# NTSB LAX99LA170: Wsk Pzl Warzawa-Okecie PZL-104 Wilga 80, N4UU, Reno, NV, May 6, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 6, 1999, 10:30 local (17:30 UTC) - Place: Reno, NV - Coordinates: 39.479663, -119.739807 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.4797&lon=-119.7398&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report November 22, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46261 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX99LA170 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46261/pdf - Page: https://openairdocs.org/ntsb/LAX99LA170 ## Probable cause The flight instructor's improper supervision of the pilot trainee and his failure to make timely control inputs in order to maintain aircraft control. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, landing - roll - weather condition - tailwind - rudder - improper use of, dual student - remedial action - delayed, pilot in command(cfi) (cause) - supervision - inadequate, pilot in command(cfi) (cause) - ground loop/swerve - encountered - Nose over, landing - roll ## Analysis The flight instructor reported that they were landing on runway 26 and the aircraft touched down on the runway centerline with a slight crab to the left. The flight instructor stated that the pilot trainee 'overcorrected with right rudder input causing a swerve to the right.' The pilot trainee applied left rudder but the aircraft continued to veer to the right. The flight instructor reported that he took the flight controls in an effort to correct the drift, but realized that the 'swerve had become uncontrollable.' He stated that he felt it was too late to recover by applying engine power, so he began to apply control inputs for a ground loop. As the aircraft began to ground loop, the left wing contacted the runway surface. The flight instructor reported that the tail of the aircraft began to rise, and the combination of a slight tail wind, a left wing heavy fuel load, and possible excessive braking resulted in the aircraft pitching over and coming to rest inverted on the runway. The flight instructor reported that the automated weather observation service (AWOS) at the airport indicated that the winds were from the east at 4 knots at the time of the accident. ## Factual narrative On May 6, 1999, at 1030 hours Pacific daylight time, a WSK-PZL Warzawa-Okecie PZL-104 Wilga 80, N4UU, (a Polish manufactured airplane), ground looped while landing at the Reno-Stead Airport, Reno, Nevada. The experimental aircraft, owned and operated by the private pilot, sustained substantial damage. Neither the airline transport licensed flight instructor nor the private pilot trainee were injured. The local area instructional flight was conducted under the provisions of 14 CFR Part 91 and originated about 0830 from the Reno-Stead Airport. Visual meteorological conditions prevailed and no flight plan was filed. The flight instructor reported that they were landing on runway 26 and the aircraft touched down on the runway centerline with a slight crab to the left. The flight instructor stated that the pilot trainee "overcorrected with right rudder input causing a swerve to the right." The pilot trainee applied left rudder but the aircraft continued to veer to the right. The flight instructor reported that he took the flight controls in an effort to correct the drift, but realized that the "swerve had become uncontrollable." He stated that he felt it was too late to recover by applying engine power, so he began to apply control inputs for a ground loop. As the aircraft began to ground loop, the left wing contacted the runway surface. The flight instructor reported that the tail of the aircraft began to rise, and "the combination of a slight tail wind, approximately 8 gallon fuel imbalance (left wing heavy), and possible excessive braking resulted in the aircraft pitching over and coming to rest inverted on the runway." The flight instructor reported that the automated weather observation service (AWOS) at the airport indicated that the winds were from the east at 4 knots at the time of the accident. ## Aircraft - Registration: [N4UU](https://openairdocs.org/aircraft/N4UU), registered now, S/N CF21910927, built 1991 (OpenAirDocs) - Reported make and model: Wsk Pzl Warzawa-Okecie PZL-104 WILGA 80 (PZL-104 WI) - Registry model: [Wsk-Pzl Warzawa-Okecie PZL-104 WILGA 80](https://openairdocs.org/model/wsk-pzl-warzawa-okecie-pzl-104-wilga-80) (registry code 9810280) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane - Serial number: CF21910927 - Airframe hours: 459 - Engines: Pzl-Kalisz AI-14KA 262 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Thomas Irwin - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, July 12, 1998, 67 hours before - Departed: 4SD - Airport: 4SD, Reno-Stead, runway 26, 7,600 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; flight instructor, airline transport, commercial; airplane ratings: single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 7,093 total, 33 in this make and model, 5,835 as pilot in command, 10 in the last 90 days, 5 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 64 °F, dew point 27 °F - Altimeter: 30.00 inHg - Observed at: RNO, 12 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 19990506004669A](https://openairdocs.org/incident/19990506004669A), May 6, 1999: Wsk PZL104, Reno, NV, Substantial damage. Acft ground looped on landing. (From .19) on may 6, 1999, at 1030 hours pacific daylight time, a Wsk-pzl warzawa-okecie PZL-104 wilga 80, N4UU, (a polish… 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.