# NTSB FTW97LA004: PZL-Bielsko SZD-59, N597R, Sterling, CO, October 4, 1996 - Type: NTSB accident investigation - Classification: Accident · Fatal · Limited investigation · Final report - Date: October 4, 1996, 12:40 local (18:40 UTC) - Place: Sterling, CO - Coordinates: 40.620109, -103.189765 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.6201&lon=-103.1898&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report March 31, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 20080 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW97LA004 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/20080/pdf - Page: https://openairdocs.org/ntsb/FTW97LA004 ## Probable cause Loss of control when the pilot exceeded the velocity of stall while in a turn. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, approach - vfr pattern - downwind - airspeed(vs) - exceeded, pilot in command (cause) ## Analysis While returning to land after a practice aerobatics flight, the pilot flew the glider down the runway of intended landing at 100 feet above ground level and then entered a 45 degree bank left turn. The nose began to drop and the bank angle increased to about 60 degrees and the glider dove into the ground next to the runway with a nose attitude of approximately 60 degrees nose down. At the time, the glider tow plane was back taxiing on the runway. Terrain around the airport was flat grass covered farm fields. ## Factual narrative On October 4, 1996, at 1240 mountain daylight time, a PDPS PZL-Bielsko SZD-59 glider, N597R, impacted the ground after entering uncontrolled flight while in the traffic pattern at Sterling Municipal Airport, Sterling, Colorado. The commercial pilot received fatal injuries and the aircraft sustained substantial damage. Visual meteorological conditions prevailed for this local area personal flight operating under Title 14 CFR Part 91 and no flight plan was filed. The flight departed Sterling, approximately 20 minutes prior to the accident. According to witnesses, the pilot had been practicing in the aerobatics area and was in the process of returning to the airport for landing. An eyewitness said that the tow plane landed on runway 33 and began back taxiing. The glider then came down the runway about 100 feet above ground level, wings level, and entered a left turn at bout 45 degrees angle of bank. The witness said the nose began to drop and the bank angle increased to about 60 degrees. The glider then dove into the ground beside the runway at approximately 60 degrees nose down attitude. The witness said the glider came to rest in an upright position facing to the south. The terrain around the runway was flat grass covered farm fields. An examination of the glider by an FAA airworthiness inspector provided no evidence of preimpact failure or malfunction. According to the flight manual for the aircraft, the minimum speed marking on the airspeed indicator is 51 knots (59 mph). This speed is 1.1 X Vs (velocity of stall), wings level, at the maximum gross weight approved for aerobatics. Accelerometer limits are +7 and -5. Stall/spin recovery requires a maximum of 623 feet loss of altitude for recovery. ## Aircraft - Registration: [N597R](https://openairdocs.org/deregistered/N597R-2002-10-01), registration cancelled 2002-10-01, S/N B-2164, built 1995 (OpenAirDocs) - Reported make and model: PZL-Bielsko SZD-59 - Registry model: [Pdps Pzl-Bielsko SZD-59](https://openairdocs.org/model/pdps-pzl-bielsko-szd-59) (registry code 8821649) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Glider - Serial number: B-2164 - Engines: unknown - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Ruth A. Stevens - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, July 14, 1995 - Departed: STK - Airport: STK, Sterling Municipal, runway 33, 4,730 × 75 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: front; toxicology performed; flight hours: 665 total, 23 in this make and model, 543 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 350° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 50 °F - Altimeter: 30.00 inHg - Observed at: AKO, 34 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 19961004030899A](https://openairdocs.org/incident/19961004030899A), Oct 4, 1996: Sterling, CO, Substantial damage, 1 fatal 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.