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ASN Wikibase Occurrence # 236306
Last updated: 9 September 2021
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Time:23:47 LT
Type:Silhouette image of generic B06 model; specific model in this crash may look slightly different
Bell 206B-3 JetRanger III
Owner/operator:W T Byler Co Inc
Registration: N417WT
MSN: 4591
Fatalities:Fatalities: 3 / Occupants: 3
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:Chalk Bluff Park, Uvalde county, TX -   United States of America
Phase: En route
Departure airport:Private Ranch, TX
Destination airport:San Antonio, TX (SAT)
Investigating agency: NTSB
The pilot and two passengers onboard the turboshaft-powered helicopter departed from a private ranch on a night cross-country flight in visual meteorological conditions. Video evidence from witnesses who observed the departure showed that bright flood lights were shown directly at the helicopter during the departure. The helicopter impacted terrain shortly after takeoff about 100 ft below the top of a 1,500-ft hill and about 5 miles east of the departure point.

An automated weather station, located 13 miles southeast of the departure site, at 0015 recorded, clear skies, and an altimeter setting of 29.97 inHg. A review of weather information about the time of the accident revealed a small area of cloud ceilings east of the departure point. Based upon the helicopter's recorded route of flight, it is unlikely that the helicopter encountered this area of reduced visibility/ceilings.

Examination of the helicopter revealed no evidence of any mechanical malfunctions or anomalies that would have precluded normal operation. Data from the helicopter's flight displays revealed that the helicopter's altimeter was set at 30.05 inches of mercury (inHg); The altimeter setting at the station nearest the accident site was 29.97 inHg. This difference would have resulted in the helicopter's altimeter indicating a higher altitude than the helicopter's actual altitude. The display's data also indicated the helicopter's flight path towards its destination airport. The flight display's last indicated altitude was 1,538 ft, which would have only provided marginal obstacle clearance.

Additionally, the helicopter's terrain avoidance and warning system low altitude alerts were set to "inhibit", or turned off; therefore, the pilot would not have received a terrain warning message. Flight information from the displays did not record any evasive maneuvering, and it is likely that the pilot did not see the terrain before impact.

Autopsy and toxicology testing of the pilot did not reveal evidence of incapacitation. A review of the pilot's medical information indicated that he had been diagnosed with early cataracts; the pilot first reported cataracts to the FAA in 2005, and it is possible that they could have increased in severity enough to have compromised his night vision and contributed to his difficulty avoiding the hill. Additionally, the pilot's eyesight may not have adjusted to the night conditions after being exposed to bright lights during departure. However, the severity of his cataracts at the time of the accident is unknown, and whether visual limitations from cataracts or bright lights contributed to the accident, could not be determined.

The accident is consistent with control flight into terrain during dark night conditions

Probable Cause: The pilot's controlled flight into terrain during night visual meteorological conditions. Contributing to the accident was the pilot improper decision to inhibit the helicopter's terrain warning systems and flight at low altitude.



Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Duration: 1 year and 6 months
Download report: Final report


Revision history:

22-May-2020 09:26 ASN Update Bot Added
01-Nov-2020 15:02 Aerossurance Updated [Date, Time, Source, Narrative, Accident report]
01-Nov-2020 19:24 Aerossurance Updated [Source]
02-Nov-2020 12:24 Aerossurance Updated [Embed code]

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