# NTSB CHI01LA277: Blanik L-13, N9297Z, Marlette, MI, August 4, 2001 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 4, 2001, 15:00 local (19:00 UTC) - Place: Marlette, MI - Coordinates: 43.319549, -83.080833 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.3195&lon=-83.0808&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 uninjured - Status: Completed, report November 28, 2001 - Report: Approved by Office Director - Parties: FAA - NTSB case key (mKey): 53015 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI01LA277 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/53015/pdf - Page: https://openairdocs.org/ntsb/CHI01LA277 ## Probable cause Ground crew personnel improperly connected the tow winch cable prior to takeoff which resulted in one side of the winch cable coming disconnected. Factors associated with the accident were the ditch and the tree branch which the airplane contacted. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, takeoff - roll/run - glider/tow/launch equipment - improper, other person (cause) - glider launch/tow equipment - disconnected (cause) - remedial action - attempted, pilot in command(cfi) - On ground/water encounter with terrain/water, takeoff - roll/run - terrain condition - ditch (contributing factor) - On ground/water collision with object, takeoff - roll/run - object - tree(s) (contributing factor) ## Analysis The CFI reported that during the takeoff the left hook of the winch harness released, uncommanded, from the center of gravity attachment. The glider yawed to the left toward a ditch on the west side of the runway. The CFI applied right aileron and full right rudder in an attempt to avoid the ditch however the glider continued into the ditch. The glider came to rest bridging the ditch on a heading of east. He reported that the ditch was full of broken and cut down brush and saplings. During the impact, a broken branch penetrated the left side of the cockpit and impaled itself in the CFI's right calf. The CFI remained hospitalized for five days following the accident. Members of the glider club reported that they had hooked both the left and right side cables prior to the takeoff. Inspection of the tow winch failed to reveal any mechanical failure/malfunction. ## Factual narrative On August 4, 2001, at 1500 eastern daylight time, a Blanik L-13 glider, N9297Z, collided with a tree during an initial takeoff run at the Marlette Township Airport, Marlette, Michigan. The certified flight instructor (CFI) received a serious injury and the student pilot was not injured. The glider received minor damage. The 14 CFR Part 91 instructional flight was operating in visual meteorological conditions without a flight plan. The local flight was originating when the accident occurred. The CFI reported, "The slack out - go - signal was given from the operations trailer and take-off power was applied to the winch, whereupon the left hook of the winch harness released, uncommanded, from the center of gravity attachment. The uneven force caused the glider to yaw to the left and head for the ditch on the west side of the runway. I applied right aileron and full right rudder, but was unable to keep the glider from floating into the ditch." The CFI reported the glider ended up bridging the ditch on a heading of east. He reported that the ditch was full of broken and cut down brush and saplings. During the impact, a broken branch penetrated the left side of the cockpit and impaled itself in the CFI's right calf. The CFI remained hospitalized for five days following the accident. Members of the glider club reported that they had hooked both the left and right side cables prior to the takeoff. Inspection of the tow winch by an inspector from the Federal Aviation Administration Detroit Flight Standards District Office failed to reveal any mechanical failure/malfunction. ## Aircraft - Registration: [N9297Z](https://openairdocs.org/deregistered/N9297Z-2004-03-31), registration cancelled 2004-03-31, S/N 026505, built 1975 (OpenAirDocs) - Reported make and model: Blanik L-13 - Registry model: [Let BLANIK L-13](https://openairdocs.org/model/let-blanik-l-13) (registry code 1360306) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: 026505 - Airframe hours: 1314 - Damage: Minor damage - Flight: Instructional, Part 91 - Operator: Peter Sisoy - Registered owner: Vultures Soaring Club - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 13, 2001, 17 hours before - Departed: 77G, Marlette, MI - Destination: Marlette, MI - Airport: 77G, Marlette Township, runway 01, 3,500 × 75 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 79; injuries: serious; flight instructor; seat: rear; flight hours: 800 total, 800 as pilot in command, 16 in the last 90 days, 2 in the last 30 days, 1 in the last 24 hours - Student pilot; injuries: none - Student pilot; age 14; injuries: none; student; seat: front ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 88 °F, dew point 55 °F - Altimeter: 30.04 inHg - Observed at: FNT, 40 nm away ## 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 20010804026139A](https://openairdocs.org/incident/20010804026139A), Aug 4, 2001: Marlette, MI, No damage. (.19) On August 4, 2001, at 1515 eastern daylight time, a blanik L-13 glider, N9297Z, collided with a tree during an initial takeoff run at the Marlette… ## Other investigations on N9297Z (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 CHI90LA140](https://openairdocs.org/ntsb/CHI90LA140), May 26, 1990: Let L-13 (N9297Z), Oxford, MI, substantial damage. Probable cause: THE GLIDER PILOT'S FAILURE TO MAINTAIN ADEQUATE AIRCRAFT CONTROL DURING THE TOUCHDOWN AND LANDING ROLL. THE POORLY EXECUTED APPROACH TO LANDING, AND ROUGH/UNEVEN TERRAIN WERE CONTRIBUTING FACTORS IN… 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.