Offering Aviation History & Adventure First-Hand!



Powerlines over Troubled Waters

The Crash of the Clean Bay Helicopter Charter

Near Crockett, California

January 11, 1992

The Rotary Wing Edge...

Sometimes, an aircraft is simply a means to expedite the execution of one's official responsibilities. Transportation to and from stations, duties such as surveying disaster sites, inspecting of underway vessels, and servicing unmanned aids to navigation, all involve the movement of Coast Guard personnel via the air, and yet minimize the use of their aviation assets that are better equipment to their specialty use as SAR platforms, drug interdiction aircraft, and the various other duties assigned to Coast Guard air stations throughout the United States.

To ease the workload, the Coast Guard will often coordinate, and sometimes contract out, aircraft for use on a short-term basis. Also, Coast Guardsmen are not beyond “hitching a ride” on an aircraft in the furtherance of their duties. After all, overlooking a situation from the air can add an extra dimension of understanding to a problem, or help determine the cause and potential effects on a grander scale.

And so, on Saturday, January 11th, 1992, Clean Bay, a private, nonprofit oil cleanup cooperative located in the San Francisco Bay area, chartered the helicopter from Air There Helicopters, to investigate an oil spill. The million-barrel capacity oil tanker “Overseas Boston” had dumped oil-contaminated waste water into the Carquinez Straits, the waterway connecting the Sacramento River Delta to San Pablo Bay, north of San Francisco Bay. By its third day, the spill was judged to be minor in size, but still a cause for concern, as Clean Bay had skimmed several barrels of oil off the waters' surface on the spill's first day.

Clean Bay was formed in 1971 by oil companies to react to oil spills from tankers or from the refineries along San Pablo and Suisun bays on the northern Contra Costa County shoreline. Clean Bay’s manager, Stephen Ricks, directed that a helicopter be hired to help locate the exact location of the oil to speed and focus skimming efforts.

Patrick Corr, at Helicopter Adventures in Concord, organized the helicopter flight for Clean Bay. But Corr determined that his company would be unable to accommodate Clean Bay's schedule and arranged for another helicopter operator, Air There - based at Gnoss Field in Marin County - to make the flight from their facility.

A Cabin of Experts...

The helicopter, a Bell 206B-III “Jet Ranger”, built in 1982 and registered as N95AT, carried four passengers - Gregory William Cook, 44, a employee of the Fish & Game department of California; Sonia Alexandra Linnik Hamilton, 35, also a Fish & Game employee; Robert Brooks Jean, 40, a consultant hired by Clean Bay and 31 year old Coast Guard Lieutenant Carl S. Johnson – the assistant supervisor of Marine Safety Detachment at Concord. Its pilot: Charles Patrick Walter - a native of Wisconsin and owner of Air There, was a veteran aviator with nearly 30 years flight experience.

Walter had distinguished himself several years prior on New Years' Eve, 1986, by rescuing stranded guests from the burning DuPont Plaza Hotel in Candado, Puerto Rico - the most catastrophic hotel fire in Puerto Rican history.

Cook and Hamilton were both recent additions to Fish & Game's Office of Oil Spill Prevention and Response – an office created in response to a 1990 oil spill off Huntington Beach in Southern California.

Taking off from Concord's Buchannan Field, the Jet Ranger flew low - in a slow cruise flight about 200 feet above ground level - along the hills of Contra Costa's shoreline towards San Pablo Bay. But, about twenty minutes later, as it approached the waters of the bay – on a route and in an area he was very familiar with - the pilot collided nearly perpendicular with a power line, which was depicted on the aeronautical chart, that spanned the Carquinez Strait.

Witnesses to Disaster...

Two fishermen – Ron Moniz, 41, and Richard Shoup, both of Benicia - told the Associated Press that they saw the low-flying helicopter and waved to the pilot just before it snagged the power lines. "As soon as he waved, he hit this cable and he pulled his arm back in and that was it. The thing just dropped. It was intact. The rotors were bent up, but there was no explosion," said Moniz.

The pair hurried to where the helicopter entered the water, about 50 yards from where they were fishing, near a huge waterfront sugar processing plant owned by the C & H Sugar Company, but the craft had sunk.

"The aircraft just dropped and sank within five seconds," Moniz said. The fishermen circled the area as other witnesses radioed authorities, but they recovered only a small piece of fiberglass. All 5 aboard were missing, and presumed to have gone down with the Jet Ranger. Three other pieces of the helicopter, including the rotor, were recovered several hours after the crash. But it would require divers to locate and recover the remains of the chopper and those aboard.


Wet-suited divers searching the wreckage, located in 60 feet of water, were hampered by stiff current, poor visibility and 40-degree water temperature. "It's very black, very dark, very cold. You just go by feel," said Sergeant John Humphrey, one of the divers for the Sheriff's department. 'It's just like walking in your house in the dark. You're obviously going to bump into things and you might as well close your eyes."

Three of the bodies were recovered in relatively short-order, but the bodies of Walter and Jean were pinned in the helo's wreckage.

"They located the body, but they don't know if they can remove it," said Shelly Freier, a Coast Guard spokeswoman. "The pilot is wedged in by debris and, with the visibility at zero down there, it will be hard to remove him."

Special equipment was brought in – including a special tracking device that was attached to Walter's body in case it separated from the wreckage and carried by the strong currents – to aid in extricating the remains. But in the end, the wreckage, along with Walter's body, was lifted to the water's surface the Thursday after the mishap.

As part of the investigation, an FAA inspector who flew the same route as the accident pilot reported that the power line was difficult to observe until he was within 1000 ft of it. The inspector indicated that the lack of conspicuity may be related to the fact that the towers from which the line had been suspended across the strait were located 4426 feet apart.

In August of 1993, the National Transportation Safety Board determined the probable cause of the accident was the pilot's failure to maintain vigilant watch for obstructions – in this case: the inconspicuous power line that was supported by distant towers - while intentionally cruising slowly at a low altitude.


The state of California was warned as far back as 1977 that power lines across the Carquinez Strait, snagged by helicopters in two fatal crashes, pose a danger and should be marked. However, a subsequent investigation conducted by lawyers representing the estates of Cook and Hamilton revealed that PG&E, the utility company responsible for the power lines since their construction in 1901, had abandoned the wires some years earlier. The wires thus no longer carried electrical current. California's Public Utilities Commission requires that electric companies dismantle their lines promptly after abandoning them. Had PG&E done so in this case, the accident would most likely never occurred.

PG&E countered on the grounds that, regulations aside, the pilot should have seen and avoided the wires - a correct assumption on the duties of a pilot inflight. According to PG&E, the towers from which the lines were hung was so large in size that the pilot could not have missed it had he been paying attention. Cook and Hamilton's lawyers commissioned a series of aerial photographs that showed that, from the pilot's point of view in the cockpit, the powerlines' towers disappeared into the superstructure of a nearby Carquinez Bridge. Without the towers to serve as a warning, the unmarked wires were virtually invisible.

Confronted with the evidence, PG&E settled the wrongful death claims of the two estates shortly before the trial before San Francisco County Superior Court in February of 1993.


As a result of this mishap, the California Association of Professional Scientists negotiated a special provision in the CAPS Memorandum of Understanding, Section 5.11, which provides a $50,000 air travel benefit to Department of Fish & Game scientists killed while flying during the course of their work – a direct result of Cook and Hamilton's untimely demise.

Owned by the Overseas Shipholding Group (OSG), the “Overseas Boston” would continue oil transport service, and be involved with several more oil spills – most notably in June of 2001. Overseas Shipholding, based in New York, sold the Overseas Boston for scrap for about $5.1 million in January of 2004. New laws, including a ban placed by the United Nations, curtailed the use of single-hull oil tankers worldwide. A new “Overseas Boston” was built and placed into service in 2009.

Also in 2004, Clean Bay merged with the Marine Spill Response Corporation.



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