On June 14, 1998, a Bell 47G-4A (registration N110DT) was involved in an aviation accident near Shafter, CA. Investigators recorded the probable cause as: The pilot's steep downwind approach, which resulted in settling with power (vortex ring state) at an altitude too low for recovery. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter crashed approximately 500 feet west of its intended landing pad after the pilot made a steep downwind approach, entering vortex ring state at low altitude. The main rotor severed the tail boom.
Incident Details
During a landing approach, the pilot conducted a steep downwind approach to the intended landing pad. While executing this maneuver, the helicopter entered a condition known as settling with power, or vortex ring state. The pilot reported that the altitude was insufficient to recover from this aerodynamic phenomenon. The helicopter subsequently impacted terrain approximately 500 feet west of the intended landing zone. Upon impact, the main rotor blades severed the tail boom.
Pilot's Statement
The pilot stated that no mechanical malfunctions were experienced with the helicopter prior to the accident. He further noted that a shallower approach would have been more appropriate for the conditions. The occurrence highlights the importance of maintaining adequate altitude margins when conducting approaches in settling with power conditions.
Probable cause
The pilot's steep downwind approach, which resulted in settling with power (vortex ring state) at an altitude too low for recovery.