# NTSB LAX99LA041: Boeing A75N1, N59734, Vacaville, CA, November 25, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 25, 1998, 13:30 local (21:30 UTC) - Place: Vacaville, CA - Coordinates: 38.409748, -122.010025 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.4097&lon=-122.0100&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 31, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 45372 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX99LA041 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45372/pdf - Page: https://openairdocs.org/ntsb/LAX99LA041 ## Probable cause The pilot's inadequate compensation for the existing variable wind conditions and his failure to maintain directional 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 - flare/touchdown - weather condition - tailwind (contributing factor) - compensation for wind conditions - inadequate, pilot in command (cause) - directional control - not maintained, pilot in command (cause) - ground loop/swerve - inadvertent, pilot in command - Nose over, landing - roll - terrain condition - soft ## Analysis The aircraft ground looped and nosed over during landing. The pilot had monitored the Automated Surface Observation System prior to landing, which reported variable winds at 4 to 5 knots. There were two other aircraft in the traffic pattern, and they used the same runway. The pilot said he did not notice that the winds had changed to a slight tailwind, and on touchdown, he lost directional control and the left wing touched the runway. The aircraft then turned sharply off the runway, encountered soft mud, and nosed over. There were no discrepancies found with the aircraft. ## Factual narrative On November 25, 1998, at 1330 hours Pacific standard time, a Boeing A75N1, N59734, ground looped and nosed over during landing at the Vacaville, California, airport. The aircraft was owned and operated by the pilot under 14 CFR Part 91, and was on a personal flight from Executive Airport, Sacramento, California. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft sustained substantial wing damage. The private pilot, the sole occupant, was not injured. In a written statement, the pilot reported he had his landing gear serviced in Sacramento, and was returning back to Vacaville. Prior to his arrival in Vacaville, he monitored the ASOS, which reported winds as variable at 4 to 5 knots. There were two other aircraft in the traffic pattern, and they were using runway 02. The pilot said he did not notice that the winds had changed to a slight tailwind, and on touchdown, he lost directional control and the left wing touched the runway. The aircraft then turned sharply off the runway, encountered soft mud, and nosed over. The pilot stated that there were no mechanical discrepancies with the aircraft. The pilot went on to state that a few pilots had commented on the unreliability of the ASOS located on the field. In a telephone interview with the airport manager of Nut Tree Airport, Vacaville, he stated that the ASOS is located in an open field, and there are no restrictions to the sensors. He said that pilots have not complained about the ASOS, but have commented on how accurate and reliable it is. The ASOS is Federal Aviation Administration approved, and it is the only certified ASOS in the county. ## Aircraft - Registration: [N59734](https://openairdocs.org/deregistered/N59734-2005-04-11), registration cancelled 2005-04-11, S/N 75-3160, built 1941 (OpenAirDocs) - Reported make and model: Boeing A75N1 - Registry model: [Boeing A75N1(PT17)](https://openairdocs.org/model/boeing-a75n1-pt17) (registry code 1380134) (OpenAirDocs) - Registry engine: [Continental R670-SERIES series](https://openairdocs.org/engine/continental-r670-series-series) (registry code 17016, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 75-3160 - Airframe hours: 978 - Engines: Continental R670 220 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: William E. Mcnulty - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 15, 1998, 6 hours before - Departed: SAC, SACRAMENTO, CA - Airport: O45, Nut Tree, runway 2, 3,800 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; private; airplane ratings: multi-engine land, single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: rear; flight hours: 315 total, 87 in this make and model, 178 as pilot in command, 41 in the last 90 days, 10 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 63 °F, dew point 45 °F - Altimeter: 30.00 inHg - Observed at: SAC, 30 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 19981125046049A](https://openairdocs.org/incident/19981125046049A), Nov 25, 1998: Boeing A75N1, Vacaville, CA, Substantial damage. (.4) The aircraft ground looped and nosed over during landing. The pilot had monitored ASOS prior to landing, which reported variable winds at 4 to 5 knots.… 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.