# NTSB ATL97LA013: Let L-13, N15CB, Benton, TN, October 30, 1996 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: October 30, 1996, 18:00 local (23:00 UTC) - Place: Benton, TN - Coordinates: 35.16962, -84.649192 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.1696&lon=-84.6492&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor - Status: Completed, report August 21, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 3803 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL97LA013 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3803/pdf - Page: https://openairdocs.org/ntsb/ATL97LA013 ## Probable cause failure of the flight crew to maintain altitude/clearance above runway obstacles, and inadequate supervision by the flight instructor. Factors relating to the accident were sunglare on the canopy, and the proximity of obstacles (trees) to the runway. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, approach - vfr pattern - final approach - light condition - sunglare (contributing factor) - object - tree(s) (contributing factor) - altitude/clearance - not maintained, flightcrew (cause) - supervision - inadequate, pilot in command(cfi) (cause) ## Analysis The glider collided with a tree during final approach to landing on runway 21. According to the instructor and the student, they did not see the tree because of dusk lighting conditions, which placed the sun low on the horizon and produced glare on the glider canopy. The instructor stated that the tree was about 300 feet from the runway threshold. Runway obstacle information indicated that the threshold for the runway was displaced 200 feet. ## Factual narrative On October 30, 1996, about 1800 eastern standard time, a Let L-13 "Blanik" glider, N15CB, collided with trees during the final approach to the Chilhowee Glider Port, Benton, Tennessee. The glider was operated under the provisions of Title 14 CFR Part 91, and visual flight rules. A flight plan was not filed for the local instructional flight. There were serious injuries to the private pilot under instruction, minor injuries to the airline transport instructor, and substantial damage to the glider. Origination of the flight was Benton, Tennessee, about 1730 on the same day. The instructor stated that when the glider was turned onto the final approach for landing on runway 21, the sun was directly in their eyes. He stated that the glare on the canopy was causing very poor visibility. He was able to barely see the runway directly in front of the aircraft and side visibility was nil. The pilot under instruction continued the final approach descent and collided with a tree short of the runway. Both pilots stated they did not see the tree until the collision occurred. The instructor indicated in his report of the accident that the tree was about 300 feet from the end of the runway. Airport information obtained from an Internet file entitled "Airnav" regarding the airport indicated that the runway 21 threshold is displaced 200 feet. A 36 foot tree is listed as an obstacle, located 500 feet from the threshold and 110 feet right of the centerline. The slope to clear the tree is listed as 13:1. ## Aircraft - Registration: [N15CB](https://openairdocs.org/deregistered/N15CB-2013-08-06), registration cancelled 2013-08-06, S/N 174806, built 1971 (OpenAirDocs) - Reported make and model: Let 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: 174806 - Engines: unknown - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Wendylene, Inc - Registered owner: Earl D.Masters/James E. Davis - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 21, 1996, 12 hours before - Departed: 92A - Airport: 92A, Chillhowee Glider Port, runway 21, 2,600 × 200 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 31; airline transport; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: rear; flight hours: 7,500 total, 7 in this make and model, 5,500 as pilot in command, 200 in the last 90 days, 80 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dusk - Wind: 270° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F ## 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 19961030037039A](https://openairdocs.org/incident/19961030037039A), Oct 30, 1996: Let L13BLANIK, Benton, TN, Substantial damage. Collided with a tree on short final. CFI and student reported blinded by sun. Displaced thresold not considered. (-23) instructor allowed student to descend… ## Other investigations on N15CB (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 MIA75DKT14](https://openairdocs.org/ntsb/MIA75DKT14), Sep 15, 1974: Let-Np-K L-13 (N15CB), Boca Raton, FL, substantial damage 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.