# NTSB ERA22FA137: Beech 35, N6129V, Hilltown Township, PA, February 24, 2022 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 3 · Field · Final report - Date: February 24, 2022, 16:56 local (21:56 UTC) - Place: Hilltown Township, PA · Intersection of Victoria Lane & Brittany Lane in Hilltown Township, PA - Coordinates: 40.347778, -75.278889 - Nearby events: https://openairdocs.org/map.md?lat=40.3478&lon=-75.2789&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: Textron, FAA - NTSB case key (mKey): 104702 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA22FA137 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/104702/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=104702 - Page: https://openairdocs.org/ntsb/ERA22FA137 ## Probable cause The pilots’ exceedance of the airplane’s critical angle of attack while practicing maneuvers during an instructional flight, which resulted in an aerodynamic stall and and a loss of airplane control. ## 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 · Flight crew (probable cause); cases with it: [Beech 35-C33, 5 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1151408), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [Beech 35-C33, 1 case](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=1151408), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Beech 35-C33, 3 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=1151408), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Maneuvering: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241); cases with it: [Beech 35-C33, 1 case](https://openairdocs.org/ntsb-events/241/sequence.md?model=1151408), [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: [Beech 35-C33, 5 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1151408), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The flight instructor and the pilot receiving instruction were conducting a flight in an airplane that the pilot receiving instruction owned, and the purpose of the accident flight was to prepare him for the commercial pilot practical examination. About 30 minutes after takeoff, the airplane was maneuvering at an altitude of about 1,600 ft above ground level. The airplane then entered a left spin and descended toward the ground, impacting a residential street. A witness stated that he heard a single engine airplane overhead and thought the airplane’s loud engine sound did not match its slow airspeed, which meant to him that the airplane was most likely in a steep climb to practice a stall. The witness looked up again and saw the airplane diving almost straight down and twisting toward the ground. Examination of the wreckage revealed no preimpact mechanical malfunctions. Review of automatic dependent surveillance-broadcast (ADS-B) data revealed that the airplane’s maneuvers during the final portion of flight were conducted below its flaps-up, idle power stall speed and were twice briefly below the flaps-down stall speed. During the final 30 seconds of flight, the airplane rolled rapidly to the left when engine noise was reduced. The airplane’s rapid left roll and loss of altitude were consistent with an aerodynamic stall. Thus, the pilot who was flying (which could not be determined based on the available evidence) allowed the airplane’s critical angle of attack to be exceeded, resulting in a loss of airplane control. Toxicological testing detected ethanol and metoprolol in the flight instructor’s specimens. The most likely source of the ethanol was postmortem production; therefore, the identified ethanol did not contribute to the circumstances of the accident. Although direct effects from the flight instructor’s use of metoprolol likely did not contribute to the events, the available evidence precluded a determination of whether effects from the flight instructor’s recent heart attack and underlying heart disease contributed to the circumstances of the accident. In addition, if the flight instructor had experienced a medical event during the flight, should have been reasonable able to control the airplane. ## Factual narrative Video Study The National Transportation Safety Board (NTSB) conducted a video study to estimate the speed of the airplane’s engine based on a video recorded by a camera installed on a residential building. The video was 65 seconds long and included sound. The study found that the engine was operating erratically near its expected operating speed—about 2,600 rpm. The last 11 seconds before ground impact included a 3-second period during which there was likely no combustion or the engine was idling. The airplane’s rapid descent toward the ground started about the same time as this 3-second period. Aircraft Performance Study The NTSB also conducted a performance study for the accident flight. ADS-B data showed that the airplane’s altitude varied between 1,400 and 4,000 ft mean sea level and that the calibrated airspeed varied between 50 and 150 knots. The study found that the airplane’s maneuvers during the final portion of flight were below its flaps-up, idle power stall speed and were twice briefly below the flaps-down stall speed. The performance study also used images toward the end of the flight from the video recording to correlate the video data with the flightpath data. The study found that, during the final 30 seconds of flight, the airplane rolled left when engine noise was reduced. On February 24, 2022, about 1656 eastern standard time, a Beech 35-C33, N6129V, was destroyed when it was involved in an accident near Hilltown Township, Pennsylvania. The flight instructor and the pilot receiving instruction were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The pilot receiving instruction owned the airplane and had successfully completed the commercial pilot written examination. The purpose of the accident flight was to prepare him for the commercial pilot practical examination. Review of Automatic Dependent Surveillance-Broadcast (ADS-B) data revealed that the airplane departed Doylestown Airport (DYL), Doylestown, Pennsylvania, about 1626. The data also showed that the airplane, while maneuvering at an altitude of about 2,000 ft mean sea level (about 1,600 ft above ground level), the airplane began to descend. A witness to the accident was a licensed private pilot who tended to look up at the sky as small airplanes flew over. When the witness was standing in his neighbor’s driveway, he heard a single-engine airplane overhead and thought the airplane’s engine was loud and the airspeed was slow, which indicated to him that the airplane was most likely in a steep climb to practice a stall. By the time that he looked up at the sky again, he saw the airplane “diving, almost straight down” and “twisting toward the ground.” The airplane was out of the witness’ view after it descended behind a tree line. The witness then saw “a black ball of smoke.” The airplane impacted a residential street. During the impact, a propeller blade separated and landed in a residence. The wreckagecame to rest upright, oriented about 125° magnetic and no debris path was observed. A postimpact fire consumed most of the wreckage. The Bucks County Coroner’s Office, Warminster, Pennsylvania, performed autopsies for both the pilot receiving instruction and the flight instructor by. Their cause of death was multiple blunt force injuries. The flight instructor had a heart attack about 3 weeks before the accident. The autopsy examination of his heart was limited by the extent of his injuries. Toxicology testing was performed on the pilot receiving instruction and flight instructor by the FAA Forensic Sciences Laboratory. The testing was negative for the pilot receiving instruction. The testing for the flight instructor identified ethanol in liver tissue but not in his muscle tissue. The testing also identified metoprolol in both tissues. Ethanol is primarily a social drug found in beer, wine, and liquor and is a central nervous system depressant. Ethanol can also be produced by body tissues after death. Metoprolol is a beta-blocking drug used to treat high blood pressure, control heart rate, and prevent recurrent heart attacks. The drug is generally considered not to be impairing. The pilot’s logbook was not recovered. On an application for his commercial pilot certificate, dated February 15, 2022, he reported a total flight experience of 733 hours. During a previous insurance renewal quote for the accident airplane, he reported 385 hours of flight experience in the make and model airplane. Review of the flight instructor’s logbook revealed that he had a total flight experience of approximately 11,500 hours; of which, 8,000 hours were providing flight instruction. The wreckage came to rest upright on a magnetic heading of about 125°, and no debris path was observed. The cockpit and cabin were mostly consumed by fire. Both wings separated from the airplane, but their respective flaps and ailerons remained attached. The empennage remained intact with the rudder and elevator still attached. The flaps and landing gear were retracted. Flight control continuity was confirmed from all flight control surfaces to the cockpit area. Measurement of the two elevator trim actuators corresponded to a 5° trim-tab-down (nose-up) position. The engine came to rest upright separate from the airframe. The three propeller blades separated from the hub. One blade was consumed by fire about 12 inches outboard of the root. Another blade exhibited fire damage, s-bending, chordwise scratching, and leading-edge gouging. The other propeller blade exhibited s-bending, chordwise scratching, and leading-edge gouging. ## Aircraft - Registration: [N6129V](https://openairdocs.org/aircraft/N6129V), registered now, S/N CD-858, built 1965 (OpenAirDocs) - Reported make and model: BEECH 35 (C33) - Registry model: [Beech 35-C33](https://openairdocs.org/model/beech-35-c33) (registry code 1151408) (OpenAirDocs) - Registry engine: [Continental I0-470 series](https://openairdocs.org/engine/continental-i0-470-series) (registry code 17027, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: CD-858 - Year built: 1965 - Airframe hours: 6782 - Engines: Continental IO-520-BA 285 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 5, 2021 - Departed: DYL, Doylestown, PA - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: fatal; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review April 13, 2019; seat: left; toxicology performed; flight hours: 733 total, 385 in this make and model - Flight instructor; age 74; injuries: fatal; airline transport, commercial, flight instructor, private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; seat: right; toxicology performed; flight hours: 11,500 total ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: 3,900 ft overcast - Temperature: 34 °F, dew point 16 °F - Altimeter: 30.39 inHg - Observed at: KDYL, 7 nm away - METAR: KDYL 242154Z AUTO 00000KT 10SM OVC039 01/M09 A3039 ## 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 20220224004209A](https://openairdocs.org/incident/20220224004209A), Feb 24, 2022: Beech 35-C33, Perkasie, PA, Destroyed, 2 fatal. Video footage obtained from the doylestown airport maintenance camera (kdyl), shows N6129V landing at 16:21:22 EST on runway 5. At 16:23:13 EST, the kdyl… ## Other investigations on N6129V (1) 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. - [NTSB NYC68F0283](https://openairdocs.org/ntsb/NYC68F0283), Oct 9, 1967: Beech 35-C33 (N6129V), Niagara Falls, NY, substantial damage ## Docket (15 files) The files NTSB released with the investigation on September 20, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=104702. 13.3 MB in all. - Witness statement (item 1, PDF, 1 page, 157 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14481517&FileExtension=pdf&FileName=Witness%20Statement_Redacted-Rel.pdf - Interview summary (item 2, PDF, 1 page, 105 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462324&FileExtension=pdf&FileName=Interview%20Summary-Rel.pdf - Fuel receipt (item 3, PDF, 1 page, 65 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462334&FileExtension=pdf&FileName=N6129V%20Fuel%20Receipt%2002202022-Rel.pdf - Excerpt from pilot application for airman certificate (flight experience) (item 4, PDF, 1 page, 593 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14461809&FileExtension=pdf&FileName=8710%20Excerpt_Redacted-Rel.pdf - Pilot flight experience reported to insurance company (item 5, PDF, 1 page, 328 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462476&FileExtension=pdf&FileName=Pilot%20Insurance%20Application%20Flight%20Hours_Redacted-Rel.pdf - Excerpts from flight instructor logbook (item 6, PDF, 2 pages, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14461549&FileExtension=pdf&FileName=CFI%20Logbook%20Excerpts-Rel.pdf - Excerpts from maintenance logbooks (item 7, PDF, 12 pages, 3.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462634&FileExtension=pdf&FileName=Mx%20Excerpts_Redacted-Rel.pdf - Wreckage examination (item 8, PDF, 3 pages, 377 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462644&FileExtension=pdf&FileName=Wreckage%20Examination-Rel.pdf - Photo array (item 9, PDF, 4 pages, 811 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14481432&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf - Toxicological reports (item 10, PDF, 2 pages, 306 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462058&FileExtension=pdf&FileName=Tox%20Reports_Redacted-Rel.pdf - Medical factual report (item 11, PDF, 3 pages, 133 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13858318&FileExtension=pdf&FileName=ERA22FA137_Medical%20Factual%20Report-Rel.pdf - Video study (item 12, PDF, 7 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14483480&FileExtension=pdf&FileName=Hilltown_Video_Study_final-Rel.pdf - Aircraft performance study (item 13, PDF, 7 pages, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14258273&FileExtension=pdf&FileName=ERA22FA137_PerformanceStudy-Rel.pdf - Statement of party representatives to NTSB investigation (item 14, PDF, 9 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462398&FileExtension=pdf&FileName=Party%20Form_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 15, PDF, 1 page, 467 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14462654&FileExtension=pdf&FileName=Wreckage%20Release_Redacted-Rel.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.