# NTSB DEN99LA111: Piper PA-18-150, N4785F, Boulder, CO, July 1, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 1, 1999, 15:15 local (21:15 UTC) - Place: Boulder, CO - Coordinates: 40.019557, -105.250259 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.0196&lon=-105.2503&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report October 13, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46700 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN99LA111 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46700/pdf - Page: https://openairdocs.org/ntsb/DEN99LA111 ## Probable cause The pilot's failure to maintain control of the aircraft during landing roll. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Nose over, landing - roll - aircraft control - not maintained, pilot in command (cause) ## Analysis The pilot departed the airport with a glider in tow. After the glider was released, she returned for landing. She made a 'smooth wheel landing with no bounces,' and the aircraft rolled 'straight and smoothly' on the two main wheels. She felt the tail of the airplane begin to rise, and she pulled back on the stick, but stated that she was unable to get a response from the elevator. The aircraft continued to roll forward until the spinner impacted the pavement. The airplane then nosed over onto its back. The wind was calm during landing. In a telephone interview with the pilot shortly after the accident, she stated that the aircraft's wheels touched down twice on the runway prior to the third actual touchdown. Following the accident, a functional test of the elevator control system was performed. The elevator operated effectively, and no abnormalities or discrepancies were observed. ## Factual narrative On July 1, 1999, approximately 1515 mountain daylight time, a Piper PA-18-150, N4785F, owned and operated by the Soaring Society of Boulder, was substantially damaged when the aircraft nosed over during landing roll at Boulder Municipal Airport, Boulder, Colorado. The private pilot, the sole occupant aboard, was not injured. The local glider tow flight was being conducted under Title 14 CFR Part 91, and no flight plan had been filed. The flight originated approximately 15 minutes prior to the accident, and visual meteorological conditions prevailed. According to the pilot, she departed the airport with a glider in tow. After the glider was released, she returned to the airport for landing. The pilot stated that the wind was calm during landing. She made a "smooth wheel landing with no bounces," and the aircraft rolled "straight and smoothly" on the two main wheels (in a telephone interview with the pilot shortly after the accident, she stated that the aircraft's wheels touched down twice on the runway prior to the third actual touchdown.) She felt the tail of the airplane begin to rise, and she pulled back on the stick. She stated that there was no response from the elevator, and the aircraft continued to roll forward slowly until the spinner impacted the pavement. The airplane then nosed over onto its back. The aircraft sustained damage to the propeller, firewall, vertical stabilizer, and both wing spars. At the NTSB's request, a functional test of the elevator control system was performed by a mechanic with Jensen Aircraft, Salida, Colorado. The elevator operated effectively, and no abnormalities or discrepancies were found. ## Aircraft - Registration: [N4785F](https://openairdocs.org/aircraft/N4785F), registered now, S/N 18-7906, built 1962 (OpenAirDocs) - Reported make and model: Piper PA-18-150 - Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-7906 - Airframe hours: 12125 - Engines: Lycoming O-360-A3A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Part 91 - Registered owner: Soaring Society Of Boulder - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 16, 1999, 158 hours before - Departed: 1V5 - Airport: 1V5, Boulder Municipal Airport, runway 8, 4,100 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: front; flight hours: 546 total, 43 in this make and model, 430 as pilot in command, 16 in the last 90 days, 11 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 4 knots - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 88 °F, dew point 55 °F - Altimeter: 29.00 inHg - Observed at: BJC, 9 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 19990701007999A](https://openairdocs.org/incident/19990701007999A), Jul 1, 1999: Piper PA18150, Boulder, CO, Substantial damage. Acft flipped over on landing, other circumstances are unknown. (-23)no narrative ## Other investigations on N4785F (3) 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 GAA19CA572](https://openairdocs.org/ntsb/GAA19CA572), Sep 23, 2019: Piper PA18 (N4785F), Boulder, CO, substantial damage. Probable cause: The pilot's failure to maintain directional control during the landing roll, which resulted in a ground loop. - [NTSB GAA15CA011](https://openairdocs.org/ntsb/GAA15CA011), Mar 16, 2015: Piper PA18 - 150 (N4785F), Boulder, CO, substantial damage. Probable cause: The pilot's loss of directional control during a bounced landing, which resulted in a runway excursion. - [NTSB DEN00LA126](https://openairdocs.org/ntsb/DEN00LA126), Jul 8, 2000: Piper PA-18-150 (N4785F), Erie, CO, substantial damage. Probable cause: Aircraft control was not possible by the flight instructor due to the inadequate maintenance adjustment of the tail wheel steering system by maintenance personnel. Factors were the inadequate… 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.