Pilot Debrief

HUGHES 369 near Granger, TX — 2018-08-21

Final reportWPR18FA232
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Date
2018-08-21
Location
Granger, TX, USA
Airport
GTU
Aircraft
HUGHES 369
Registration
N530FU
Category
Helicopter
Highest injury
Fatal
Fatalities
2
Phase of flight
Maneuvering

Probable cause

The failure of both pilots to see and avoid a power line while maneuvering at low altitude. Contributing to the accident was the flight instructor's decision to not follow the training syllabus and allow the low-level high-speed flight.

Contributing factors

Contributing to the accident was the flight instructor's decision to not follow the training syllabus and allow the low-level high-speed flight.

NTSB narrative

The flight instructor was providing emergency procedure refresher training, as part of a contract between the US Army and a private contractor, to special operations pilots with the Jordanian Air Force. The accident was intended to be an introductory orientation flight for the pilot receiving instruction of the airports areas where the training would be occurring. Radar data indicated that the helicopter traveled east from the departure airport and climbed to an altitude of about 500 ft above ground level (agl). Afterward, the helicopter began to descend, and flew at altitudes that varied between 0 and 120 ft agl at a groundspeed of about 90 knots. A witness saw the helicopter rapidly approaching his location and reported that the helicopter was flying low in a nose-down attitude. A short time later, the helicopter struck and severed a steel wire power distribution line, and continued to fly until the helicopter impacted the ground about 950 ft beyond the impact point with the line. Most of the severed power line was continuous to the main wreckage location, having likely trailed or been attached to the helicopter after impact. According to the radar data, and impact trajectory, the 36-ft-tall power line support poles would have been hidden from the pilots' view by a stand of trees as the helicopter approached the area. Postaccident examination revealed no anomalies with the airframe or engine that would have precluded normal operation of the helicopter. The wreckage location, which was well beyond the impact point with the power line, was consistent with the helicopter operating at a high forward speed and likely a high engine power. The flight instructor was highly experienced in the accident helicopter make and model and had an extensive military career flying attack missions in helicopters. These missions included navigation and aerial gunnery, which would have required low-level flight close to terrain. Likewise, the pilot receiving instruction flew similar attack missions in helicopters with the Jordanian military. Therefore, it is likely that the flight instructor decided to intentionally deviate from the training syllabus and perform, or allow the pilot receiving instruction to perform, a high-speed, nap-of-the-earth flight for personal reasons, possibly to simulate their working environment, make the flight more interesting or engaging, push limits, or impress each other. The flight instructor had used the sedating antihistamine cetirizine at some time before the accident flight. Although the levels of the drug were well below the therapeutic range, it is not possible to determine if he could have been impaired by the sedating effects during the accident sequence.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Instructor could have prevented low-level flight maneuvers during training.

NTSB coding

Evidence available

  • ADS-B / radar
  • 10 docket documents
View NTSB final reportView NTSB docket

Docket documents10

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