NTSB Factual Report

On April 21, 1994, at 2001 Pacific daylight time, a Continental Copters MK5A, N9061T, collided with power lines while engaged in night aerial application operations near Brawley, California. The helicopter was operated by Streeter Flying Service of Turlock, California, under 14 CFR Part 137. Visual meteorological conditions prevailed at the time and no flight plan was filed. The helicopter was destroyed in the collision sequence. The certificated commercial pilot, the sole occupant, sustained fatal injuries. The flight originated from a truck at the field to be sprayed on the day of the accident about 1930 hours.

A Federal Aviation Administration (FAA) inspector from the San Diego, California, Flight Standards District Office responded to the accident site, examined the wreckage, and interviewed the witnesses. His detailed report is attached to this document as an exhibit.

According to the inspector, there were no eyewitnesses to the power line collision. Two company loaders were waiting with the support truck next to the field being sprayed. They reported that the helicopter completed the application to the field and passed by their location in an easterly direction to make an approach and landing at the truck into the southwesterly prevailing wind. The loaders reported that as the helicopter passed their location, all of the exterior work lights were turned on. When the helicopter did not arrive at the truck after about 10 minutes time, they began a search and found the crashed helicopter in an alfalfa field about 1/2 mile east-northeast of the truck.

The witnesses reported that the weather conditions were clear and the wind was from the southwest at about 8 knots. A National Transportation Safety Board computer program was used to determine the positions of the sun and moon at the time of the accident. The sun was 8 degrees below the horizon. The moon was located 54 degrees above the horizon on a magnetic azimuth of 130 degrees. Eighty-one percent of the moon's disk was illuminated.

The FAA inspector reported that the field where the helicopter crashed is bordered on the southern end by a power line strung between wooden telephone-type poles. The power line is oriented in an east/west direction. Three 3/8-inch #4 ACSR conductor wires are strung on the pole tops and have an average above ground height of 25 feet.

One of the wires was found severed at a point 129 feet west of the second pole in an easterly direction from the field's western border. Color transfer matching the rotor blade paint was noted on the wire. One main rotor blade was observed to have impressions in the paint which corresponded to the size and pattern of the severed wire.

The FAA inspector found no evidence of a mechanical discrepancy during his examination of the wreckage. The military style cotton seatbelt and one shoulder harness strap were found to have failed. The Imperial County Coroner's deputy who removed the pilot's remains stated that the remaining shoulder harness strap was wrapped around the pilot's neck. The Coroner's Office performed an autopsy on the pilot and reported the cause of death as asphyxiation. No evidence of alcohol or drugs were found during the toxicological tests on samples taken from the pilot.

All of the helicopter historical records were reviewed by the FAA inspector and his report of the review is attached to this document. The Continental Copters MK5A helicopter is a rebuilt and converted U.S. Army OH-13H, manufactured under FAA Type Certificate H5SW. The accident helicopter was converted from a U.S. Army OH-13H to the Continental Copters MK5A configuration in 1975. The inspector stated that he found no record of the pilot restraint system installation or any repairs to the system.

NTSB Probable Cause

FAILURE OF THE PILOT TO MAINTAIN SUFFICIENT ALTITUDE, WHILE MANEUVERING TO LAND AFTER COMPLETING AERIAL APPLICATION. FACTORS RELATED TO THE ACCIDENT WERE: DARKNESS AND THE LACK OF VISUAL CUES FOR THE PILOT TO DETECT THE OBSTRUCTION (POWER LINE).