# NTSB LAX99TA115: McDonnell Douglas 600N, N626SB, Rialto, CA, March 10, 1999 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Final report - Date: March 9, 1999, 17:55 local (Mar 10, 1999, 01:55 UTC) - Place: Rialto, CA - Coordinates: 34.100776, -117.380821 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.1008&lon=-117.3808&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 3 minor - Status: Completed, report January 18, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 45899 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX99TA115 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45899/pdf - Page: https://openairdocs.org/ntsb/LAX99TA115 ## Probable cause The pilot's improper in-flight decision to maneuver in the area while observed inclement weather approached, which led to a loss of control. Contributing factors were the low ceilings, mountainous terrain and spatial disorientation. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, maneuvering - weather condition - low ceiling (contributing factor) - terrain condition - mountainous/hilly - in-flight planning/decision - improper, pilot in command (cause) - flight into known adverse weather - inadvertent, pilot in command (cause) - aircraft control - not maintained, pilot in command (cause) - spatial disorientation, pilot in command (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - mountainous/hilly (contributing factor) ## Analysis During a routine law enforcement patrol flight, the pilot responded to the 4,700-foot mean sea level mountainside to investigate circumstances related to an apparent abandoned vehicle. Upon arriving at the site, the pilot performed a toe-in landing to discharge his crewmember. The crewmember proceeded to evaluate the vehicle while the pilot orbited the area. While orbiting, the pilot observed that low elevation clouds were approaching. However, the visibility initially was about 10 miles, and the cloud height appeared between 500 and 600 feet above the ground. After a few minutes, the crewmember returned to the helicopter, and they departed. Seconds after taking off the pilot lost visual reference with the ground. The pilot further indicated that he continued flying by reference to his flight instruments and the helicopter began spinning. Between 1 and 1.5 minutes later the spinning stopped, and the helicopter lost altitude until impacting the mountainside. ## Factual narrative On March 9, 1999, about 1755 hours Pacific standard time, a McDonnell Douglas 600N, N626SB, entered instrument meteorological conditions (IMC) and collided with 4,700-foot mean sea level mountainous terrain about 7 miles north of Rialto, California. A company visual flight rules (VFR) flight plan was filed. The helicopter was substantially damaged. The commercial pilot, the flight officer (crewmember), and the passenger sustained minor injuries. The aircraft was operated by the San Bernardino County Sheriff's Department, San Bernardino, California, as a public-use aircraft under the provisions of 14 CFR Part 91. The local area flight originated from San Bernardino about 1708. In the pilot's completed report, and during an interview, he indicated that the accident occurred while on a routine law enforcement patrol flight. In summary, the pilot reported that he was on a mission to investigate circumstances related to an apparent abandoned vehicle. Upon arriving at the mountainside, he performed a toe-in landing to discharge the crewmember. While the crewmember evaluated the vehicle, the pilot orbited the area, and noted that low elevation clouds were approaching. However, the visibility was about 10 miles, and the clouds appeared to have been between 500 and 600 feet above the ground. After a few minutes, the crewmember returned to the helicopter, and they departed. Seconds after taking off the pilot lost visual reference with the ground. The pilot further indicated that he continued flying by reference to his flight instruments and the helicopter began spinning. Between 1 and 1.5 minutes later the spinning stopped, and the helicopter lost altitude until impacting the mountainside. ## Aircraft - Registration: [N626SB](https://openairdocs.org/deregistered/N626SB-2005-08-04), registration cancelled 2005-08-04, S/N RN024, built 1997 (OpenAirDocs) - Reported make and model: McDonnell Douglas 600N - Registry model: [Mcdonnell Douglas Helicopter 600N](https://openairdocs.org/model/mcdonnell-douglas-helicopter-600n) (registry code 3027377) (OpenAirDocs) - Registry engine: [Allison 250-C47 series](https://openairdocs.org/engine/allison-250-c47-series) (registry code 03029, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: RN024 - Airframe hours: 266 - Engines: Allison 250-C47M 808 horsepower turbo shaft - Damage: Substantial damage - Flight: Public aircraft, Part 91 - Registered owner: San Bernardino Cty Sheriff Dpt - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, February 18, 1999, 66 hours before - Departed: L67, RIALTO, CA - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; commercial, military; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 1,654 total, 35 in this make and model, 1,612 as pilot in command, 104 in the last 90 days, 72 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Wind: 240° at 11 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 52 °F, dew point 43 °F - Altimeter: 30.00 inHg - Observed at: ONT, 17 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 19990309002109A](https://openairdocs.org/incident/19990309002109A), Mar 9, 1999: Doug 600N, Rialto, CA, Substantial damage. San bernadino county sheriff's department public use 1997 MD-600N helicopter crashed under unknown circumstances in the san bernadino mountains near lake… 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.