Casualties unknown

1999-03-10: Mcdonnell Douglas 600N (N626SB) — Rialto, CA

Rialto, CA, US

On March 10, 1999, a Mcdonnell Douglas 600N (registration N626SB) was involved in an aviation accident near Rialto, CA. Investigators recorded the probable cause as: 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. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A law enforcement helicopter impacted a mountainside after the pilot lost visual reference with the ground while departing from a landing site. The pilot reported spinning and altitude loss before impact.

Overview

A helicopter conducting a law enforcement patrol flight struck a mountainside after the pilot lost visual reference with the ground shortly after takeoff. The incident occurred during a mission to investigate an apparent abandoned vehicle.

Sequence of Events

According to the pilot's account, the helicopter was on a routine patrol flight when the pilot responded to a location on a mountainside at 4,700 feet mean sea level to examine a suspected abandoned vehicle. Upon arrival, the pilot performed a toe-in landing to let a crewmember exit. The crewmember proceeded to evaluate the vehicle while the pilot orbited the area.

While orbiting, the pilot observed low elevation clouds approaching. However, visibility initially remained about 10 miles, and the cloud height appeared to be between 500 and 600 feet above ground level.

After a few minutes, the crewmember returned to the helicopter, and the flight departed. Seconds after takeoff, the pilot lost visual reference with the ground. The pilot indicated that he continued flying by reference to his flight instruments, but the helicopter began spinning. The spinning continued for between one and one-and-a-half minutes before it stopped. Following the cessation of the spin, the helicopter lost altitude until it impacted the mountainside.

Pilot's Account

The pilot reported that the loss of visual reference occurred abruptly after takeoff. He relied on flight instruments to maintain control, but the helicopter entered a spin. After the spin stopped, the helicopter descended and struck the terrain.

Investigation

No further details from the investigation have been released regarding the cause of the accident or the condition of the occupants or aircraft.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001205X00356. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.