# NTSB LAX01LA211: Hughes 369HS, N4467V, Mountain View, CA, June 16, 2001 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: June 16, 2001, 14:15 local (21:15 UTC) - Place: Mountain View, CA - Coordinates: 37.428333, -122.024444 - Nearby events: https://openairdocs.org/map.md?lat=37.4283&lon=-122.0244&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor - Status: Completed, report October 24, 2002 - Report: Approved by Office Director - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 52515 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX01LA211 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/52515/pdf - Page: https://openairdocs.org/ntsb/LAX01LA211 ## Probable cause The pilot's failure to maintain control while hovering out of ground effect. A factor was the wind gusts. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, hover - out of ground effect - object - tower(marked) - weather condition - sudden windshift (cause) - aircraft control - not maintained, pilot in command (cause) - dynamic rollover - uncontrolled, pilot in command - weather condition - gusts (cause) - In flight collision with terrain/water, descent - uncontrolled ## Analysis During powerline maintenance work, the pilot lost control of the helicopter, resulting in the main rotor blades contacting a transmission line tower, and the helicopter fell to the ground. As he had on numerous occasions, the pilot flew to the tower to pickup a passenger who was performing maintenance on it. The pilot placed one of the helicopter's skids on the tower and the passenger began boarding. However, on this occasion a gust of wind was experienced and the wind direction suddenly shifted. Despite the pilot's effort to maintain control, the helicopter dynamically rolled over resulting in a main rotor blade striking the tower. Thereafter, the pilot lost total control and the helicopter fell about 90 feet to the ground. No mechanical malfunctions were reported. ## Factual narrative On June 16, 2001, about 1415 hours Pacific daylight time, a Hughes 369HS, N4467V, collided with a tower and crashed about 1.5 miles northeast of Moffett Field, Mountain View, California. The helicopter was operated by Trinity Helicopters, Inc., Hayward, California. Visual meteorological conditions prevailed at the time of the public utility work-related flight performed under 14 CFR Part 133. No flight plan was filed. The helicopter was destroyed. The commercial pilot was seriously injured, and the passenger received minor injuries. The flight originated from Mountain View about 1410. According to the pilot, he flew to the tower to pickup a passenger who was performing maintenance on the tower. The pilot placed one skid on the tower and the passenger began boarding the helicopter. Although he had performed this type of maneuver on numerous occasions, on this occasion the wind direction suddenly shifted from a direct tail wind to a right crosswind. Despite his effort to maintain control, the helicopter dynamically rolled over resulting in a main rotor blade striking the tower. Control was lost, and the helicopter fell about 90 feet to the ground. The pilot also indicated that prior to experiencing the loss of control, no mechanical malfunctions were experienced. The pilot further indicated that the sudden change in the wind direction was not predictable. The pilot estimated that, at the time of the mishap, the wind was from the northwest at 10 knots. There were gusts to 15 knots. ## Aircraft - Registration: [N4467V](https://openairdocs.org/aircraft/N4467V), registered now, S/N 120363S (OpenAirDocs) - Reported make and model: Hughes 369HS - Registry model: [Hughes 369HS](https://openairdocs.org/model/hughes-369hs) (registry code 4470728) (OpenAirDocs) - Category: Helicopter - Serial number: 12063635 - Airframe hours: 7635 - Engines: Allison 250-C20 375 horsepower turbo shaft - Damage: Destroyed - Flight: Other work use, Part 133 - Registered owner: Trinity Helicopters, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, May 24, 2001, 6 hours before - Departed: NUQ, MOUNTAIN VIEW, CA - Destination: Mountain View, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 26; injuries: serious; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: helicopter, airplane; medical: class 2, without waivers/limitations; last flight review January 30, 2001; seat: left; flight hours: 2,961 total, 1,922 in this make and model, 2,223 as pilot in command, 105 in the last 90 days, 70 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 52 °F - Altimeter: 29.94 inHg - Observed at: NUQ, 2 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 20010616014359A](https://openairdocs.org/incident/20010616014359A), Jun 16, 2001: Hughes 369HS, Mountain View, CA, No damage. (.19)On June 16, 2001, about 1415 hours pacific daylight time, a Hughes 369HS, N4467V, operated by trinity helicopters, inc., hayward, California, collided… 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.