Bell 206 N57AW accident near Benson, Arizona

Probable cause

The pilot’s continued visual flight into instrument meteorological conditions which resulted in an inflight collision with terrain. Contributing to the accident was the pilot’s inadequate preflight planning, during which he failed to identify forecasted deteriorating weather conditions along the route of flight.

NTSB analysis

The helicopter was on a visual flight rules (VFR) repositioning flight in preparation for providing contracted air support capability to the local sheriff's office the next day. The operator reported that the helicopter did not arrive at the intended destination, and the wreckage was located 29 miles north of the intended destination. The helicopter was fragmented into multiple pieces along a 174-ft debris path. Ground scars and wreckage distribution were consistent with collision with terrain while in forward flight. The observations from a weather station located 3 miles east-southeast of the accident site indicated ceilings less than 500 ft and visibility less than 1 mile were likely at the time of the accident. The relative humidity had rapidly increased above 90 percent immediately before the accident, which would be indicative of cloud cover and mist at or near the surface. Witnesses living in the local area reported that the visibility at ground level was very limited, with low clouds and fog. Observations near the destination showed lowered visibility and low ceilings as the rain moved eastward through the accident area. Gusty winds ahead of the lowering ceilings would have likely created low-level wind shear. The operator's flight data monitoring system indicated that the helicopter was flying along an interstate about 300 ft above ground level (agl), which decreased to about 200 ft agl, likely as the visibility was reduced. However, the last recorded points indicated that the helicopter had climbed to about 500 ft agl, and was no longer tracking the interstate. It is likely that the VFR flight encountered instrument meteorological conditions, and the pilot was trying to maneuver to an area with greater visibility when the helicopter collided with terrain.

Weather information available to the pilot before takeoff showed a cold front between the departure airport and destination, with forecasted low clouds, rain, ceilings below 600 ft, and gusty winds associated with that front. It was the pilot's responsibility to review the weather before all Part 91 flights; the chief pilot was not required to review the conditions with the pilot for such flights. Had the pilot conducted thorough preflight planning, he should have identified the deteriorating weather conditions and recognized that he could not complete the VFR flight.

Text from the NTSB. Open the NTSB docket for WPR15FA072 for the full record.