for the accident airplane. The pilot's most recent third-class, special issuance medical certificate, was issued on May 23, 2007, and contained the limitation: "Not valid for any class after May 31, 2008."
On the pilot's application for medical certificate, dated May 23, 2007, he indicated that his total aeronautical experience was about 2,200 flight hours. No personal flight records were located for the pilot.
AIRCRAFT INFORMATION
The airplane, which bears a resemblance to a Piper PA-11, had a rectangular, welded steel-tube structure that was covered with fabric. The wings, rudder, and horizontal stabilizer were all fabric covered. At the time of the accident, the airplane was equipped with a set of EDO 2000-series floats.
According to archived documents on file with the FAA certification office located in Oklahoma City, the airplane was built by the pilot from a set of purchased plans and was issued an FAA experimental airworthiness certificate with operating limitations on May 22, 1996. At the time the airworthiness certificate was issued, the airplane was equipped with a Continental Motors C-90-12-F engine.
At the time of the accident, the airplane was equipped with a Lycoming O-320-A2A engine, serial number L-9126-27, and a Catto composite propeller. No installation documentation for either the engine or propeller was located.
No aircraft maintenance records were located for the accident airplane. According to family members of the pilot, the airframe and engine logbooks were likely on board the airplane at the time of the accident. According to a family friend, the accident pilot performed all of the maintenance on the accident airplane.
METEOROLOGICAL INFORMATION
The closest official weather observation station to the accident site was located at the Ted Stevens Anchorage International Airport, about 10 miles to the east. On September 10, 2016, at 1553, the station was reporting, in part: wind 230° at 4 knots; visibility 10 statute miles; ceiling and clouds, few at 2,500 ft; temperature 63° F; dew point 43° F; altimeter 30.14 inches of mercury.
WRECKAGE AND IMPACT INFORMATION
Responding fire department and police personnel reported that, upon arrival, they discovered the inverted and burning wreckage on a neighborhood road, which was surrounded by tall trees. All of the airplane's major components were found at the main wreckage site. The airplane's longitudinal axis was oriented on a heading of 035° magnetic. Flight control continuity was established from the respective flight controls to the cabin area.
The airplane's first impact point was a stand of tall spruce trees about 120 ft from the wreckage point of rest. Broken tree branches and small portions of aircraft fabric that remained in the treetops marked the area.
The next impact point was a second stand of tall trees about 100 ft from the wreckage point of rest. The airplane's two EDO 2000-series floats were found entangled and suspended in the stand of tall trees.
The right wing was displaced slightly aft of its normal orientation to the fuselage, and the fabric on the underside of the wing was burned away. The aileron and flap remained attached to the wing, and the right flap appeared to be up. The leading edge of the right wing was slightly crushed and flattened in an aft direction, from about midspan to the wingtip. The inboard end of the wing and the right fuel tank were fire damaged.
The left wing was displaced aft about 45° from its normal orientation to the fuselage, and most of the fabric had burned away. The aileron and flap remained attached to the wing, and the left flap appeared to be up. The leading edge at the outboard end of the wing was flattened and crushed aft, with downward curling of the wingtip. The inboard end of the wing was extensively fire damaged, and the left fuel tank was incinerated.
The entire cockpit, baggage area, and fuselage extending to the vertical stabilizer were consumed by fire. Both wing lift struts remained attached to their respective wing and fuselage attach points.
The propeller hub assembly remained connected to the engine crankshaft, but the composite propeller blades were obliterated due to impact damage. The engine had impact and fire damage to the underside and front portion. Continuity of the drive train was established at the tachometer drive fitting on the accessory case when the propeller hub was moved by hand. The engine's four sparks plugs were examined and were dry with no unusual combustion signatures. The carburetor received impact damage. The engine control cables were either attached, or broken, at their respective carburetor control arms.
MEDICAL AND PATHOLOGICAL INFORMATION
A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, Anchorage, Alaska. The cause of death for the pilot was attributed to blunt force injuries. The autopsy also identified extensive lacerations of the aorta, heart, and liver. There was no soot identified in the tracheobronchial tree.
The FAA Bioaeronautical Sciences Research Laboratory performed toxicological examinations, which revealed 48% carboxyhemoglobin (carbon monoxide) in the pilot's blood. Additionally, amlodipine, metoprolol, naproxen, and rosuvastatin were detected in the pilot's blood and urine.
Carbon monoxide is an odorless, tasteless, colorless, nonirritating gas formed by hydrocarbon combustion. Carbon monoxide binds to hemoglobin with much greater affinity than oxygen, forming carboxyhemoglobin; elevated levels result in impaired oxygen transport and utilization. Early symptoms of carbon monoxide exposure may include headache, malaise, nausea, and dizziness. Carboxyhemoglobin levels between 10% and 20% can result in confusion, impaired judgment, and difficulty concentrating.
Nonsmokers may normally have up to 3% carboxyhemoglobin in their blood; heavy smokers may have levels of 10% to 15%. Family members and friends reported that the pilot was a nonsmoker.
Amlodipine is a prescription blood pressure medication also called Norvasc. Metoprolol is a beta blocking prescription medication, often called Lopressor or Toprol, that is used to treat high blood pressure and to prevent heart attacks in patients with coronary artery disease. Naproxen in an anti-inflammatory analgesic available over the counter with a variety of names, including Aleve. Rosuvastatin is a prescription medication to treat high cholesterol and is commonly marketed with the name Crestor. None of these medications adversely affect performance.
According to the NTSB chief medical officer's review of the pilot's autopsy and medical records obtained from the Veteran's Administration Hospital, Joint Base Elmendorf-Richardson, Anchorage, he had a history of hypertension, high cholesterol, coronary artery disease, and bladder neck obstruction. A copy of the NTSB' chief medical officer's factual report is available in the public docket for this accident.
TESTS AND RESEARCH
On December 2, 2016, after being notified by the FAA's Bioaeronautical Sciences Research Laboratory of the elevated level of carboxyhemoglobin in the pilot's blood, the NTSB IIC recovered the accident airplane's exhaust system for a detailed examination. The airplane's exhaust system consisted of a muffler covered by an exterior shroud assembly that provided ducted heat to the airplane's cockpit, cabin, and engine carburetor heat system. During the exhaust system examination, the NTSB IIC peeled open the shroud assembly, which revealed a severely degraded and damaged muffler can assembly. The muffler can was cracked around most of its circumference near the inlet portion of the muffler. The entire muffler assembly was then sent to the NTSB's Materials Laboratory for further examination.
The examination revealed that portions of the muffler can material were missing and that areas adjacent to the missing material had white, oxidized exhaust deposits. Cracks and corrosion on the interior surface of the exterior shroud in an area under a riveted doubler were also seen. A copy of the NTSB's Materials Laboratory Factual Report is included in the public docket for this accident.
ADDITIONAL INFORMATION
FAA Advisory Circular (AC) 91-59A, "Inspection and Care of General Aviation Aircraft Exhaust Systems," emphasizes the safety hazards of poorly maintained aircraft exhaust systems and highlights points at which exhaust system failures occur. In addition, the AC stresses the importance of having carbon monoxide detection equipment installed. Due to the extensive postcrash fire damage to the airplane, the NTSB was unable to determine if the accident airplane was equipped with any type of carbon monoxide detection equipment.
14 CFR Part 91: General Aviation
Accident occurred Saturday, September 10, 2016 in Anchorage, AK
Aircraft: HEFTY Polar Cub, registration: N62905
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 September 10, 2016 about 1630 Alaska daylight time, a float-equipped, experimental amateur-built, Hefty Polar Cub airplane, N62905, was destroyed following a loss of control and subsequent impact with tree-covered terrain in a residential neighborhood in Anchorage, Alaska. The pilot was fatally injured, and a postcrash fire incinerated the airplane. The airplane was registered to, and operated by, the pilot as a visual flight rules (VFR) personal local flight under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight reportedly originated in southwest Anchorage from Jewell Lake, about 1500, but the actual departure time and route of flight are unknown.
According to a friend of the pilot, the purpose of the flight was to fly over a proposed hunting site near Willow, Alaska, and then return to Anchorage. The friend related that the pilot and a group of friends were planning a fly-in hunt later in the week.
During on-scene interviews with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on September 10, multiple witnesses consistently reported that they observed the accident airplane complete two, low level, high speed, 360-degree right turns over the lower hillside neighborhood. The witnesses said that the accident airplane's first 360-degree turn was accomplished at an altitude between 150 and 200 feet above ground level (agl), but the second pass was much lower. One homeowner stated that as the airplane passed over his home, it was about 50 feet above his roofline.
The witnesses also reported that the accident airplane's bank angle increased significantly on the second 360-degree right turn. One pilot-rated witness that observed the airplane's steep turns estimated the bank angle in excess of 60 degrees during the second 360-degree turn.
Multiple witnesses reported hearing the airplane's engine operating in a manner consistent with high power settings throughout both 360-degree right turns.
Witnesses near the accident site reported that as the airplane completed the second, steep, 360-right turn, the nose of the airplane pitched down, and it began a rapid nose down descent. The engine rpm then increased significantly, and the wings rolled level just before impacting a stand of tall trees adjacent to a home. During the collision sequence the airplane's floats were severed, and the airplane subsequently descended onto a neighborhood road, coming to rest inverted. A postcrash fire ensued about 30 seconds after impact, which quickly engulfed the entire airplane.
The closest official weather observation station is located at the Ted Stevens Anchorage International Airport. On September 10, 2016, at 1553, an Aviation Routine Weather Report (METAR) was reporting, in part: Wind 230 degrees at 4 knots; visibility 10 miles; ceiling and clouds, few at 2,500 feet; temperature 63 degrees F; dew point 43 degrees F; altimeter 30.14 inHg.
Those who may have information that might be relevant to the National Transportation Safety Board investigation may contact them by emaileyewitnessreport@ntsb.gov, and any friends and family who want to contact investigators about the accident should email assistance@ntsb.gov.
AFD Assistant Chief Erich Scheunemann said fire crews on scene had confirmed Hefty was the only person onboard when the plane crashed. National Transportation Safety Board spokesman Clint Johnson said a dog was also onboard and died as well.
APD said multiple calls were made to 911 reporting the crash around 4:30 p.m., spokeswoman Jennifer Castro said in a phone interview. The crash occurred in the area of Crooked Creek Drive and O’Malley Road, officials said.
Scheunemann confirmed the aircraft was on fire, but has since been put out.
“It appears no residential homes were affected by the crash,” police said in a statement.
Roger Heiligenthal was walking his dog Chinook when he heard the plane overhead.
“He circled once and then a second time,” Heiligenthal said. “And as he’s circling, instead of flying level with the horizon — I’m not a pilot — but he was sort of tipped like this, so the wings were tipped inward and he kept circling as if he might have been in distress.”
Heiligenthal said when the pilot circled a third time, he knew there was a problem.
“The next thing I know, he was right there in front of us. Hit the trees, and just came barreling in,” he recalled.
The plane crashed through trees and came to rest on the roadway near Heiligenthal, catching fire.
“I kept yelling and yelling, ‘help, help!’” he said. “Called 911 and they were there in less than five minutes.”
Carolyn Nickles said she also witnessed the crash after hearing the plane pass by.
“I stood up and decided to go around that house and that’s when I saw the plane nose dive,” she said. “I didn’t see the whole plane. I knew it was definitely going to go. And then the huge impact afterwards.”
Heiligenthal said he believes if he had gone on his walk a minute later, he and Chinook would likely have been victims as well.
“I had no clue that he was going to be coming in my direction,” he said. “But it happened so fast and I’m just thankful for myself and my dog but I’m also grieving for the family of the pilot. I do grieve for the family because it’s just one of those things that you never know. You never know.”
The NTSB and the Federal Aviation Administration have been notified of the crash and are investigating. Johnson said the scene would cleared by the end of the night and the wreckage moved to a hangar for further examination.
He said the plane has been identified as a homebuilt “Polar Cub,” which is similar to a Piper Super Cub plane in structure and appearance. Johnson said it was too early in the investigation to rule anything out for the cause of the crash, and they have not yet identified any major contributions.
The NTSB is asking that if anyone witnessed the crash or saw the plane flying in the area just prior to the crash to please call 907-782-4849 if they have not already been interviewed.
Johnson said there was no property damage outside of the trees the plane struck, and no one else was injured by the crash.
Source: http://www.ktva.com
A small, homemade floatplane crashed and burst into flames on a street in a major residential subdivision on the Anchorage Hillside Saturday afternoon, killing the pilot, the only person on board, and his dog, authorities said.
No home was struck or damaged and a man walking his dog on the street just as the single-engine plane came down was uninjured, they said.
The crash was reported at 4:30 p.m. on Crooked Tree Drive just north of Treeline Court. The site was less than 1 mile from the O'Malley Road fire station, and crews were on scene within minutes and quickly extinguished the blaze, said Assistant Anchorage Fire Chief Erich Scheunemann.
Neighbors reported hearing and seeing the plane circling low over houses and treetops. One said it made a pass at a safe altitude before making a second pass much closer to the ground just before it crashed.
The skeletal aluminum frame of the plane was upside down on the side of the road, a blackened, downed spruce tree nearby.
A woman from the State Medical Examiner's Office first removed the dog from the incinerated plane, wrapping it in a white cloth she carried with both hands. Then the pilot's body was removed in a shroud on a stretcher.
The cause of the crash wasn't immediately known. Clint Johnson, chief of the National Transportation Safety Board's Anchorage regional office, was on scene and leading the investigation with assistance from the Anchorage Police Department, which had interviewed some of the witnesses.
Johnson said the aircraft was a homemade plane similar to a Super Cub. The plane first clipped some trees before crashing and its floats remained stuck in the trees.
Johnson said the plane was fueled by gasoline stored in wing tanks, which ignited and burned the plane's fabric shell and partially melted its aluminum frame.
Authorities had not determined the identity of the pilot Saturday evening and Johnson said they were assuming it was man, though they weren't positive. Police had an idea about who the pilot was, and some officers were with the family of that person, Johnson said.
Though the plane was badly burned, some cockpit instruments might yield clues about what happened, he said.
Johnson said he hadn't determined where the plane had begun its flight. He said he wasn't sure yet about the plane's registration number.
Keith Kniegge, who lives on Double Tree Court, a nearby street, said he was sitting at his computer when he heard the plane.
"It was really low, really close to our house," Kniegge said.
He said the plane came from the south and banked right as it headed toward Crooked Tree Drive.
Johnson said he was at his home in South Anchorage when he heard sirens. Then he got the call it was a plane crash.
While a lot of the clues that might explain the crash were burned, the investigation would benefit from the neighbors who saw and heard what happened, Johnson said.
"We're blessed with a number of witnesses, a lot of them pilot-rated," Johnson said at an impromptu news conference at the scene. The witnesses told authorities the pilot had made a couple of low passes over the neighborhood before crashing, Johnson said, barely missing the pedestrian and his dog.
Source: http://www.adn.com
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