# NTSB CEN11FA431: Bosonetto Thorp T-18, N8AL, Howell, MI, June 29, 2011 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: June 29, 2011, 19:15 local (23:15 UTC) - Place: Howell, MI - Coordinates: 42.623611, -83.968612 - Nearby events: https://openairdocs.org/map.md?lat=42.6236&lon=-83.9686&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR pattern final: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed, report May 14, 2014 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration East Michigan FSDO - NTSB case key (mKey): 80942 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11FA431 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/80942/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=80942 - Page: https://openairdocs.org/ntsb/CEN11FA431 ## Probable cause The pilot's failure to maintain airplane control and airspeed during final approach, which resulted in an aerodynamic stall/spin at a low altitude. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Bosonetto Allen R. THORP T-18, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=89510F1), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Bosonetto Allen R. THORP T-18, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=89510F1), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach-VFR pattern final: Abrupt maneuver](https://openairdocs.org/ntsb-events/270); cases with it: [Bosonetto Allen R. THORP T-18, 1 case](https://openairdocs.org/ntsb-events/270/sequence.md?model=89510F1), [All aircraft, 346 cases](https://openairdocs.org/ntsb-events/270/sequence.md) - [Approach-VFR pattern final: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Bosonetto Allen R. THORP T-18, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=89510F1), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Approach-VFR pattern final: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241); cases with it: [Bosonetto Allen R. THORP T-18, 1 case](https://openairdocs.org/ntsb-events/241/sequence.md?model=89510F1), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Bosonetto Allen R. THORP T-18, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=89510F1), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The purpose of the accident flight was for the pilot to obtain a flight review in the airplane that he owned. A witness reported seeing the airplane at a higher-than-normal glidepath to the runway and traveling at a slow airspeed while in a forward-slip maneuver. (A forward slip is a flight maneuver used to increase the descent rate, while maintaining airplane pitch and airspeed.) The witness stated that, while the airplane was in the forward slip and losing altitude, it suddenly entered a right spin and descended out of his view. Another witness reported seeing the airplane yawing side-to-side as it approached the runway and then hearing the engine increase to full power as the airplane simultaneously pitched up. The airplane then nosed over and descended into his front yard. A postaccident examination of the airplane revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The low-altitude stall/spin encountered during final approach was likely not recoverable. Toxicological testing revealed the presence of several medications in both the pilot and flight instructor; however, it is not likely that they resulted in any impairment. ## Factual narrative HISTORY OF FLIGHT On June 29, 2011, at 1915 eastern daylight time, an experimental amateur-built Bosonetto model Thorp T-18, N8AL, was substantially damaged when it impacted terrain and a house while maneuvering to land at the Livingston County Airport (OZW) near Howell, Michigan. The pilot and flight instructor were fatally injured. The airplane was registered to and operated by the private pilot under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Day visual meteorological conditions prevailed for the instructional flight, which originated at an unknown time from Canton-Plymouth-Mettetal Airport (1D2) near Plymouth, Michigan. The purpose of the accident flight was for the pilot to obtain a flight review. A witness to the accident, who was located in his airplane near the departure end of runway 31, reported seeing the airplane in the traffic pattern for runway 31. He stated that after the airplane had turned onto the final approach it was higher than the normal glide-path to the runway and appeared to be traveling at a slow airspeed while in a forward-slip maneuver. (A forward slip is a flight maneuver used to increase the descent rate, while maintaining airplane pitch and airspeed.) The witness stated that while the airplane was in the forward-slip, losing altitude, it suddenly entered a spin to the right and descended out of his view. Another witness, who was inside his residence located along the final approach path, reported that he saw the airplane yawing side-to-side as it approached runway 31. He stated that he heard the airplane engine increase to what sounded like full power simultaneously as the airplane pitched-up. The airplane then nosed-over and descended into his front yard before ultimately colliding with the south wall of his residence. The witness reported that the engine continued to operate at full power until the airplane collided with his residence. Another witness, who was driving westbound on M-59 toward the airport, reported seeing the airplane on final approach to runway 31 when it suddenly rolled to the left and right before it descended behind a nearby treeline and out of his sightline. PERSONNEL INFORMATION -- Pilot -- According to Federal Aviation Administration (FAA) records, the pilot, age 43, held a private pilot certificate with a single engine land airplane rating. His last aviation medical examination was completed on November 7, 2006, when he was issued a third-class medical certificate with no limitations or restrictions. A search of FAA records showed no previous accidents, incidents, or enforcement proceedings. The most recent pilot logbook entry was dated November 13, 2010. At that time, the pilot had accumulated 166.3 hours total flight time. The logbook indicated that all of his flight experience had been completed in single-engine land airplanes, which included 43.4 hours in the accident airplane. The first flight in the accident airplane was dated February 8, 2009.The logbook indicated that he had flown 13.2 hours during the past year; none of that time was during the previous 6 months. However, the accident airplane's hour meter suggested that the pilot could have flown as many as 6.6 hours in the accident airplane during the 6 month period preceding the accident. The pilot's previous flight review was completed on April 5, 2009, in a Cessna model 152 airplane. The pilot's flight logbook included an endorsement to operate tailwheel equipped airplanes, which was dated February 17, 2007. -- Flight Instructor -- According to FAA records, the flight instructor, age 70, held a commercial pilot certificate with single engine land airplane and instrument airplane ratings. He also held a flight instructor certificate with single engine airplane and instrument airplane ratings. His last aviation medical examination was completed on December 24, 2010, when he was issued a third-class medical certificate with a limitation that he wear lenses for distance vision and possess glasses for near vision. A search of FAA records showed no previous accidents, incidents, or enforcement proceedings. The most recent pilot logbook entry was dated July 1, 2010, when the flight instructor completed a flight review in a Piper model PA-28R airplane. The logbook did not include any forwarded flight times, and as such, an accurate flight history could not be determined with the information collected during the investigation. According to FAA records, on December 13, 2006, the flight instructor reported having accumulated 4,750 total flight hours on his application for a medical certificate. He did not report his flight experience on subsequent medical applications. The flight instructor kept a provisional record of his completed flights in his personally owned Piper model PA-28R airplane. According to this airplane flight log, his last recorded flight was completed on June 27, 2011. He had flown the Piper model PA-28R airplane 100 hours during the past year, 45 hours during the prior 6 months, 19 hours during previous 90 days, and 4 hours during the preceding 30 days. The flight instructor reportedly had not flown with the pilot or in the accident airplane before the accident flight. AIRCRAFT INFORMATION The accident airplane was a 1982 Bosonetto model Thorp T-18 amateur-built airplane, serial number (s/n) 238. A 150-horsepower Lycoming model O-320-A1A reciprocating engine, s/n L-2285-27, powered the airplane. The airplane was equipped with a fixed-pitch, two blade, Sensenich model W66LM74 wood propeller. The tail wheel-equipped airplane had a maximum takeoff weight of 1,600 pounds. The accident airplane was issued an experimental airworthiness certificate on November 10, 1982. The airplane was reissued an airworthiness certificate on July 9, 1987, after it was modified with a new engine and propeller combination. The airplane hour meter indicated 268.7 hours at the accident site. The airframe had accumulated a total service time of577.1 hours at the time of the accident. The engine had accumulated 127.9 hours since a field overhaul on July 9, 1987. The last condition inspection was completed on June 1, 2011, at 571.5 total airframe hours. A postaccident review of the maintenance records found no history of unresolved airworthiness issues. METEOROLOGICAL INFORMATION At 1914, the OZW automated surface observing system (ASOS) reported: wind from 300 degrees at 7 knots, visibility 10 miles, clear sky, temperature 25 degrees Celsius, dew point 8 degrees Celsius, and an altimeter setting of 30.06 inches of mercury. AERODROME INFORMATION The Livingston County Airport (OZW) was located about 3 miles northwest of Howell, Michigan, was served by a single runway: 13/31 (5,002 feet by 100 feet, concrete). The airport elevation was 962 feet mean sea level (msl). The elevation of the runway 31 threshold was 943 feet msl. A four-light precision approach path indicator (PAPI) was installed for runway 33. WRECKAGE AND IMPACT INFORMATION A postaccident investigation confirmed that all airframe structural and flight control components were located at the accident site. The main wreckage was located about 0.34 miles southeast of the runway 31 threshold and was facing a north-northwest heading. A ground depression consistent with an initial impact of the aft fuselage was located about 40 feet south-southeast of the main wreckage in a residential front yard. The ground depression continued on a north-northwest heading to where the airplane had impacted a brick wall of a residence. The main wreckage consisted of the entire airframe, flight controls, and engine. A fractured propeller blade was found underneath the aft fuselage. There were additional propeller blade fragments located along the wreckage debris path and in the back yard of the residence. All observed structural component failures were consistent with overstress separation. Flight control continuity was established between the individual flight control surfaces and their respective cockpit controls. The flap position could not be determined due to impact damage. The throttle and mixture controls were found in the full forward position. The carburetor heat control was found partially engaged. The magneto switch was found in the LEFT position. The fuel tank, located in the forward fuselage behind the instrument panel, was breached consistent with impact damage and contained residual fuel. The engine remained attached to the firewall. Internal engine and valve train continuity was confirmed as the engine crankshaft was rotated. Compression and suction were noted on all cylinders in conjunction with crankshaft rotation. The upper spark plugs were removed and exhibited features consistent with normal engine operation. Both magnetos provided spark on all leads when rotated. There were no obstructions between the air filter housing and the carburetor inlet. The fuel supply line to the carburetor and the carburetor bowl both contained fuel.A fuel sample was free of any water or particulate contamination. The carburetor inlet screen was free of any particulate contamination. Mechanical continuity was confirmed from the engine components to their respective cockpit engine controls. The postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. MEDICAL AND PATHOLOGICAL INFORMATION On June 30, 2011, autopsies were performed on the pilot and flight instructor at Sparrow Forensic Pathology Services located in Lansing, Michigan. The cause of death for the pilot and flight instructor was attributed to multiple injuries sustained during the accident. The FAA's Civil Aerospace Medical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on samples obtained during the pilot's autopsy. No carbon monoxide, cyanide, or ethanol was detected. Amlodipine was detected in urine and blood samples. Amlodipine is a long-acting calcium channel blocker used to lower blood pressure and to treat anginal chest pain. CAMI performed tests on samples obtained during the flight instructor's autopsy. No carbon monoxide or ethanol was detected. 0.6 ug/ml of cyanide was detected in blood samples. Alfuzosin was detected in blood and urine samples. Azacyclonol was detected in urine samples but not in blood samples. Dextromethorphan and dextrorphan were detected in urine and blood samples. Fexofenadine was detected in urine and blood samples. Naproxen was detected in urine samples. Rosuvastatin was detected in urine samples but not in blood samples. Alfuzosin, brand name Uroxatral, is a medication for benign prostatic hypertrophy and has minimal cardiovascular effects. Dextromethorphan, sold under multiple brand names, is a cough medication and is metabolized into dextrorphan. Fexofenadine, brand name Allegra, is a non-sedating antihistamine and is metabolized into azacyclonol. Naproxen, brand name Alleve, is a non-sedating analgesic. Rosuvastatin, brand name Crestor, is a medication to treat high cholesterol and prevent heart disease. SURVIVAL ASPECTS According to first responders, upon their arrival at the accident site, the pilot was not wearing his lap-belt or shoulder harness. The flight instructor was wearing both his lap-belt and shoulder harness. ## Aircraft - Registration: [N8AL](https://openairdocs.org/deregistered/N8AL-2011-10-19), registration cancelled 2011-10-19, S/N 238, built 1982 (OpenAirDocs) - Reported make and model: BOSONETTO THORP T-18 - Registry model: [Bosonetto Allen R. THORP T-18](https://openairdocs.org/model/bosonetto-allen-r-thorp-t-18) (registry code 89510F1) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 238 - Year built: 1982 - Airframe hours: 577 - Engines: Lycoming O-320-A1A 150 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, June 1, 2011, 6 hours before - Departed: 1D2, Plymouth, MI - Destination: OZW, Howell, MI - Airport: OZW, Livingston County Airport, runway 31, 5,002 × 100 ft, concrete - Equipment: Handheld GPS, Angle of attack indicator ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; injuries: fatal; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review April 5, 2009; seat: left; restraint: none; toxicology performed; flight hours: 166 total, 43 in this make and model - Flight instructor; age 70; injuries: fatal; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review July 1, 2010; seat: right; restraint: 3-point; toxicology performed; flight hours: 4,750 total, 0 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 300° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 46 °F - Altimeter: 30.05 inHg - Observed at: OZW ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20110629018199A](https://openairdocs.org/incident/20110629018199A), Jun 29, 2011: Bosonetto Allen R THORP T-18, Howell, MI, Destroyed, 2 fatal. Flight was for a regulatory flight review for PIC (his flight review expired in April 2011). Flight departed 1D2 at approximately 1830 local and proceeded to… ## Docket (16 files) The files NTSB released with the investigation on May 8, 2014, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=80942. 8.6 MB in all. - Witness Statements (item 1, .PDF, 433 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412093&FileExtension=.PDF&FileName=Witness%20Statements-Redacted.PDF - Accident Site Survey Plot (item 2, .PDF, 213 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412094&FileExtension=.PDF&FileName=Accident%20Site%20Survey%20Plot-Redacted.PDF - Pilot Logbook (Patrick Charles) (item 3, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412095&FileExtension=.PDF&FileName=Pilot%20Logbook%20(Patrick%20Charles)-Redacted.PDF - Flight Instructor Logbook (John Nowak) (item 4, .PDF, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412096&FileExtension=.PDF&FileName=Flight%20Instructor%20Logbook%20(John%20Nowak)-Redacted.PDF - Airframe Logbook (item 5, .PDF, 990 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412097&FileExtension=.PDF&FileName=Airframe%20Logbook-Redacted.PDF - Engine Logbook (item 6, .PDF, 820 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412098&FileExtension=.PDF&FileName=Engine%20Logbook-Redacted.PDF - FAA Inspector Statement Concerning Use of Seat Restraints (item 7, .PDF, 95 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412099&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement%20Concerning%20Use%20of%20Seat%20Restraints-Redacted.PDF - Toxicological Report (Patrick Charles) (item 8, .PDF, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412100&FileExtension=.PDF&FileName=Toxicological%20Report%20(Patrick%20Charles)-Master.PDF - Toxicological Report (John Nowak) (item 9, .PDF, 81 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412101&FileExtension=.PDF&FileName=Toxicological%20Report%20(John%20Nowak)-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 10, .PDF, 165 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412102&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.PDF - Photo 01 – Wreckage Debris Path (item 11, .PDF, 411 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412103&FileExtension=.PDF&FileName=Photo%2001%20%E2%80%93%20Wreckage%20Debris%20Path%0D%0A-Master.PDF - Photo 02 - Main Wreckage (Right Side) (item 12, .PDF, 435 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412104&FileExtension=.PDF&FileName=Photo%2002%20-%20Main%20Wreckage%20(Right%20Side)%0D%0A-Master.PDF - Photo 03 - Main Wreckage (Left Side) (item 13, .PDF, 387 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412105&FileExtension=.PDF&FileName=Photo%2003%20-%20Main%20Wreckage%20(Left%20Side)%0D%0A-Master.PDF - Photo 04 - Main Wreckage (Cabin) (item 14, .PDF, 389 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412107&FileExtension=.PDF&FileName=Photo%2004%20-%20Main%20Wreckage%20(Cabin)%0D%0A-Master.PDF - Photo 05 - Engine (Right Side) (item 15, .PDF, 279 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412108&FileExtension=.PDF&FileName=Photo%2005%20-%20Engine%20(Right%20Side)%0D%0A-Master.PDF - Photo 06 - Engine (Left Side) (item 16, .PDF, 267 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412109&FileExtension=.PDF&FileName=Photo%2006%20-%20Engine%20(Left%20Side)%0D%0A-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.